diff --git a/patch.txt b/patch.txt
index 53f4212..b4f98e5 100644
--- a/patch.txt
+++ b/patch.txt
@@ -434,19 +434,27 @@
 
  func runBuild(cmd *base.Command, args []string) {
  	BuildInit()
-diff -u -r ./internal/work/buildid.go /Users/rsc/src/golang.org/x/vgo/vendor/cmd/go/internal/work/buildid.go
---- ./internal/work/buildid.go	2018-07-06 16:52:53.000000000 -0400
-+++ /Users/rsc/src/golang.org/x/vgo/vendor/cmd/go/internal/work/buildid.go	2018-06-27 21:01:27.000000000 -0400
-@@ -134,6 +134,8 @@
+diff -u -r ./internal/work/buildid.go /home/bcmills/src/golang.org/x/vgo/vendor/cmd/go/internal/work/buildid.go
+--- ./internal/work/buildid.go	2018-09-10 17:07:58.954625955 -0400
++++ /home/bcmills/src/golang.org/x/vgo/vendor/cmd/go/internal/work/buildid.go	2018-09-10 17:18:52.954844647 -0400
+@@ -18,7 +18,6 @@
+ 	"cmd/go/internal/load"
+ 	"cmd/go/internal/str"
+ 	"cmd/internal/buildid"
+-	"cmd/internal/objabi"
+ )
+ 
+ // Build IDs
+@@ -135,6 +134,8 @@
  	return string(dst[:])
  }
-
+ 
 +var oldVet = false
 +
  // toolID returns the unique ID to use for the current copy of the
  // named tool (asm, compile, cover, link).
  //
-@@ -166,6 +168,10 @@
+@@ -167,6 +168,10 @@
  // build setups agree on details like $GOROOT and file name paths, but at least the
  // tool IDs do not make it impossible.)
  func (b *Builder) toolID(name string) string {
@@ -457,7 +465,7 @@
  	b.id.Lock()
  	id := b.toolIDCache[name]
  	b.id.Unlock()
-@@ -190,6 +196,10 @@
+@@ -191,6 +196,10 @@
  	cmd.Stdout = &stdout
  	cmd.Stderr = &stderr
  	if err := cmd.Run(); err != nil {
@@ -467,6 +475,19 @@
 +		}
  		base.Fatalf("%s: %v\n%s%s", desc, err, stdout.Bytes(), stderr.Bytes())
  	}
+ 
+@@ -207,11 +216,6 @@
+ 		id = f[2]
+ 	}
+ 
+-	// For the compiler, add any experiments.
+-	if name == "compile" {
+-		id += " " + objabi.Expstring()
+-	}
+-
+ 	b.id.Lock()
+ 	b.toolIDCache[name] = id
+ 	b.id.Unlock()
 
 diff -u -r ./internal/work/exec.go /Users/rsc/src/golang.org/x/vgo/vendor/cmd/go/internal/work/exec.go
 --- ./internal/work/exec.go	2018-07-12 00:17:57.000000000 -0400
diff --git a/vendor/cmd/go/go_test.go b/vendor/cmd/go/go_test.go
index a0a29b9..8ce98c4 100644
--- a/vendor/cmd/go/go_test.go
+++ b/vendor/cmd/go/go_test.go
@@ -1295,6 +1295,7 @@
 	tg.grepStdout(`\* another-branch`, "not on correct default branch")
 }
 
+// Security issue. Don't disable. See golang.org/issue/22125.
 func TestAccidentalGitCheckout(t *testing.T) {
 	t.Skip("vgo") // Failing in main branch too: https://golang.org/issue/22983
 
@@ -1307,13 +1308,17 @@
 	defer tg.cleanup()
 	tg.parallel()
 	tg.tempDir("src")
+
 	tg.setenv("GOPATH", tg.path("."))
 
 	tg.runFail("get", "-u", "vcs-test.golang.org/go/test1-svn-git")
 	tg.grepStderr("src[\\\\/]vcs-test.* uses git, but parent .*src[\\\\/]vcs-test.* uses svn", "get did not fail for right reason")
 
-	tg.runFail("get", "-u", "vcs-test.golang.org/go/test2-svn-git/test2main")
-	tg.grepStderr("src[\\\\/]vcs-test.* uses git, but parent .*src[\\\\/]vcs-test.* uses svn", "get did not fail for right reason")
+	if _, err := os.Stat(tg.path("SrC")); err == nil {
+		// This case only triggers on a case-insensitive file system.
+		tg.runFail("get", "-u", "vcs-test.golang.org/go/test2-svn-git/test2main")
+		tg.grepStderr("src[\\\\/]vcs-test.* uses git, but parent .*src[\\\\/]vcs-test.* uses svn", "get did not fail for right reason")
+	}
 }
 
 func TestErrorMessageForSyntaxErrorInTestGoFileSaysFAIL(t *testing.T) {
@@ -3059,6 +3064,9 @@
 }
 
 func TestGoTestMainTwice(t *testing.T) {
+	if testing.Short() {
+		t.Skip("Skipping in short mode")
+	}
 	tg := testgo(t)
 	defer tg.cleanup()
 	tg.makeTempdir()
@@ -3542,24 +3550,43 @@
 }
 
 func TestGoGetInsecure(t *testing.T) {
-	testenv.MustHaveExternalNetwork(t)
+	test := func(t *testing.T, modules bool) {
+		testenv.MustHaveExternalNetwork(t)
 
-	tg := testgo(t)
-	defer tg.cleanup()
-	tg.makeTempdir()
-	tg.setenv("GOPATH", tg.path("."))
-	tg.failSSH()
+		tg := testgo(t)
+		defer tg.cleanup()
+		tg.makeTempdir()
+		tg.failSSH()
 
-	const repo = "insecure.go-get-issue-15410.appspot.com/pkg/p"
+		if modules {
+			tg.setenv("GOPATH", tg.path("gp"))
+			tg.tempFile("go.mod", "module m")
+			tg.cd(tg.path("."))
+			tg.setenv("GO111MODULE", "on")
+		} else {
+			tg.setenv("GOPATH", tg.path("."))
+			tg.setenv("GO111MODULE", "off")
+		}
 
-	// Try go get -d of HTTP-only repo (should fail).
-	tg.runFail("get", "-d", repo)
+		const repo = "insecure.go-get-issue-15410.appspot.com/pkg/p"
 
-	// Try again with -insecure (should succeed).
-	tg.run("get", "-d", "-insecure", repo)
+		// Try go get -d of HTTP-only repo (should fail).
+		tg.runFail("get", "-d", repo)
 
-	// Try updating without -insecure (should fail).
-	tg.runFail("get", "-d", "-u", "-f", repo)
+		// Try again with -insecure (should succeed).
+		tg.run("get", "-d", "-insecure", repo)
+
+		// Try updating without -insecure (should fail).
+		tg.runFail("get", "-d", "-u", "-f", repo)
+
+		if modules {
+			tg.run("list", "-m", "...")
+			tg.grepStdout("insecure.go-get-issue", "should find insecure module")
+		}
+	}
+
+	t.Run("gopath", func(t *testing.T) { test(t, false) })
+	t.Run("modules", func(t *testing.T) { test(t, true) })
 }
 
 func TestGoGetUpdateInsecure(t *testing.T) {
@@ -4202,9 +4229,10 @@
 	tg.setenv("GOPATH", tg.path("."))
 	const aPkgImportPath = "github.com/tmwh/go-get-issue-14450/a"
 	tg.run("get", aPkgImportPath)
-	tg.run("get", "-u", ".../")
-	tg.grepStderrNot("cannot find package", "did not update packages given wildcard path")
+	tg.runFail("get", "-u", ".../")
+	tg.grepStderr("cannot find package.*d-dependency/e", "should have detected e missing")
 
+	// Even though get -u failed, the source for others should be downloaded.
 	var expectedPkgPaths = []string{
 		"src/github.com/tmwh/go-get-issue-14450/b",
 		"src/github.com/tmwh/go-get-issue-14450-b-dependency/c",
@@ -5672,37 +5700,6 @@
 	tg.run("build", "-i", "-pkgdir=.", "runtime")
 }
 
-func TestGcflagsPatterns(t *testing.T) {
-	skipIfGccgo(t, "gccgo has no standard packages")
-	tg := testgo(t)
-	defer tg.cleanup()
-	tg.setenv("GOPATH", "")
-	tg.setenv("GOCACHE", "off")
-
-	tg.run("build", "-n", "-v", "-gcflags= \t\r\n -e", "fmt")
-	tg.grepStderr("^# fmt", "did not rebuild fmt")
-	tg.grepStderrNot("^# reflect", "incorrectly rebuilt reflect")
-
-	tg.run("build", "-n", "-v", "-gcflags=-e", "fmt", "reflect")
-	tg.grepStderr("^# fmt", "did not rebuild fmt")
-	tg.grepStderr("^# reflect", "did not rebuild reflect")
-	tg.grepStderrNot("^# runtime", "incorrectly rebuilt runtime")
-
-	tg.run("build", "-n", "-x", "-v", "-gcflags= \t\r\n reflect \t\r\n = \t\r\n -N", "fmt")
-	tg.grepStderr("^# fmt", "did not rebuild fmt")
-	tg.grepStderr("^# reflect", "did not rebuild reflect")
-	tg.grepStderr("compile.* -N .*-p reflect", "did not build reflect with -N flag")
-	tg.grepStderrNot("compile.* -N .*-p fmt", "incorrectly built fmt with -N flag")
-
-	tg.run("test", "-c", "-n", "-gcflags=-N", "-ldflags=-X=x.y=z", "strings")
-	tg.grepStderr("compile.* -N .*compare_test.go", "did not compile strings_test package with -N flag")
-	tg.grepStderr("link.* -X=x.y=z", "did not link strings.test binary with -X flag")
-
-	tg.run("test", "-c", "-n", "-gcflags=strings=-N", "-ldflags=strings=-X=x.y=z", "strings")
-	tg.grepStderr("compile.* -N .*compare_test.go", "did not compile strings_test package with -N flag")
-	tg.grepStderr("link.* -X=x.y=z", "did not link strings.test binary with -X flag")
-}
-
 func TestGoTestMinusN(t *testing.T) {
 	// Intent here is to verify that 'go test -n' works without crashing.
 	// This reuses flag_test.go, but really any test would do.
@@ -5849,57 +5846,6 @@
 	tg.run("test", "a")
 }
 
-// Issue 23150.
-func TestCpuprofileTwice(t *testing.T) {
-	tg := testgo(t)
-	defer tg.cleanup()
-	tg.parallel()
-	tg.tempFile("prof/src/x/x_test.go", `
-		package x_test
-		import (
-			"testing"
-			"time"
-		)
-		func TestSleep(t *testing.T) { time.Sleep(10 * time.Millisecond) }`)
-	tg.setenv("GOPATH", tg.path("prof"))
-	bin := tg.path("x.test")
-	out := tg.path("cpu.out")
-	tg.run("test", "-o="+bin, "-cpuprofile="+out, "x")
-	tg.must(os.Remove(out))
-	tg.run("test", "-o="+bin, "-cpuprofile="+out, "x")
-	tg.mustExist(out)
-}
-
-// Issue 23694.
-func TestAtomicCoverpkgAll(t *testing.T) {
-	tg := testgo(t)
-	defer tg.cleanup()
-	tg.parallel()
-
-	tg.tempFile("src/x/x.go", `package x; import _ "sync/atomic"; func F() {}`)
-	tg.tempFile("src/x/x_test.go", `package x; import "testing"; func TestF(t *testing.T) { F() }`)
-	tg.setenv("GOPATH", tg.path("."))
-	tg.run("test", "-coverpkg=all", "-covermode=atomic", "x")
-	if canRace {
-		tg.run("test", "-coverpkg=all", "-race", "x")
-	}
-}
-
-// Issue 23882.
-func TestCoverpkgAllRuntime(t *testing.T) {
-	tg := testgo(t)
-	defer tg.cleanup()
-	tg.parallel()
-
-	tg.tempFile("src/x/x.go", `package x; import _ "runtime"; func F() {}`)
-	tg.tempFile("src/x/x_test.go", `package x; import "testing"; func TestF(t *testing.T) { F() }`)
-	tg.setenv("GOPATH", tg.path("."))
-	tg.run("test", "-coverpkg=all", "x")
-	if canRace {
-		tg.run("test", "-coverpkg=all", "-race", "x")
-	}
-}
-
 func TestBadCommandLines(t *testing.T) {
 	tg := testgo(t)
 	defer tg.cleanup()
diff --git a/vendor/cmd/go/internal/cfg/zdefaultcc.go b/vendor/cmd/go/internal/cfg/zdefaultcc.go
index 7297f75..3f222d7 100644
--- a/vendor/cmd/go/internal/cfg/zdefaultcc.go
+++ b/vendor/cmd/go/internal/cfg/zdefaultcc.go
@@ -7,10 +7,10 @@
 func DefaultCC(goos, goarch string) string {
 	switch goos + `/` + goarch {
 	}
-	return "clang"
+	return "gcc"
 }
 func DefaultCXX(goos, goarch string) string {
 	switch goos + `/` + goarch {
 	}
-	return "clang++"
+	return "c++"
 }
diff --git a/vendor/cmd/go/internal/fmtcmd/fmt.go b/vendor/cmd/go/internal/fmtcmd/fmt.go
index 0e5509e..8e4ef37 100644
--- a/vendor/cmd/go/internal/fmtcmd/fmt.go
+++ b/vendor/cmd/go/internal/fmtcmd/fmt.go
@@ -60,7 +60,7 @@
 		}()
 	}
 	for _, pkg := range load.PackagesAndErrors(args) {
-		if modload.Enabled() && !pkg.Module.Main {
+		if modload.Enabled() && pkg.Module != nil && !pkg.Module.Main {
 			if !printed {
 				fmt.Fprintf(os.Stderr, "go: not formatting packages in dependency modules\n")
 				printed = true
diff --git a/vendor/cmd/go/internal/get/get.go b/vendor/cmd/go/internal/get/get.go
index fd97c6d..e4148bc 100644
--- a/vendor/cmd/go/internal/get/get.go
+++ b/vendor/cmd/go/internal/get/get.go
@@ -163,9 +163,8 @@
 	if *getT {
 		mode |= load.GetTestDeps
 	}
-	args = downloadPaths(args)
-	for _, arg := range args {
-		download(arg, nil, &stk, mode)
+	for _, pkg := range downloadPaths(args) {
+		download(pkg, nil, &stk, mode)
 	}
 	base.ExitIfErrors()
 
@@ -184,8 +183,7 @@
 	// This leads to duplicated loads of the standard packages.
 	load.ClearCmdCache()
 
-	args = load.ImportPaths(args)
-	load.PackagesForBuild(args)
+	pkgs := load.PackagesForBuild(args)
 
 	// Phase 3. Install.
 	if *getD {
@@ -195,7 +193,7 @@
 		return
 	}
 
-	work.InstallPackages(args)
+	work.InstallPackages(args, pkgs)
 }
 
 // downloadPaths prepares the list of paths to pass to download.
@@ -203,34 +201,21 @@
 // for a particular pattern, downloadPaths leaves it in the result list,
 // in the hope that we can figure out the repository from the
 // initial ...-free prefix.
-func downloadPaths(args []string) []string {
-	for _, arg := range args {
+func downloadPaths(patterns []string) []string {
+	for _, arg := range patterns {
 		if strings.Contains(arg, "@") {
 			base.Fatalf("go: cannot use path@version syntax in GOPATH mode")
 		}
 	}
-
-	args = load.ImportPathsForGoGet(args)
-	var out []string
-	for _, a := range args {
-		if strings.Contains(a, "...") {
-			var expand []string
-			// Use matchPackagesInFS to avoid printing
-			// warnings. They will be printed by the
-			// eventual call to importPaths instead.
-			if build.IsLocalImport(a) {
-				expand = search.MatchPackagesInFS(a)
-			} else {
-				expand = search.MatchPackages(a)
-			}
-			if len(expand) > 0 {
-				out = append(out, expand...)
-				continue
-			}
+	var pkgs []string
+	for _, m := range search.ImportPathsQuiet(patterns) {
+		if len(m.Pkgs) == 0 && strings.Contains(m.Pattern, "...") {
+			pkgs = append(pkgs, m.Pattern)
+		} else {
+			pkgs = append(pkgs, m.Pkgs...)
 		}
-		out = append(out, a)
 	}
-	return out
+	return pkgs
 }
 
 // downloadCache records the import paths we have already
@@ -255,7 +240,7 @@
 	}
 	load1 := func(path string, mode int) *load.Package {
 		if parent == nil {
-			return load.LoadPackage(path, stk)
+			return load.LoadPackageNoFlags(path, stk)
 		}
 		return load.LoadImport(path, parent.Dir, parent, stk, nil, mode|load.ResolveModule)
 	}
@@ -311,9 +296,9 @@
 		// for p has been replaced in the package cache.
 		if wildcardOkay && strings.Contains(arg, "...") {
 			if build.IsLocalImport(arg) {
-				args = search.MatchPackagesInFS(arg)
+				args = search.MatchPackagesInFS(arg).Pkgs
 			} else {
-				args = search.MatchPackages(arg)
+				args = search.MatchPackages(arg).Pkgs
 			}
 			isWildcard = true
 		}
@@ -344,7 +329,7 @@
 			base.Run(cfg.BuildToolexec, str.StringList(base.Tool("fix"), files))
 
 			// The imports might have changed, so reload again.
-			p = load.ReloadPackage(arg, stk)
+			p = load.ReloadPackageNoFlags(arg, stk)
 			if p.Error != nil {
 				base.Errorf("%s", p.Error)
 				return
diff --git a/vendor/cmd/go/internal/get/vcs.go b/vendor/cmd/go/internal/get/vcs.go
index a4fd28e..5cd164f 100644
--- a/vendor/cmd/go/internal/get/vcs.go
+++ b/vendor/cmd/go/internal/get/vcs.go
@@ -5,7 +5,6 @@
 package get
 
 import (
-	"bytes"
 	"encoding/json"
 	"errors"
 	"fmt"
@@ -428,19 +427,18 @@
 		fmt.Printf("cd %s\n", dir)
 		fmt.Printf("%s %s\n", v.cmd, strings.Join(args, " "))
 	}
-	var buf bytes.Buffer
-	cmd.Stdout = &buf
-	cmd.Stderr = &buf
-	err = cmd.Run()
-	out := buf.Bytes()
+	out, err := cmd.Output()
 	if err != nil {
 		if verbose || cfg.BuildV {
 			fmt.Fprintf(os.Stderr, "# cd %s; %s %s\n", dir, v.cmd, strings.Join(args, " "))
-			os.Stderr.Write(out)
+			if ee, ok := err.(*exec.ExitError); ok && len(ee.Stderr) > 0 {
+				os.Stderr.Write(ee.Stderr)
+			} else {
+				fmt.Fprintf(os.Stderr, err.Error())
+			}
 		}
-		return out, err
 	}
-	return out, nil
+	return out, err
 }
 
 // ping pings to determine scheme to use.
diff --git a/vendor/cmd/go/internal/imports/scan.go b/vendor/cmd/go/internal/imports/scan.go
index 095bb64..d944e95 100644
--- a/vendor/cmd/go/internal/imports/scan.go
+++ b/vendor/cmd/go/internal/imports/scan.go
@@ -37,6 +37,7 @@
 	imports := make(map[string]bool)
 	testImports := make(map[string]bool)
 	numFiles := 0
+Files:
 	for _, name := range files {
 		r, err := os.Open(name)
 		if err != nil {
@@ -48,6 +49,19 @@
 		if err != nil {
 			return nil, nil, fmt.Errorf("reading %s: %v", name, err)
 		}
+
+		// import "C" is implicit requirement of cgo tag.
+		// When listing files on the command line (explicitFiles=true)
+		// we do not apply build tag filtering but we still do apply
+		// cgo filtering, so no explicitFiles check here.
+		// Why? Because we always have, and it's not worth breaking
+		// that behavior now.
+		for _, path := range list {
+			if path == `"C"` && !tags["cgo"] && !tags["*"] {
+				continue Files
+			}
+		}
+
 		if !explicitFiles && !ShouldBuild(data, tags) {
 			continue
 		}
diff --git a/vendor/cmd/go/internal/list/list.go b/vendor/cmd/go/internal/list/list.go
index 7809163..f3cb4e4 100644
--- a/vendor/cmd/go/internal/list/list.go
+++ b/vendor/cmd/go/internal/list/list.go
@@ -20,6 +20,7 @@
 	"cmd/go/internal/cfg"
 	"cmd/go/internal/load"
 	"cmd/go/internal/modload"
+	"cmd/go/internal/str"
 	"cmd/go/internal/work"
 )
 
@@ -46,24 +47,25 @@
 to -f '{{.ImportPath}}'. The struct being passed to the template is:
 
     type Package struct {
-        Dir           string  // directory containing package sources
-        ImportPath    string  // import path of package in dir
-        ImportComment string  // path in import comment on package statement
-        Name          string  // package name
-        Doc           string  // package documentation string
-        Target        string  // install path
-        Shlib         string  // the shared library that contains this package (only set when -linkshared)
-        Goroot        bool    // is this package in the Go root?
-        Standard      bool    // is this package part of the standard Go library?
-        Stale         bool    // would 'go install' do anything for this package?
-        StaleReason   string  // explanation for Stale==true
-        Root          string  // Go root or Go path dir containing this package
-        ConflictDir   string  // this directory shadows Dir in $GOPATH
-        BinaryOnly    bool    // binary-only package: cannot be recompiled from sources
-        ForTest       string  // package is only for use in named test
-        DepOnly       bool    // package is only a dependency, not explicitly listed
-        Export        string  // file containing export data (when using -export)
-        Module        *Module // info about package's containing module, if any (can be nil)
+        Dir           string   // directory containing package sources
+        ImportPath    string   // import path of package in dir
+        ImportComment string   // path in import comment on package statement
+        Name          string   // package name
+        Doc           string   // package documentation string
+        Target        string   // install path
+        Shlib         string   // the shared library that contains this package (only set when -linkshared)
+        Goroot        bool     // is this package in the Go root?
+        Standard      bool     // is this package part of the standard Go library?
+        Stale         bool     // would 'go install' do anything for this package?
+        StaleReason   string   // explanation for Stale==true
+        Root          string   // Go root or Go path dir containing this package
+        ConflictDir   string   // this directory shadows Dir in $GOPATH
+        BinaryOnly    bool     // binary-only package: cannot be recompiled from sources
+        ForTest       string   // package is only for use in named test
+        Export        string   // file containing export data (when using -export)
+        Module        *Module  // info about package's containing module, if any (can be nil)
+        Match         []string // command-line patterns matching this package
+        DepOnly       bool     // package is only a dependency, not explicitly listed
 
         // Source files
         GoFiles         []string // .go source files (excluding CgoFiles, TestGoFiles, XTestGoFiles)
@@ -107,7 +109,7 @@
 path to the vendor directory (for example, "d/vendor/p" instead of "p"),
 so that the ImportPath uniquely identifies a given copy of a package.
 The Imports, Deps, TestImports, and XTestImports lists also contain these
-expanded imports paths. See golang.org/s/go15vendor for more about vendoring.
+expanded import paths. See golang.org/s/go15vendor for more about vendoring.
 
 The error information, if any, is
 
@@ -146,7 +148,8 @@
 The -compiled flag causes list to set CompiledGoFiles to the Go source
 files presented to the compiler. Typically this means that it repeats
 the files listed in GoFiles and then also adds the Go code generated
-by processing CgoFiles and SwigFiles.
+by processing CgoFiles and SwigFiles. The Imports list contains the
+union of all imports from both GoFiles and CompiledGoFiles.
 
 The -deps flag causes list to iterate over not just the named packages
 but also all their dependencies. It visits them in a depth-first post-order
@@ -266,7 +269,7 @@
 module paths match the pattern.
 A query of the form path@version specifies the result of that query,
 which is not limited to active modules.
-See 'go help module' for more about module queries.
+See 'go help modules' for more about module queries.
 
 The template function "module" takes a single string argument
 that must be a module path or query and returns the specified
@@ -303,6 +306,7 @@
 var nl = []byte{'\n'}
 
 func runList(cmd *base.Command, args []string) {
+	modload.LoadTests = *listTest
 	work.BuildInit()
 	out := newTrackingWriter(os.Stdout)
 	defer out.w.Flush()
@@ -506,7 +510,9 @@
 		a := &work.Action{}
 		// TODO: Use pkgsFilter?
 		for _, p := range pkgs {
-			a.Deps = append(a.Deps, b.AutoAction(work.ModeInstall, work.ModeInstall, p))
+			if len(p.GoFiles)+len(p.CgoFiles) > 0 {
+				a.Deps = append(a.Deps, b.AutoAction(work.ModeInstall, work.ModeInstall, p))
+			}
 		}
 		b.Do(a)
 	}
@@ -516,6 +522,10 @@
 		p.TestImports = p.Resolve(p.TestImports)
 		p.XTestImports = p.Resolve(p.XTestImports)
 		p.DepOnly = !cmdline[p]
+
+		if *listCompiled {
+			p.Imports = str.StringList(p.Imports, p.Internal.CompiledImports)
+		}
 	}
 
 	if *listTest {
diff --git a/vendor/cmd/go/internal/load/flag.go b/vendor/cmd/go/internal/load/flag.go
index d9177b0..7534e65 100644
--- a/vendor/cmd/go/internal/load/flag.go
+++ b/vendor/cmd/go/internal/load/flag.go
@@ -6,7 +6,6 @@
 
 import (
 	"cmd/go/internal/base"
-	"cmd/go/internal/search"
 	"cmd/go/internal/str"
 	"fmt"
 	"strings"
@@ -92,52 +91,3 @@
 	}
 	return flags
 }
-
-var (
-	cmdlineMatchers        []func(*Package) bool
-	cmdlineMatcherLiterals []func(*Package) bool
-)
-
-// SetCmdlinePatterns records the set of patterns given on the command line,
-// for use by the PerPackageFlags.
-func SetCmdlinePatterns(args []string) {
-	setCmdlinePatterns(args, base.Cwd)
-}
-
-func setCmdlinePatterns(args []string, cwd string) {
-	if len(args) == 0 {
-		args = []string{"."}
-	}
-	cmdlineMatchers = nil // allow reset for testing
-	cmdlineMatcherLiterals = nil
-	for _, arg := range args {
-		cmdlineMatchers = append(cmdlineMatchers, MatchPackage(arg, cwd))
-	}
-	for _, arg := range args {
-		if !strings.Contains(arg, "...") && !search.IsMetaPackage(arg) {
-			cmdlineMatcherLiterals = append(cmdlineMatcherLiterals, MatchPackage(arg, cwd))
-		}
-	}
-}
-
-// isCmdlinePkg reports whether p is a package listed on the command line.
-func isCmdlinePkg(p *Package) bool {
-	for _, m := range cmdlineMatchers {
-		if m(p) {
-			return true
-		}
-	}
-	return false
-}
-
-// isCmdlinePkgLiteral reports whether p is a package listed as
-// a literal package argument on the command line
-// (as opposed to being the result of expanding a wildcard).
-func isCmdlinePkgLiteral(p *Package) bool {
-	for _, m := range cmdlineMatcherLiterals {
-		if m(p) {
-			return true
-		}
-	}
-	return false
-}
diff --git a/vendor/cmd/go/internal/load/pkg.go b/vendor/cmd/go/internal/load/pkg.go
index f27fdc1..ec2fa73 100644
--- a/vendor/cmd/go/internal/load/pkg.go
+++ b/vendor/cmd/go/internal/load/pkg.go
@@ -32,13 +32,14 @@
 	ModInit func()
 
 	// module hooks; nil if module use is disabled
-	ModBinDir            func() string                                                   // return effective bin directory
-	ModLookup            func(parentPath, path string) (dir, realPath string, err error) // lookup effective meaning of import
-	ModPackageModuleInfo func(path string) *modinfo.ModulePublic                         // return module info for Package struct
-	ModImportPaths       func(args []string) []string                                    // expand import paths
-	ModPackageBuildInfo  func(main string, deps []string) string                         // return module info to embed in binary
-	ModInfoProg          func(info string) []byte                                        // wrap module info in .go code for binary
-	ModImportFromFiles   func([]string)                                                  // update go.mod to add modules for imports in these files
+	ModBinDir            func() string                                       // return effective bin directory
+	ModLookup            func(path string) (dir, realPath string, err error) // lookup effective meaning of import
+	ModPackageModuleInfo func(path string) *modinfo.ModulePublic             // return module info for Package struct
+	ModImportPaths       func(args []string) []*search.Match                 // expand import paths
+	ModPackageBuildInfo  func(main string, deps []string) string             // return module info to embed in binary
+	ModInfoProg          func(info string) []byte                            // wrap module info in .go code for binary
+	ModImportFromFiles   func([]string)                                      // update go.mod to add modules for imports in these files
+	ModDirImportPath     func(string) string                                 // return effective import path for directory
 )
 
 var IgnoreImports bool // control whether we ignore imports in packages
@@ -60,15 +61,17 @@
 	Doc           string                `json:",omitempty"` // package documentation string
 	Target        string                `json:",omitempty"` // installed target for this package (may be executable)
 	Shlib         string                `json:",omitempty"` // the shared library that contains this package (only set when -linkshared)
-	Goroot        bool                  `json:",omitempty"` // is this package found in the Go root?
-	Standard      bool                  `json:",omitempty"` // is this package part of the standard Go library?
 	Root          string                `json:",omitempty"` // Go root or Go path dir containing this package
 	ConflictDir   string                `json:",omitempty"` // Dir is hidden by this other directory
-	BinaryOnly    bool                  `json:",omitempty"` // package cannot be recompiled
 	ForTest       string                `json:",omitempty"` // package is only for use in named test
-	DepOnly       bool                  `json:",omitempty"` // package is only as a dependency, not explicitly listed
 	Export        string                `json:",omitempty"` // file containing export data (set by go list -export)
 	Module        *modinfo.ModulePublic `json:",omitempty"` // info about package's module, if any
+	Match         []string              `json:",omitempty"` // command-line patterns matching this package
+	Goroot        bool                  `json:",omitempty"` // is this package found in the Go root?
+	Standard      bool                  `json:",omitempty"` // is this package part of the standard Go library?
+	DepOnly       bool                  `json:",omitempty"` // package is only as a dependency, not explicitly listed
+	BinaryOnly    bool                  `json:",omitempty"` // package cannot be recompiled
+	Incomplete    bool                  `json:",omitempty"` // was there an error loading this package or dependencies?
 
 	// Stale and StaleReason remain here *only* for the list command.
 	// They are only initialized in preparation for list execution.
@@ -107,7 +110,7 @@
 	Deps      []string          `json:",omitempty"` // all (recursively) imported dependencies
 
 	// Error information
-	Incomplete bool            `json:",omitempty"` // was there an error loading this package or dependencies?
+	// Incomplete is above, packed into the other bools
 	Error      *PackageError   `json:",omitempty"` // error loading this package (not dependencies)
 	DepsErrors []*PackageError `json:",omitempty"` // errors loading dependencies
 
@@ -157,6 +160,7 @@
 	// Unexported fields are not part of the public API.
 	Build             *build.Package
 	Imports           []*Package           // this package's direct imports
+	CompiledImports   []string             // additional Imports necessary when using CompiledGoFiles (all from standard library)
 	RawImports        []string             // this package's original imports as they appear in the text of the program
 	ForceLibrary      bool                 // this package is a library (even if named "main")
 	CmdlineFiles      bool                 // package built from files listed on command line
@@ -319,7 +323,8 @@
 }
 
 // An ImportStack is a stack of import paths, possibly with the suffix " (test)" appended.
-// TODO(bcmills): When the tree opens for 1.12, replace the suffixed string with a struct.
+// The import path of a test package is the import path of the corresponding
+// non-test package with the suffix "_test" added.
 type ImportStack []string
 
 func (s *ImportStack) Push(p string) {
@@ -372,15 +377,17 @@
 	}
 }
 
-// reloadPackage is like loadPackage but makes sure
+// ReloadPackageNoFlags is like LoadPackageNoFlags but makes sure
 // not to use the package cache.
-func ReloadPackage(arg string, stk *ImportStack) *Package {
+// It is only for use by GOPATH-based "go get".
+// TODO(rsc): When GOPATH-based "go get" is removed, delete this function.
+func ReloadPackageNoFlags(arg string, stk *ImportStack) *Package {
 	p := packageCache[arg]
 	if p != nil {
 		delete(packageCache, p.Dir)
 		delete(packageCache, p.ImportPath)
 	}
-	return LoadPackage(arg, stk)
+	return LoadPackageNoFlags(arg, stk)
 }
 
 // dirToImportPath returns the pseudo-import path we use for a package
@@ -429,6 +436,9 @@
 // but possibly a local import path (an absolute file system path or one beginning
 // with ./ or ../). A local relative path is interpreted relative to srcDir.
 // It returns a *Package describing the package found in that directory.
+// LoadImport does not set tool flags and should only be used by
+// this package, as part of a bigger load operation, and by GOPATH-based "go get".
+// TODO(rsc): When GOPATH-based "go get" is removed, unexport this function.
 func LoadImport(path, srcDir string, parent *Package, stk *ImportStack, importPos []token.Position, mode int) *Package {
 	stk.Push(path)
 	defer stk.Pop()
@@ -468,6 +478,11 @@
 		}
 	}
 
+	parentPath := ""
+	if parent != nil {
+		parentPath = parent.ImportPath
+	}
+
 	// Determine canonical identifier for this package.
 	// For a local import the identifier is the pseudo-import path
 	// we create from the full directory to the package.
@@ -481,12 +496,8 @@
 	if isLocal {
 		importPath = dirToImportPath(filepath.Join(srcDir, path))
 	} else if cfg.ModulesEnabled {
-		parentPath := ""
-		if parent != nil {
-			parentPath = parent.ImportPath
-		}
 		var p string
-		modDir, p, modErr = ModLookup(parentPath, path)
+		modDir, p, modErr = ModLookup(path)
 		if modErr == nil {
 			importPath = p
 		}
@@ -557,11 +568,11 @@
 	}
 
 	// Checked on every import because the rules depend on the code doing the importing.
-	if perr := disallowInternal(srcDir, p, stk); perr != p {
+	if perr := disallowInternal(srcDir, parent, parentPath, p, stk); perr != p {
 		return setErrorPos(perr, importPos)
 	}
 	if mode&ResolveImport != 0 {
-		if perr := disallowVendor(srcDir, origPath, p, stk); perr != p {
+		if perr := disallowVendor(srcDir, parent, parentPath, origPath, p, stk); perr != p {
 			return setErrorPos(perr, importPos)
 		}
 	}
@@ -626,11 +637,7 @@
 // Go 1.11 module legacy conversion (golang.org/issue/25069).
 func ResolveImportPath(parent *Package, path string) (found string) {
 	if cfg.ModulesEnabled {
-		parentPath := ""
-		if parent != nil {
-			parentPath = parent.ImportPath
-		}
-		if _, p, e := ModLookup(parentPath, path); e == nil {
+		if _, p, e := ModLookup(path); e == nil {
 			return p
 		}
 		return path
@@ -922,10 +929,11 @@
 	return p
 }
 
-// disallowInternal checks that srcDir is allowed to import p.
+// disallowInternal checks that srcDir (containing package importerPath, if non-empty)
+// is allowed to import p.
 // If the import is allowed, disallowInternal returns the original package p.
 // If not, it returns a new package containing just an appropriate error.
-func disallowInternal(srcDir string, p *Package, stk *ImportStack) *Package {
+func disallowInternal(srcDir string, importer *Package, importerPath string, p *Package, stk *ImportStack) *Package {
 	// golang.org/s/go14internal:
 	// An import of a path containing the element “internal”
 	// is disallowed if the importing code is outside the tree
@@ -969,7 +977,6 @@
 		i-- // rewind over slash in ".../internal"
 	}
 
-	var where string
 	if p.Module == nil {
 		parent := p.Dir[:i+len(p.Dir)-len(p.ImportPath)]
 
@@ -984,21 +991,25 @@
 			return p
 		}
 	} else {
-		// p is in a module, so make it available based on the import path instead
+		// p is in a module, so make it available based on the importer's import path instead
 		// of the file path (https://golang.org/issue/23970).
-		parent := p.ImportPath[:i]
-		importer := strings.TrimSuffix((*stk)[len(*stk)-2], " (test)")
-		if str.HasPathPrefix(importer, parent) {
+		if importerPath == "." {
+			// The importer is a list of command-line files.
+			// Pretend that the import path is the import path of the
+			// directory containing them.
+			importerPath = ModDirImportPath(importer.Dir)
+		}
+		parentOfInternal := p.ImportPath[:i]
+		if str.HasPathPrefix(importerPath, parentOfInternal) {
 			return p
 		}
-		where = " in " + importer
 	}
 
 	// Internal is present, and srcDir is outside parent's tree. Not allowed.
 	perr := *p
 	perr.Error = &PackageError{
 		ImportStack: stk.Copy(),
-		Err:         "use of internal package " + p.ImportPath + " not allowed" + where,
+		Err:         "use of internal package " + p.ImportPath + " not allowed",
 	}
 	perr.Incomplete = true
 	return &perr
@@ -1023,10 +1034,11 @@
 	return 0, false
 }
 
-// disallowVendor checks that srcDir is allowed to import p as path.
+// disallowVendor checks that srcDir (containing package importerPath, if non-empty)
+// is allowed to import p as path.
 // If the import is allowed, disallowVendor returns the original package p.
 // If not, it returns a new package containing just an appropriate error.
-func disallowVendor(srcDir, path string, p *Package, stk *ImportStack) *Package {
+func disallowVendor(srcDir string, importer *Package, importerPath, path string, p *Package, stk *ImportStack) *Package {
 	// The stack includes p.ImportPath.
 	// If that's the only thing on the stack, we started
 	// with a name given on the command line, not an
@@ -1035,27 +1047,18 @@
 		return p
 	}
 
-	if p.Standard && ModPackageModuleInfo != nil {
-		// Modules must not import vendor packages in the standard library,
-		// but the usual vendor visibility check will not catch them
-		// because the module loader presents them with an ImportPath starting
-		// with "golang_org/" instead of "vendor/".
-		importer := strings.TrimSuffix((*stk)[len(*stk)-2], " (test)")
-		if mod := ModPackageModuleInfo(importer); mod != nil {
-			dir := p.Dir
-			if relDir, err := filepath.Rel(p.Root, p.Dir); err == nil {
-				dir = relDir
-			}
-			if _, ok := FindVendor(filepath.ToSlash(dir)); ok {
-				perr := *p
-				perr.Error = &PackageError{
-					ImportStack: stk.Copy(),
-					Err:         "use of vendored package " + path + " not allowed",
-				}
-				perr.Incomplete = true
-				return &perr
-			}
+	// Modules must not import vendor packages in the standard library,
+	// but the usual vendor visibility check will not catch them
+	// because the module loader presents them with an ImportPath starting
+	// with "golang_org/" instead of "vendor/".
+	if p.Standard && !importer.Standard && strings.HasPrefix(p.ImportPath, "golang_org") {
+		perr := *p
+		perr.Error = &PackageError{
+			ImportStack: stk.Copy(),
+			Err:         "use of vendored package " + path + " not allowed",
 		}
+		perr.Incomplete = true
+		return &perr
 	}
 
 	if perr := disallowVendorVisibility(srcDir, p, stk); perr != p {
@@ -1188,27 +1191,6 @@
 func (p *Package) load(stk *ImportStack, bp *build.Package, err error) {
 	p.copyBuild(bp)
 
-	// Decide whether p was listed on the command line.
-	// Given that load is called while processing the command line,
-	// you might think we could simply pass a flag down into load
-	// saying whether we are loading something named on the command
-	// line or something to satisfy an import. But the first load of a
-	// package named on the command line may be as a dependency
-	// of an earlier package named on the command line, not when we
-	// get to that package during command line processing.
-	// For example "go test fmt reflect" will load reflect as a dependency
-	// of fmt before it attempts to load as a command-line argument.
-	// Because loads are cached, the later load will be a no-op,
-	// so it is important that the first load can fill in CmdlinePkg correctly.
-	// Hence the call to a separate matching check here.
-	p.Internal.CmdlinePkg = isCmdlinePkg(p)
-	p.Internal.CmdlinePkgLiteral = isCmdlinePkgLiteral(p)
-
-	p.Internal.Asmflags = BuildAsmflags.For(p)
-	p.Internal.Gcflags = BuildGcflags.For(p)
-	p.Internal.Ldflags = BuildLdflags.For(p)
-	p.Internal.Gccgoflags = BuildGccgoflags.For(p)
-
 	// The localPrefix is the path we interpret ./ imports relative to.
 	// Synthesized main packages sometimes override this.
 	if p.Internal.Local {
@@ -1245,6 +1227,37 @@
 			return
 		}
 		_, elem := filepath.Split(p.Dir)
+		if cfg.ModulesEnabled {
+			// NOTE(rsc): Using p.ImportPath instead of p.Dir
+			// makes sure we install a package in the root of a
+			// cached module directory as that package name
+			// not name@v1.2.3.
+			// Using p.ImportPath instead of p.Dir
+			// is probably correct all the time,
+			// even for non-module-enabled code,
+			// but I'm not brave enough to change the
+			// non-module behavior this late in the
+			// release cycle. Maybe for Go 1.12.
+			// See golang.org/issue/26869.
+			_, elem = pathpkg.Split(p.ImportPath)
+
+			// If this is example.com/mycmd/v2, it's more useful to install it as mycmd than as v2.
+			// See golang.org/issue/24667.
+			isVersion := func(v string) bool {
+				if len(v) < 2 || v[0] != 'v' || v[1] < '1' || '9' < v[1] {
+					return false
+				}
+				for i := 2; i < len(v); i++ {
+					if c := v[i]; c < '0' || '9' < c {
+						return false
+					}
+				}
+				return true
+			}
+			if isVersion(elem) {
+				_, elem = pathpkg.Split(pathpkg.Dir(p.ImportPath))
+			}
+		}
 		full := cfg.BuildContext.GOOS + "_" + cfg.BuildContext.GOARCH + "/" + elem
 		if cfg.BuildContext.GOOS != base.ToolGOOS || cfg.BuildContext.GOARCH != base.ToolGOARCH {
 			// Install cross-compiled binaries to subdirectories of bin.
@@ -1300,31 +1313,37 @@
 	// Build augmented import list to add implicit dependencies.
 	// Be careful not to add imports twice, just to avoid confusion.
 	importPaths := p.Imports
-	addImport := func(path string) {
+	addImport := func(path string, forCompiler bool) {
 		for _, p := range importPaths {
 			if path == p {
 				return
 			}
 		}
 		importPaths = append(importPaths, path)
+		if forCompiler {
+			p.Internal.CompiledImports = append(p.Internal.CompiledImports, path)
+		}
 	}
 
-	// Cgo translation adds imports of "runtime/cgo" and "syscall",
+	// Cgo translation adds imports of "unsafe", "runtime/cgo" and "syscall",
 	// except for certain packages, to avoid circular dependencies.
+	if p.UsesCgo() {
+		addImport("unsafe", true)
+	}
 	if p.UsesCgo() && (!p.Standard || !cgoExclude[p.ImportPath]) && cfg.BuildContext.Compiler != "gccgo" {
-		addImport("runtime/cgo")
+		addImport("runtime/cgo", true)
 	}
 	if p.UsesCgo() && (!p.Standard || !cgoSyscallExclude[p.ImportPath]) {
-		addImport("syscall")
+		addImport("syscall", true)
 	}
 
 	// SWIG adds imports of some standard packages.
 	if p.UsesSwig() {
 		if cfg.BuildContext.Compiler != "gccgo" {
-			addImport("runtime/cgo")
+			addImport("runtime/cgo", true)
 		}
-		addImport("syscall")
-		addImport("sync")
+		addImport("syscall", true)
+		addImport("sync", true)
 
 		// TODO: The .swig and .swigcxx files can use
 		// %go_import directives to import other packages.
@@ -1333,7 +1352,7 @@
 	// The linker loads implicit dependencies.
 	if p.Name == "main" && !p.Internal.ForceLibrary {
 		for _, dep := range LinkerDeps(p) {
-			addImport(dep)
+			addImport(dep, false)
 		}
 	}
 
@@ -1706,11 +1725,31 @@
 	}
 }
 
+// LoadPackage loads the package named by arg.
+func LoadPackage(arg string, stk *ImportStack) *Package {
+	p := loadPackage(arg, stk)
+	setToolFlags(p)
+	return p
+}
+
+// LoadPackageNoFlags is like LoadPackage
+// but does not guarantee that the build tool flags are set in the result.
+// It is only for use by GOPATH-based "go get"
+// and is only appropriate for preliminary loading of packages.
+// A real load using LoadPackage or (more likely)
+// Packages, PackageAndErrors, or PackagesForBuild
+// must be done before passing the package to any build
+// steps, so that the tool flags can be set properly.
+// TODO(rsc): When GOPATH-based "go get" is removed, delete this function.
+func LoadPackageNoFlags(arg string, stk *ImportStack) *Package {
+	return loadPackage(arg, stk)
+}
+
 // loadPackage is like loadImport but is used for command-line arguments,
 // not for paths found in import statements. In addition to ordinary import paths,
 // loadPackage accepts pseudo-paths beginning with cmd/ to denote commands
 // in the Go command directory, as well as paths to those directories.
-func LoadPackage(arg string, stk *ImportStack) *Package {
+func loadPackage(arg string, stk *ImportStack) *Package {
 	if build.IsLocalImport(arg) {
 		dir := arg
 		if !filepath.IsAbs(dir) {
@@ -1771,7 +1810,7 @@
 	return LoadImport(arg, base.Cwd, nil, stk, nil, 0)
 }
 
-// packages returns the packages named by the
+// Packages returns the packages named by the
 // command line arguments 'args'. If a named package
 // cannot be loaded at all (for example, if the directory does not exist),
 // then packages prints an error and does not include that
@@ -1791,58 +1830,68 @@
 	return pkgs
 }
 
-// packagesAndErrors is like 'packages' but returns a
+// PackagesAndErrors is like 'packages' but returns a
 // *Package for every argument, even the ones that
 // cannot be loaded at all.
 // The packages that fail to load will have p.Error != nil.
-func PackagesAndErrors(args []string) []*Package {
-	if len(args) > 0 && strings.HasSuffix(args[0], ".go") {
-		return []*Package{GoFilesPackage(args)}
+func PackagesAndErrors(patterns []string) []*Package {
+	if len(patterns) > 0 && strings.HasSuffix(patterns[0], ".go") {
+		return []*Package{GoFilesPackage(patterns)}
 	}
 
-	args = ImportPaths(args)
+	matches := ImportPaths(patterns)
 	var (
 		pkgs    []*Package
 		stk     ImportStack
-		seenArg = make(map[string]bool)
 		seenPkg = make(map[*Package]bool)
 	)
 
-	for _, arg := range args {
-		if seenArg[arg] {
-			continue
+	for _, m := range matches {
+		for _, pkg := range m.Pkgs {
+			p := loadPackage(pkg, &stk)
+			p.Match = append(p.Match, m.Pattern)
+			p.Internal.CmdlinePkg = true
+			if m.Literal {
+				// Note: do not set = m.Literal unconditionally
+				// because maybe we'll see p matching both
+				// a literal and also a non-literal pattern.
+				p.Internal.CmdlinePkgLiteral = true
+			}
+			if seenPkg[p] {
+				continue
+			}
+			seenPkg[p] = true
+			pkgs = append(pkgs, p)
 		}
-		seenArg[arg] = true
-		pkg := LoadPackage(arg, &stk)
-		if seenPkg[pkg] {
-			continue
-		}
-		seenPkg[pkg] = true
-		pkgs = append(pkgs, pkg)
 	}
 
+	// Now that CmdlinePkg is set correctly,
+	// compute the effective flags for all loaded packages
+	// (not just the ones matching the patterns but also
+	// their dependencies).
+	setToolFlags(pkgs...)
+
 	return pkgs
 }
 
-func ImportPaths(args []string) []string {
-	if cmdlineMatchers == nil {
-		SetCmdlinePatterns(search.CleanImportPaths(args))
+func setToolFlags(pkgs ...*Package) {
+	for _, p := range PackageList(pkgs) {
+		p.Internal.Asmflags = BuildAsmflags.For(p)
+		p.Internal.Gcflags = BuildGcflags.For(p)
+		p.Internal.Ldflags = BuildLdflags.For(p)
+		p.Internal.Gccgoflags = BuildGccgoflags.For(p)
 	}
+}
+
+func ImportPaths(args []string) []*search.Match {
 	if ModInit(); cfg.ModulesEnabled {
 		return ModImportPaths(args)
 	}
 	return search.ImportPaths(args)
 }
 
-func ImportPathsForGoGet(args []string) []string {
-	if cmdlineMatchers == nil {
-		SetCmdlinePatterns(search.CleanImportPaths(args))
-	}
-	return search.ImportPathsNoDotExpansion(args)
-}
-
-// packagesForBuild is like 'packages' but fails if any of
-// the packages or their dependencies have errors
+// PackagesForBuild is like Packages but exits
+// if any of the packages or their dependencies have errors
 // (cannot be built).
 func PackagesForBuild(args []string) []*Package {
 	pkgs := PackagesAndErrors(args)
@@ -1890,7 +1939,6 @@
 func GoFilesPackage(gofiles []string) *Package {
 	ModInit()
 
-	// TODO: Remove this restriction.
 	for _, f := range gofiles {
 		if !strings.HasSuffix(f, ".go") {
 			base.Fatalf("named files must be .go files")
@@ -1942,6 +1990,11 @@
 	}
 
 	bp, err := ctxt.ImportDir(dir, 0)
+	if ModDirImportPath != nil {
+		// Use the effective import path of the directory
+		// for deciding visibility during pkg.load.
+		bp.ImportPath = ModDirImportPath(dir)
+	}
 	pkg := new(Package)
 	pkg.Internal.Local = true
 	pkg.Internal.CmdlineFiles = true
@@ -1951,6 +2004,7 @@
 	pkg.Internal.LocalPrefix = dirToImportPath(dir)
 	pkg.ImportPath = "command-line-arguments"
 	pkg.Target = ""
+	pkg.Match = gofiles
 
 	if pkg.Name == "main" {
 		_, elem := filepath.Split(gofiles[0])
@@ -1965,5 +2019,7 @@
 		}
 	}
 
+	setToolFlags(pkg)
+
 	return pkg
 }
diff --git a/vendor/cmd/go/internal/load/search.go b/vendor/cmd/go/internal/load/search.go
index d379c7b..cf09c7b 100644
--- a/vendor/cmd/go/internal/load/search.go
+++ b/vendor/cmd/go/internal/load/search.go
@@ -6,7 +6,6 @@
 
 import (
 	"path/filepath"
-	"runtime"
 	"strings"
 
 	"cmd/go/internal/search"
@@ -28,13 +27,7 @@
 		}
 		dir = filepath.Join(cwd, dir)
 		if pattern == "" {
-			return func(p *Package) bool {
-				// TODO(rsc): This is wrong. See golang.org/issue/25878.
-				if runtime.GOOS != "windows" {
-					return p.Dir == dir
-				}
-				return strings.EqualFold(p.Dir, dir)
-			}
+			return func(p *Package) bool { return p.Dir == dir }
 		}
 		matchPath := search.MatchPattern(pattern)
 		return func(p *Package) bool {
diff --git a/vendor/cmd/go/internal/load/test.go b/vendor/cmd/go/internal/load/test.go
index 2cc7c6c..bb9568d 100644
--- a/vendor/cmd/go/internal/load/test.go
+++ b/vendor/cmd/go/internal/load/test.go
@@ -342,6 +342,8 @@
 			p1.ForTest = preal.ImportPath
 			p1.Internal.Imports = make([]*Package, len(p.Internal.Imports))
 			copy(p1.Internal.Imports, p.Internal.Imports)
+			p1.Imports = make([]string, len(p.Imports))
+			copy(p1.Imports, p.Imports)
 			p = p1
 			p.Target = ""
 		}
diff --git a/vendor/cmd/go/internal/modcmd/download.go b/vendor/cmd/go/internal/modcmd/download.go
new file mode 100644
index 0000000..cf42eff
--- /dev/null
+++ b/vendor/cmd/go/internal/modcmd/download.go
@@ -0,0 +1,133 @@
+// Copyright 2018 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package modcmd
+
+import (
+	"cmd/go/internal/base"
+	"cmd/go/internal/modfetch"
+	"cmd/go/internal/modload"
+	"cmd/go/internal/module"
+	"cmd/go/internal/par"
+	"encoding/json"
+	"os"
+)
+
+var cmdDownload = &base.Command{
+	UsageLine: "go mod download [-dir] [-json] [modules]",
+	Short:     "download modules to local cache",
+	Long: `
+Download downloads the named modules, which can be module patterns selecting
+dependencies of the main module or module queries of the form path@version.
+With no arguments, download applies to all dependencies of the main module.
+
+The go command will automatically download modules as needed during ordinary
+execution. The "go mod download" command is useful mainly for pre-filling
+the local cache or to compute the answers for a Go module proxy.
+
+By default, download reports errors to standard error but is otherwise silent.
+The -json flag causes download to print a sequence of JSON objects
+to standard output, describing each downloaded module (or failure),
+corresponding to this Go struct:
+
+    type Module struct {
+        Path     string // module path
+        Version  string // module version
+        Error    string // error loading module
+        Info     string // absolute path to cached .info file
+        GoMod    string // absolute path to cached .mod file
+        Zip      string // absolute path to cached .zip file
+        Dir      string // absolute path to cached source root directory
+        Sum      string // checksum for path, version (as in go.sum)
+        GoModSum string // checksum for go.mod (as in go.sum)
+    }
+
+See 'go help modules' for more about module queries.
+	`,
+}
+
+var downloadJSON = cmdDownload.Flag.Bool("json", false, "")
+
+func init() {
+	cmdDownload.Run = runDownload // break init cycle
+}
+
+type moduleJSON struct {
+	Path     string `json:",omitempty"`
+	Version  string `json:",omitempty"`
+	Error    string `json:",omitempty"`
+	Info     string `json:",omitempty"`
+	GoMod    string `json:",omitempty"`
+	Zip      string `json:",omitempty"`
+	Dir      string `json:",omitempty"`
+	Sum      string `json:",omitempty"`
+	GoModSum string `json:",omitempty"`
+}
+
+func runDownload(cmd *base.Command, args []string) {
+	if len(args) == 0 {
+		args = []string{"all"}
+	}
+
+	var mods []*moduleJSON
+	var work par.Work
+	listU := false
+	listVersions := false
+	for _, info := range modload.ListModules(args, listU, listVersions) {
+		if info.Replace != nil {
+			info = info.Replace
+		}
+		if info.Version == "" {
+			continue
+		}
+		m := &moduleJSON{
+			Path:    info.Path,
+			Version: info.Version,
+		}
+		mods = append(mods, m)
+		work.Add(m)
+	}
+
+	work.Do(10, func(item interface{}) {
+		m := item.(*moduleJSON)
+		var err error
+		m.Info, err = modfetch.InfoFile(m.Path, m.Version)
+		if err != nil {
+			m.Error = err.Error()
+			return
+		}
+		m.GoMod, err = modfetch.GoModFile(m.Path, m.Version)
+		if err != nil {
+			m.Error = err.Error()
+			return
+		}
+		m.GoModSum, err = modfetch.GoModSum(m.Path, m.Version)
+		if err != nil {
+			m.Error = err.Error()
+			return
+		}
+		mod := module.Version{Path: m.Path, Version: m.Version}
+		m.Zip, err = modfetch.DownloadZip(mod)
+		if err != nil {
+			m.Error = err.Error()
+			return
+		}
+		m.Sum = modfetch.Sum(mod)
+		m.Dir, err = modfetch.Download(mod)
+		if err != nil {
+			m.Error = err.Error()
+			return
+		}
+	})
+
+	if *downloadJSON {
+		for _, m := range mods {
+			b, err := json.MarshalIndent(m, "", "\t")
+			if err != nil {
+				base.Fatalf("%v", err)
+			}
+			os.Stdout.Write(append(b, '\n'))
+		}
+	}
+}
diff --git a/vendor/cmd/go/internal/modcmd/fix.go b/vendor/cmd/go/internal/modcmd/fix.go
deleted file mode 100644
index bfb5145..0000000
--- a/vendor/cmd/go/internal/modcmd/fix.go
+++ /dev/null
@@ -1,65 +0,0 @@
-// Copyright 2018 The Go Authors. All rights reserved.
-// Use of this source code is governed by a BSD-style
-// license that can be found in the LICENSE file.
-
-// go mod fix
-
-package modcmd
-
-import (
-	"cmd/go/internal/base"
-	"cmd/go/internal/modload"
-)
-
-var cmdFix = &base.Command{
-	UsageLine: "go mod fix",
-	Short:     "make go.mod semantically consistent",
-	Long: `
-Fix updates go.mod to use canonical version identifiers and
-to be semantically consistent. For example, consider this go.mod file:
-
-	module M
-
-	require (
-		A v1
-		B v1.0.0
-		C v1.0.0
-		D v1.2.3
-		E dev
-	)
-
-	exclude D v1.2.3
-
-First, fix rewrites non-canonical version identifiers to semver form, so
-A's v1 becomes v1.0.0 and E's dev becomes the pseudo-version for the latest
-commit on the dev branch, perhaps v0.0.0-20180523231146-b3f5c0f6e5f1.
-
-Next, fix updates requirements to respect exclusions, so the requirement
-on the excluded D v1.2.3 is updated to use the next available version of D,
-perhaps D v1.2.4 or D v1.3.0.
-
-Finally, fix removes redundant or misleading requirements.
-For example, if A v1.0.0 itself requires B v1.2.0 and C v1.0.0, then go.mod's
-requirement of B v1.0.0 is misleading (superseded by A's need for v1.2.0),
-and its requirement of C v1.0.0 is redundant (implied by A's need for the
-same version), so both will be removed. If module M contains packages
-that directly import packages from B or C, then the requirements will be
-kept but updated to the actual versions being used.
-
-Although fix runs the fix-up operation in isolation, the fix-up also
-runs automatically any time a go command uses the module graph,
-to update go.mod to reflect reality. Because the module graph defines
-the meaning of import statements, any commands that load packages
-also use and therefore fix the module graph. For example,
-go build, go get, go install, go list, go test, go mod graph, go mod tidy,
-and other commands all effectively imply go mod fix.
-	`,
-	Run: runFix,
-}
-
-func runFix(cmd *base.Command, args []string) {
-	if len(args) != 0 {
-		base.Fatalf("go mod fix: fix takes no arguments")
-	}
-	modload.LoadBuildList() // writes go.mod
-}
diff --git a/vendor/cmd/go/internal/modcmd/mod.go b/vendor/cmd/go/internal/modcmd/mod.go
index c1a0ddc..f150cc9 100644
--- a/vendor/cmd/go/internal/modcmd/mod.go
+++ b/vendor/cmd/go/internal/modcmd/mod.go
@@ -19,12 +19,13 @@
 	`,
 
 	Commands: []*base.Command{
+		cmdDownload,
 		cmdEdit,
-		cmdFix,
 		cmdGraph,
 		cmdInit,
 		cmdTidy,
 		cmdVendor,
 		cmdVerify,
+		cmdWhy,
 	},
 }
diff --git a/vendor/cmd/go/internal/modcmd/tidy.go b/vendor/cmd/go/internal/modcmd/tidy.go
index 54f47e7..f2063a9 100644
--- a/vendor/cmd/go/internal/modcmd/tidy.go
+++ b/vendor/cmd/go/internal/modcmd/tidy.go
@@ -44,10 +44,11 @@
 
 	// LoadALL adds missing modules.
 	// Remove unused modules.
-	used := map[module.Version]bool{modload.Target: true}
+	used := make(map[module.Version]bool)
 	for _, pkg := range modload.LoadALL() {
 		used[modload.PackageModule(pkg)] = true
 	}
+	used[modload.Target] = true // note: LoadALL initializes Target
 
 	inGoMod := make(map[string]bool)
 	for _, r := range modload.ModFile().Require {
diff --git a/vendor/cmd/go/internal/modcmd/why.go b/vendor/cmd/go/internal/modcmd/why.go
new file mode 100644
index 0000000..03e0a03
--- /dev/null
+++ b/vendor/cmd/go/internal/modcmd/why.go
@@ -0,0 +1,121 @@
+// Copyright 2018 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package modcmd
+
+import (
+	"cmd/go/internal/base"
+	"cmd/go/internal/modload"
+	"cmd/go/internal/module"
+	"fmt"
+	"strings"
+)
+
+var cmdWhy = &base.Command{
+	UsageLine: "go mod why [-m] [-vendor] packages...",
+	Short:     "explain why packages or modules are needed",
+	Long: `
+Why shows a shortest path in the import graph from the main module to
+each of the listed packages. If the -m flag is given, why treats the
+arguments as a list of modules and finds a path to any package in each
+of the modules.
+
+By default, why queries the graph of packages matched by "go list all",
+which includes tests for reachable packages. The -vendor flag causes why
+to exclude tests of dependencies.
+
+The output is a sequence of stanzas, one for each package or module
+name on the command line, separated by blank lines. Each stanza begins
+with a comment line "# package" or "# module" giving the target
+package or module. Subsequent lines give a path through the import
+graph, one package per line. If the package or module is not
+referenced from the main module, the stanza will display a single
+parenthesized note indicating that fact.
+
+For example:
+
+	$ go mod why golang.org/x/text/language golang.org/x/text/encoding
+	# golang.org/x/text/language
+	rsc.io/quote
+	rsc.io/sampler
+	golang.org/x/text/language
+
+	# golang.org/x/text/encoding
+	(main module does not need package golang.org/x/text/encoding)
+	$
+	`,
+}
+
+var (
+	whyM      = cmdWhy.Flag.Bool("m", false, "")
+	whyVendor = cmdWhy.Flag.Bool("vendor", false, "")
+)
+
+func init() {
+	cmdWhy.Run = runWhy // break init cycle
+}
+
+func runWhy(cmd *base.Command, args []string) {
+	loadALL := modload.LoadALL
+	if *whyVendor {
+		loadALL = modload.LoadVendor
+	}
+	if *whyM {
+		listU := false
+		listVersions := false
+		for _, arg := range args {
+			if strings.Contains(arg, "@") {
+				base.Fatalf("go mod why: module query not allowed")
+			}
+		}
+		mods := modload.ListModules(args, listU, listVersions)
+		byModule := make(map[module.Version][]string)
+		for _, path := range loadALL() {
+			m := modload.PackageModule(path)
+			if m.Path != "" {
+				byModule[m] = append(byModule[m], path)
+			}
+		}
+		sep := ""
+		for _, m := range mods {
+			best := ""
+			bestDepth := 1000000000
+			for _, path := range byModule[module.Version{Path: m.Path, Version: m.Version}] {
+				d := modload.WhyDepth(path)
+				if d > 0 && d < bestDepth {
+					best = path
+					bestDepth = d
+				}
+			}
+			why := modload.Why(best)
+			if why == "" {
+				vendoring := ""
+				if *whyVendor {
+					vendoring = " to vendor"
+				}
+				why = "(main module does not need" + vendoring + " module " + m.Path + ")\n"
+			}
+			fmt.Printf("%s# %s\n%s", sep, m.Path, why)
+			sep = "\n"
+		}
+	} else {
+		matches := modload.ImportPaths(args) // resolve to packages
+		loadALL()                            // rebuild graph, from main module (not from named packages)
+		sep := ""
+		for _, m := range matches {
+			for _, path := range m.Pkgs {
+				why := modload.Why(path)
+				if why == "" {
+					vendoring := ""
+					if *whyVendor {
+						vendoring = " to vendor"
+					}
+					why = "(main module does not need" + vendoring + " package " + path + ")\n"
+				}
+				fmt.Printf("%s# %s\n%s", sep, path, why)
+				sep = "\n"
+			}
+		}
+	}
+}
diff --git a/vendor/cmd/go/internal/modconv/convert_test.go b/vendor/cmd/go/internal/modconv/convert_test.go
index f430380..ad27abb 100644
--- a/vendor/cmd/go/internal/modconv/convert_test.go
+++ b/vendor/cmd/go/internal/modconv/convert_test.go
@@ -61,28 +61,36 @@
 		vers  string
 		gomod string
 	}{
-		{
-			// Gopkg.lock parsing.
-			"github.com/golang/dep", "v0.4.0",
-			`module github.com/golang/dep
+		/*
+			Different versions of git seem to find or not find
+			github.com/Masterminds/semver's a93e51b5a57e,
+			which is an unmerged pull request.
+			We'd rather not provide access to unmerged pull requests,
+			so the line is removed from the golden file here,
+			but some git commands still find it somehow.
 
-			require (
-				github.com/Masterminds/semver v0.0.0-20170726230514-a93e51b5a57e
-				github.com/Masterminds/vcs v1.11.1
-				github.com/armon/go-radix v0.0.0-20160115234725-4239b77079c7
-				github.com/boltdb/bolt v1.3.1
-				github.com/go-yaml/yaml v0.0.0-20170407172122-cd8b52f8269e
-				github.com/golang/protobuf v0.0.0-20170901042739-5afd06f9d81a
-				github.com/jmank88/nuts v0.3.0
-				github.com/nightlyone/lockfile v0.0.0-20170707060451-e83dc5e7bba0
-				github.com/pelletier/go-toml v0.0.0-20171218135716-b8b5e7696574
-				github.com/pkg/errors v0.8.0
-				github.com/sdboyer/constext v0.0.0-20170321163424-836a14457353
-				golang.org/x/net v0.0.0-20170828231752-66aacef3dd8a
-				golang.org/x/sync v0.0.0-20170517211232-f52d1811a629
-				golang.org/x/sys v0.0.0-20170830134202-bb24a47a89ea
-			)`,
-		},
+			{
+				// Gopkg.lock parsing.
+				"github.com/golang/dep", "v0.4.0",
+				`module github.com/golang/dep
+
+				require (
+					github.com/Masterminds/vcs v1.11.1
+					github.com/armon/go-radix v0.0.0-20160115234725-4239b77079c7
+					github.com/boltdb/bolt v1.3.1
+					github.com/go-yaml/yaml v0.0.0-20170407172122-cd8b52f8269e
+					github.com/golang/protobuf v0.0.0-20170901042739-5afd06f9d81a
+					github.com/jmank88/nuts v0.3.0
+					github.com/nightlyone/lockfile v0.0.0-20170707060451-e83dc5e7bba0
+					github.com/pelletier/go-toml v0.0.0-20171218135716-b8b5e7696574
+					github.com/pkg/errors v0.8.0
+					github.com/sdboyer/constext v0.0.0-20170321163424-836a14457353
+					golang.org/x/net v0.0.0-20170828231752-66aacef3dd8a
+					golang.org/x/sync v0.0.0-20170517211232-f52d1811a629
+					golang.org/x/sys v0.0.0-20170830134202-bb24a47a89ea
+				)`,
+			},
+		*/
 
 		// TODO: https://github.com/docker/distribution uses vendor.conf
 
diff --git a/vendor/cmd/go/internal/modfetch/cache.go b/vendor/cmd/go/internal/modfetch/cache.go
index b801f64..1f9cc96 100644
--- a/vendor/cmd/go/internal/modfetch/cache.go
+++ b/vendor/cmd/go/internal/modfetch/cache.go
@@ -232,6 +232,23 @@
 	return repo.Stat(rev)
 }
 
+// InfoFile is like Stat but returns the name of the file containing
+// the cached information.
+func InfoFile(path, version string) (string, error) {
+	if !semver.IsValid(version) {
+		return "", fmt.Errorf("invalid version %q", version)
+	}
+	if _, err := Stat(path, version); err != nil {
+		return "", err
+	}
+	// Stat should have populated the disk cache for us.
+	file, _, err := readDiskStat(path, version)
+	if err != nil {
+		return "", err
+	}
+	return file, nil
+}
+
 // GoMod is like Lookup(path).GoMod(rev) but avoids the
 // repository path resolution in Lookup if the result is
 // already cached on local disk.
@@ -256,6 +273,40 @@
 	return repo.GoMod(rev)
 }
 
+// GoModFile is like GoMod but returns the name of the file containing
+// the cached information.
+func GoModFile(path, version string) (string, error) {
+	if !semver.IsValid(version) {
+		return "", fmt.Errorf("invalid version %q", version)
+	}
+	if _, err := GoMod(path, version); err != nil {
+		return "", err
+	}
+	// GoMod should have populated the disk cache for us.
+	file, _, err := readDiskGoMod(path, version)
+	if err != nil {
+		return "", err
+	}
+	return file, nil
+}
+
+// GoModSum returns the go.sum entry for the module version's go.mod file.
+// (That is, it returns the entry listed in go.sum as "path version/go.mod".)
+func GoModSum(path, version string) (string, error) {
+	if !semver.IsValid(version) {
+		return "", fmt.Errorf("invalid version %q", version)
+	}
+	data, err := GoMod(path, version)
+	if err != nil {
+		return "", err
+	}
+	sum, err := goModSum(data)
+	if err != nil {
+		return "", err
+	}
+	return sum, nil
+}
+
 var errNotCached = fmt.Errorf("not in cache")
 
 // readDiskStat reads a cached stat result from disk,
@@ -274,6 +325,13 @@
 	if err := json.Unmarshal(data, info); err != nil {
 		return file, nil, errNotCached
 	}
+	// The disk might have stale .info files that have Name and Short fields set.
+	// We want to canonicalize to .info files with those fields omitted.
+	// Remarshal and update the cache file if needed.
+	data2, err := json.Marshal(info)
+	if err == nil && !bytes.Equal(data2, data) {
+		writeDiskCache(file, data)
+	}
 	return file, info, nil
 }
 
diff --git a/vendor/cmd/go/internal/modfetch/codehost/git.go b/vendor/cmd/go/internal/modfetch/codehost/git.go
index 0f159bd..87940a8 100644
--- a/vendor/cmd/go/internal/modfetch/codehost/git.go
+++ b/vendor/cmd/go/internal/modfetch/codehost/git.go
@@ -347,27 +347,19 @@
 		if err == nil {
 			return r.statLocal(rev, ref)
 		}
-		if !strings.Contains(err.Error(), "unadvertised object") && !strings.Contains(err.Error(), "no such remote ref") && !strings.Contains(err.Error(), "does not support shallow") {
-			return nil, err
-		}
+		// Don't try to be smart about parsing the error.
+		// It's too complex and varies too much by git version.
+		// No matter what went wrong, fall back to a complete fetch.
 	}
 
 	// Last resort.
 	// Fetch all heads and tags and hope the hash we want is in the history.
 	if r.fetchLevel < fetchAll {
+		// TODO(bcmills): should we wait to upgrade fetchLevel until after we check
+		// err? If there is a temporary server error, we want subsequent fetches to
+		// try again instead of proceeding with an incomplete repo.
 		r.fetchLevel = fetchAll
-
-		// To work around a protocol version 2 bug that breaks --unshallow,
-		// add -c protocol.version=0.
-		// TODO(rsc): The bug is believed to be server-side, meaning only
-		// on Google's Git servers. Once the servers are fixed, drop the
-		// protocol.version=0. See Google-internal bug b/110495752.
-		var protoFlag []string
-		unshallowFlag := unshallow(r.dir)
-		if len(unshallowFlag) > 0 {
-			protoFlag = []string{"-c", "protocol.version=0"}
-		}
-		if _, err := Run(r.dir, "git", protoFlag, "fetch", unshallowFlag, "-f", r.remote, "refs/heads/*:refs/heads/*", "refs/tags/*:refs/tags/*"); err != nil {
+		if err := r.fetchUnshallow("refs/heads/*:refs/heads/*", "refs/tags/*:refs/tags/*"); err != nil {
 			return nil, err
 		}
 	}
@@ -375,6 +367,21 @@
 	return r.statLocal(rev, rev)
 }
 
+func (r *gitRepo) fetchUnshallow(refSpecs ...string) error {
+	// To work around a protocol version 2 bug that breaks --unshallow,
+	// add -c protocol.version=0.
+	// TODO(rsc): The bug is believed to be server-side, meaning only
+	// on Google's Git servers. Once the servers are fixed, drop the
+	// protocol.version=0. See Google-internal bug b/110495752.
+	var protoFlag []string
+	unshallowFlag := unshallow(r.dir)
+	if len(unshallowFlag) > 0 {
+		protoFlag = []string{"-c", "protocol.version=0"}
+	}
+	_, err := Run(r.dir, "git", protoFlag, "fetch", unshallowFlag, "-f", r.remote, refSpecs)
+	return err
+}
+
 // statLocal returns a RevInfo describing rev in the local git repository.
 // It uses version as info.Version.
 func (r *gitRepo) statLocal(version, rev string) (*RevInfo, error) {
@@ -512,6 +519,18 @@
 		return nil, err
 	}
 
+	// TODO(bcmills): after the 1.11 freeze, replace the block above with:
+	//	if r.fetchLevel <= fetchSome {
+	//		r.fetchLevel = fetchSome
+	//		var refs []string
+	//		for _, tag := range redo {
+	//			refs = append(refs, "refs/tags/"+tag+":refs/tags/"+tag)
+	//		}
+	//		if _, err := Run(r.dir, "git", "fetch", "--update-shallow", "-f", r.remote, refs); err != nil {
+	//			return nil, err
+	//		}
+	//	}
+
 	if _, err := r.readFileRevs(redo, file, files); err != nil {
 		return nil, err
 	}
@@ -603,15 +622,65 @@
 }
 
 func (r *gitRepo) RecentTag(rev, prefix string) (tag string, err error) {
-	_, err = r.Stat(rev)
+	info, err := r.Stat(rev)
 	if err != nil {
 		return "", err
 	}
-	out, err := Run(r.dir, "git", "describe", "--first-parent", "--tags", "--always", "--abbrev=0", "--match", prefix+"v[0-9]*.[0-9]*.[0-9]*", "--tags", rev)
+	rev = info.Name // expand hash prefixes
+
+	// describe sets tag and err using 'git describe' and reports whether the
+	// result is definitive.
+	describe := func() (definitive bool) {
+		var out []byte
+		out, err = Run(r.dir, "git", "describe", "--first-parent", "--always", "--abbrev=0", "--match", prefix+"v[0-9]*.[0-9]*.[0-9]*", "--tags", rev)
+		if err != nil {
+			return true // Because we use "--always", describe should never fail.
+		}
+
+		tag = string(bytes.TrimSpace(out))
+		return tag != "" && !AllHex(tag)
+	}
+
+	if describe() {
+		return tag, err
+	}
+
+	// Git didn't find a version tag preceding the requested rev.
+	// See whether any plausible tag exists.
+	tags, err := r.Tags(prefix + "v")
 	if err != nil {
 		return "", err
 	}
-	return strings.TrimSpace(string(out)), nil
+	if len(tags) == 0 {
+		return "", nil
+	}
+
+	// There are plausible tags, but we don't know if rev is a descendent of any of them.
+	// Fetch the history to find out.
+
+	r.mu.Lock()
+	defer r.mu.Unlock()
+
+	if r.fetchLevel < fetchAll {
+		// Fetch all heads and tags and see if that gives us enough history.
+		if err := r.fetchUnshallow("refs/heads/*:refs/heads/*", "refs/tags/*:refs/tags/*"); err != nil {
+			return "", err
+		}
+		r.fetchLevel = fetchAll
+	}
+
+	// If we've reached this point, we have all of the commits that are reachable
+	// from all heads and tags.
+	//
+	// The only refs we should be missing are those that are no longer reachable
+	// (or never were reachable) from any branch or tag, including the master
+	// branch, and we don't want to resolve them anyway (they're probably
+	// unreachable for a reason).
+	//
+	// Try one last time in case some other goroutine fetched rev while we were
+	// waiting on r.mu.
+	describe()
+	return tag, err
 }
 
 func (r *gitRepo) ReadZip(rev, subdir string, maxSize int64) (zip io.ReadCloser, actualSubdir string, err error) {
diff --git a/vendor/cmd/go/internal/modfetch/codehost/shell b/vendor/cmd/go/internal/modfetch/codehost/shell
deleted file mode 100755
index 490aa6c..0000000
--- a/vendor/cmd/go/internal/modfetch/codehost/shell
+++ /dev/null
Binary files differ
diff --git a/vendor/cmd/go/internal/modfetch/codehost/vcs.go b/vendor/cmd/go/internal/modfetch/codehost/vcs.go
index 03def8e..9e862a0 100644
--- a/vendor/cmd/go/internal/modfetch/codehost/vcs.go
+++ b/vendor/cmd/go/internal/modfetch/codehost/vcs.go
@@ -22,6 +22,17 @@
 	"cmd/go/internal/str"
 )
 
+// A VCSError indicates an error using a version control system.
+// The implication of a VCSError is that we know definitively where
+// to get the code, but we can't access it due to the error.
+// The caller should report this error instead of continuing to probe
+// other possible module paths.
+type VCSError struct {
+	Err error
+}
+
+func (e *VCSError) Error() string { return e.Err.Error() }
+
 func NewRepo(vcs, remote string) (Repo, error) {
 	type key struct {
 		vcs    string
@@ -33,6 +44,9 @@
 	}
 	c := vcsRepoCache.Do(key{vcs, remote}, func() interface{} {
 		repo, err := newVCSRepo(vcs, remote)
+		if err != nil {
+			err = &VCSError{err}
+		}
 		return cached{repo, err}
 	}).(cached)
 
diff --git a/vendor/cmd/go/internal/modfetch/coderepo.go b/vendor/cmd/go/internal/modfetch/coderepo.go
index c45833c..9cf0e91 100644
--- a/vendor/cmd/go/internal/modfetch/coderepo.go
+++ b/vendor/cmd/go/internal/modfetch/coderepo.go
@@ -86,6 +86,13 @@
 }
 
 func (r *codeRepo) Versions(prefix string) ([]string, error) {
+	// Special case: gopkg.in/macaroon-bakery.v2-unstable
+	// does not use the v2 tags (those are for macaroon-bakery.v2).
+	// It has no possible tags at all.
+	if strings.HasPrefix(r.modPath, "gopkg.in/") && strings.HasSuffix(r.modPath, "-unstable") {
+		return nil, nil
+	}
+
 	p := prefix
 	if r.codeDir != "" {
 		p = r.codeDir + "/" + p
diff --git a/vendor/cmd/go/internal/modfetch/coderepo_test.go b/vendor/cmd/go/internal/modfetch/coderepo_test.go
index c467051..79b8278 100644
--- a/vendor/cmd/go/internal/modfetch/coderepo_test.go
+++ b/vendor/cmd/go/internal/modfetch/coderepo_test.go
@@ -228,10 +228,9 @@
 		path:    "swtch.com/testmod",
 		rev:     "v1.0.0",
 		version: "v1.0.0",
-		name:    "v1.0.0",
-		short:   "v1.0.0",
-		time:    time.Date(1972, 7, 18, 12, 34, 56, 0, time.UTC),
-		gomod:   "module \"swtch.com/testmod\"\n",
+		// NO name or short - we intentionally ignore those in the proxy protocol
+		time:  time.Date(1972, 7, 18, 12, 34, 56, 0, time.UTC),
+		gomod: "module \"swtch.com/testmod\"\n",
 	},
 	{
 		// redirect to googlesource
diff --git a/vendor/cmd/go/internal/modfetch/fetch.go b/vendor/cmd/go/internal/modfetch/fetch.go
index b4944af..2e26bac 100644
--- a/vendor/cmd/go/internal/modfetch/fetch.go
+++ b/vendor/cmd/go/internal/modfetch/fetch.go
@@ -17,6 +17,7 @@
 	"sync"
 
 	"cmd/go/internal/base"
+	"cmd/go/internal/cfg"
 	"cmd/go/internal/dirhash"
 	"cmd/go/internal/module"
 	"cmd/go/internal/par"
@@ -46,24 +47,10 @@
 			return cached{"", err}
 		}
 		if files, _ := ioutil.ReadDir(dir); len(files) == 0 {
-			zipfile, err := CachePath(mod, "zip")
+			zipfile, err := DownloadZip(mod)
 			if err != nil {
 				return cached{"", err}
 			}
-			if _, err := os.Stat(zipfile); err == nil {
-				// Use it.
-				// This should only happen if the mod/cache directory is preinitialized
-				// or if pkg/mod/path was removed but not pkg/mod/cache/download.
-				fmt.Fprintf(os.Stderr, "go: extracting %s %s\n", mod.Path, mod.Version)
-			} else {
-				if err := os.MkdirAll(filepath.Dir(zipfile), 0777); err != nil {
-					return cached{"", err}
-				}
-				fmt.Fprintf(os.Stderr, "go: downloading %s %s\n", mod.Path, mod.Version)
-				if err := downloadZip(mod, zipfile); err != nil {
-					return cached{"", err}
-				}
-			}
 			modpath := mod.Path + "@" + mod.Version
 			if err := Unzip(dir, zipfile, modpath, 0); err != nil {
 				fmt.Fprintf(os.Stderr, "-> %s\n", err)
@@ -76,6 +63,46 @@
 	return c.dir, c.err
 }
 
+var downloadZipCache par.Cache
+
+// DownloadZip downloads the specific module version to the
+// local zip cache and returns the name of the zip file.
+func DownloadZip(mod module.Version) (zipfile string, err error) {
+	// The par.Cache here avoids duplicate work but also
+	// avoids conflicts from simultaneous calls by multiple goroutines
+	// for the same version.
+	type cached struct {
+		zipfile string
+		err     error
+	}
+	c := downloadZipCache.Do(mod, func() interface{} {
+		zipfile, err := CachePath(mod, "zip")
+		if err != nil {
+			return cached{"", err}
+		}
+		if _, err := os.Stat(zipfile); err == nil {
+			// Use it.
+			// This should only happen if the mod/cache directory is preinitialized
+			// or if pkg/mod/path was removed but not pkg/mod/cache/download.
+			if cfg.CmdName != "mod download" {
+				fmt.Fprintf(os.Stderr, "go: extracting %s %s\n", mod.Path, mod.Version)
+			}
+		} else {
+			if err := os.MkdirAll(filepath.Dir(zipfile), 0777); err != nil {
+				return cached{"", err}
+			}
+			if cfg.CmdName != "mod download" {
+				fmt.Fprintf(os.Stderr, "go: downloading %s %s\n", mod.Path, mod.Version)
+			}
+			if err := downloadZip(mod, zipfile); err != nil {
+				return cached{"", err}
+			}
+		}
+		return cached{zipfile, nil}
+	}).(cached)
+	return c.zipfile, c.err
+}
+
 func downloadZip(mod module.Version, target string) error {
 	repo, err := Lookup(mod.Path)
 	if err != nil {
@@ -226,12 +253,17 @@
 	checkOneSum(mod, h)
 }
 
+// goModSum returns the checksum for the go.mod contents.
+func goModSum(data []byte) (string, error) {
+	return dirhash.Hash1([]string{"go.mod"}, func(string) (io.ReadCloser, error) {
+		return ioutil.NopCloser(bytes.NewReader(data)), nil
+	})
+}
+
 // checkGoMod checks the given module's go.mod checksum;
 // data is the go.mod content.
 func checkGoMod(path, version string, data []byte) {
-	h, err := dirhash.Hash1([]string{"go.mod"}, func(string) (io.ReadCloser, error) {
-		return ioutil.NopCloser(bytes.NewReader(data)), nil
-	})
+	h, err := goModSum(data)
 	if err != nil {
 		base.Fatalf("go: verifying %s %s go.mod: %v", path, version, err)
 	}
diff --git a/vendor/cmd/go/internal/modfetch/proxy.go b/vendor/cmd/go/internal/modfetch/proxy.go
index 693eb18..5f856b8 100644
--- a/vendor/cmd/go/internal/modfetch/proxy.go
+++ b/vendor/cmd/go/internal/modfetch/proxy.go
@@ -55,7 +55,7 @@
 
 To avoid problems when serving from case-sensitive file systems,
 the <module> and <version> elements are case-encoded, replacing every
-uppercase letter with an exclamation mark followed by the correponding
+uppercase letter with an exclamation mark followed by the corresponding
 lower-case letter: github.com/Azure encodes as github.com/!azure.
 
 The JSON-formatted metadata about a given module corresponds to
diff --git a/vendor/cmd/go/internal/modfetch/pseudo.go b/vendor/cmd/go/internal/modfetch/pseudo.go
index 990fa54..32c7bf8 100644
--- a/vendor/cmd/go/internal/modfetch/pseudo.go
+++ b/vendor/cmd/go/internal/modfetch/pseudo.go
@@ -49,6 +49,7 @@
 	if major == "" {
 		major = "v0"
 	}
+	major = strings.TrimSuffix(major, "-unstable") // make gopkg.in/macaroon-bakery.v2-unstable use "v2"
 	segment := fmt.Sprintf("%s-%s", t.UTC().Format("20060102150405"), rev)
 	build := semver.Build(older)
 	older = semver.Canonical(older)
diff --git a/vendor/cmd/go/internal/modfetch/repo.go b/vendor/cmd/go/internal/modfetch/repo.go
index f6f47bb..0ea8c1f 100644
--- a/vendor/cmd/go/internal/modfetch/repo.go
+++ b/vendor/cmd/go/internal/modfetch/repo.go
@@ -55,9 +55,12 @@
 // A Rev describes a single revision in a module repository.
 type RevInfo struct {
 	Version string    // version string
-	Name    string    // complete ID in underlying repository
-	Short   string    // shortened ID, for use in pseudo-version
 	Time    time.Time // commit time
+
+	// These fields are used for Stat of arbitrary rev,
+	// but they are not recorded when talking about module versions.
+	Name  string `json:"-"` // complete ID in underlying repository
+	Short string `json:"-"` // shortened ID, for use in pseudo-version
 }
 
 // Re: module paths, import paths, repository roots, and lookups
@@ -213,7 +216,11 @@
 		return lookupProxy(path)
 	}
 
-	rr, err := get.RepoRootForImportPath(path, get.PreferMod, web.Secure)
+	security := web.Secure
+	if get.Insecure {
+		security = web.Insecure
+	}
+	rr, err := get.RepoRootForImportPath(path, get.PreferMod, security)
 	if err != nil {
 		// We don't know where to find code for a module with this path.
 		return nil, err
@@ -234,6 +241,9 @@
 func lookupCodeRepo(rr *get.RepoRoot) (codehost.Repo, error) {
 	code, err := codehost.NewRepo(rr.VCS, rr.Repo)
 	if err != nil {
+		if _, ok := err.(*codehost.VCSError); ok {
+			return nil, err
+		}
 		return nil, fmt.Errorf("lookup %s: %v", rr.Root, err)
 	}
 	return code, nil
@@ -251,7 +261,11 @@
 	// Note: Because we are converting a code reference from a legacy
 	// version control system, we ignore meta tags about modules
 	// and use only direct source control entries (get.IgnoreMod).
-	rr, err := get.RepoRootForImportPath(path, get.IgnoreMod, web.Secure)
+	security := web.Secure
+	if get.Insecure {
+		security = web.Insecure
+	}
+	rr, err := get.RepoRootForImportPath(path, get.IgnoreMod, security)
 	if err != nil {
 		return nil, nil, err
 	}
diff --git a/vendor/cmd/go/internal/modfile/rule.go b/vendor/cmd/go/internal/modfile/rule.go
index f669575..e11f0a6 100644
--- a/vendor/cmd/go/internal/modfile/rule.go
+++ b/vendor/cmd/go/internal/modfile/rule.go
@@ -250,7 +250,7 @@
 			arrow = 1
 		}
 		if len(args) < arrow+2 || len(args) > arrow+3 || args[arrow] != "=>" {
-			fmt.Fprintf(errs, "%s:%d: usage: %s module/path [v1.2.3] => other/module v1.4\n\t or %s module/path [v1.2.3] => ../local/directory", f.Syntax.Name, line.Start.Line, verb, verb)
+			fmt.Fprintf(errs, "%s:%d: usage: %s module/path [v1.2.3] => other/module v1.4\n\t or %s module/path [v1.2.3] => ../local/directory\n", f.Syntax.Name, line.Start.Line, verb, verb)
 			return
 		}
 		s, err := parseString(&args[0])
@@ -287,11 +287,11 @@
 		nv := ""
 		if len(args) == arrow+2 {
 			if !IsDirectoryPath(ns) {
-				fmt.Fprintf(errs, "%s:%d: replacement module without version must be directory path (rooted or starting with ./ or ../)", f.Syntax.Name, line.Start.Line)
+				fmt.Fprintf(errs, "%s:%d: replacement module without version must be directory path (rooted or starting with ./ or ../)\n", f.Syntax.Name, line.Start.Line)
 				return
 			}
 			if filepath.Separator == '/' && strings.Contains(ns, `\`) {
-				fmt.Fprintf(errs, "%s:%d: replacement directory appears to be Windows path (on a non-windows system)", f.Syntax.Name, line.Start.Line)
+				fmt.Fprintf(errs, "%s:%d: replacement directory appears to be Windows path (on a non-windows system)\n", f.Syntax.Name, line.Start.Line)
 				return
 			}
 		}
@@ -303,7 +303,7 @@
 				return
 			}
 			if IsDirectoryPath(ns) {
-				fmt.Fprintf(errs, "%s:%d: replacement module directory path %q cannot have version", f.Syntax.Name, line.Start.Line, ns)
+				fmt.Fprintf(errs, "%s:%d: replacement module directory path %q cannot have version\n", f.Syntax.Name, line.Start.Line, ns)
 				return
 			}
 		}
diff --git a/vendor/cmd/go/internal/modget/get.go b/vendor/cmd/go/internal/modget/get.go
index e8b0857..90a5bd8 100644
--- a/vendor/cmd/go/internal/modget/get.go
+++ b/vendor/cmd/go/internal/modget/get.go
@@ -229,7 +229,7 @@
 	// and a list of install targets (for the "go install" at the end).
 	var tasks []*task
 	var install []string
-	for _, arg := range search.CleanImportPaths(args) {
+	for _, arg := range search.CleanPatterns(args) {
 		// Argument is module query path@vers, or else path with implicit @latest.
 		path := arg
 		vers := ""
@@ -374,7 +374,7 @@
 	// Now we know the specific version of each path@vers.
 	// The final build list will be the union of three build lists:
 	//	1. the original build list
-	//	2. the modules named on the command line
+	//	2. the modules named on the command line (other than @none)
 	//	3. the upgraded requirements of those modules (if upgrading)
 	// Start building those lists.
 	// This loop collects (2).
@@ -395,7 +395,9 @@
 			continue // already added
 		}
 		byPath[t.m.Path] = t
-		named = append(named, t.m)
+		if t.m.Version != "none" {
+			named = append(named, t.m)
+		}
 	}
 	base.ExitIfErrors()
 
@@ -513,18 +515,34 @@
 	}
 
 	if len(install) > 0 {
+		// All requested versions were explicitly @none.
+		// Note that 'go get -u' without any arguments results in len(install) == 1:
+		// search.CleanImportPaths returns "." for empty args.
 		work.BuildInit()
-		var pkgs []string
-		for _, p := range load.PackagesAndErrors(install) {
-			if p.Error == nil || !strings.HasPrefix(p.Error.Err, "no Go files") {
-				pkgs = append(pkgs, p.ImportPath)
+		pkgs := load.PackagesAndErrors(install)
+		var todo []*load.Package
+		for _, p := range pkgs {
+			// Ignore "no Go source files" errors for 'go get' operations on modules.
+			if p.Error != nil {
+				if len(args) == 0 && getU != "" && strings.HasPrefix(p.Error.Err, "no Go files") {
+					// Upgrading modules: skip the implicitly-requested package at the
+					// current directory, even if it is not tho module root.
+					continue
+				}
+				if strings.Contains(p.Error.Err, "cannot find module providing") && modload.ModuleInfo(p.ImportPath) != nil {
+					// Explicitly-requested module, but it doesn't contain a package at the
+					// module root.
+					continue
+				}
 			}
+			todo = append(todo, p)
 		}
+
 		// If -d was specified, we're done after the download: no build.
 		// (The load.PackagesAndErrors is what did the download
 		// of the named packages and their dependencies.)
-		if len(pkgs) > 0 && !*getD {
-			work.InstallPackages(pkgs)
+		if len(todo) > 0 && !*getD {
+			work.InstallPackages(install, todo)
 		}
 	}
 }
@@ -534,13 +552,6 @@
 // If forceModulePath is set, getQuery must interpret path
 // as a module path.
 func getQuery(path, vers string, forceModulePath bool) (module.Version, error) {
-	if path == modload.Target.Path {
-		if vers != "" {
-			return module.Version{}, fmt.Errorf("cannot update main module to explicit version")
-		}
-		return modload.Target, nil
-	}
-
 	if vers == "" {
 		vers = "latest"
 	}
@@ -552,34 +563,14 @@
 		return module.Version{Path: path, Version: info.Version}, nil
 	}
 
-	// Even if the query fails, if the path is (or must be) a real module, then report the query error.
-	if forceModulePath || *getM || isModulePath(path) {
+	// Even if the query fails, if the path must be a real module, then report the query error.
+	if forceModulePath || *getM {
 		return module.Version{}, err
 	}
 
-	// Otherwise, interpret the package path as an import
-	// and determine what module that import would address
-	// if found in the current source code.
-	// Then apply the version to that module.
-	m, _, err := modload.Import(path)
-	if err != nil {
-		return module.Version{}, err
-	}
-	if m.Path == "" {
-		return module.Version{}, fmt.Errorf("package %q is not in a module", path)
-	}
-	info, err = modload.Query(m.Path, vers, modload.Allowed)
-	if err != nil {
-		return module.Version{}, err
-	}
-	return module.Version{Path: m.Path, Version: info.Version}, nil
-}
-
-// isModulePath reports whether path names an actual module,
-// defined as one with an accessible latest version.
-func isModulePath(path string) bool {
-	_, err := modload.Query(path, "latest", modload.Allowed)
-	return err == nil
+	// Otherwise, try a package path.
+	m, _, err := modload.QueryPackage(path, vers, modload.Allowed)
+	return m, err
 }
 
 // An upgrader adapts an underlying mvs.Reqs to apply an
diff --git a/vendor/cmd/go/internal/modload/build.go b/vendor/cmd/go/internal/modload/build.go
index b989af2..cebb802 100644
--- a/vendor/cmd/go/internal/modload/build.go
+++ b/vendor/cmd/go/internal/modload/build.go
@@ -25,15 +25,21 @@
 )
 
 func isStandardImportPath(path string) bool {
+	return findStandardImportPath(path) != ""
+}
+
+func findStandardImportPath(path string) string {
 	if search.IsStandardImportPath(path) {
-		if _, err := os.Stat(filepath.Join(cfg.GOROOT, "src", path)); err == nil {
-			return true
+		dir := filepath.Join(cfg.GOROOT, "src", path)
+		if _, err := os.Stat(dir); err == nil {
+			return dir
 		}
-		if _, err := os.Stat(filepath.Join(cfg.GOROOT, "src/vendor", path)); err == nil {
-			return true
+		dir = filepath.Join(cfg.GOROOT, "src/vendor", path)
+		if _, err := os.Stat(dir); err == nil {
+			return dir
 		}
 	}
-	return false
+	return ""
 }
 
 func PackageModuleInfo(pkgpath string) *modinfo.ModulePublic {
@@ -144,23 +150,25 @@
 
 	complete(info)
 
-	if r := Replacement(m); r.Path != "" {
-		info.Replace = &modinfo.ModulePublic{
-			Path:      r.Path,
-			Version:   r.Version,
-			GoVersion: info.GoVersion,
-		}
-		if r.Version == "" {
-			if filepath.IsAbs(r.Path) {
-				info.Replace.Dir = r.Path
-			} else {
-				info.Replace.Dir = filepath.Join(ModRoot, r.Path)
+	if fromBuildList {
+		if r := Replacement(m); r.Path != "" {
+			info.Replace = &modinfo.ModulePublic{
+				Path:      r.Path,
+				Version:   r.Version,
+				GoVersion: info.GoVersion,
 			}
+			if r.Version == "" {
+				if filepath.IsAbs(r.Path) {
+					info.Replace.Dir = r.Path
+				} else {
+					info.Replace.Dir = filepath.Join(ModRoot, r.Path)
+				}
+			}
+			complete(info.Replace)
+			info.Dir = info.Replace.Dir
+			info.GoMod = filepath.Join(info.Dir, "go.mod")
+			info.Error = nil // ignore error loading original module version (it has been replaced)
 		}
-		complete(info.Replace)
-		info.Dir = info.Replace.Dir
-		info.GoMod = filepath.Join(info.Dir, "go.mod")
-		info.Error = nil // ignore error loading original module version (it has been replaced)
 	}
 
 	return info
diff --git a/vendor/cmd/go/internal/modload/help.go b/vendor/cmd/go/internal/modload/help.go
index 64c70b7..f2f3419 100644
--- a/vendor/cmd/go/internal/modload/help.go
+++ b/vendor/cmd/go/internal/modload/help.go
@@ -6,8 +6,7 @@
 
 import "cmd/go/internal/base"
 
-// TODO(rsc): The links out to research.swtch.com here should all be
-// replaced eventually with links to proper documentation.
+// TODO(rsc): The "module code layout" section needs to be written.
 
 var HelpModules = &base.Command{
 	UsageLine: "modules",
@@ -81,7 +80,7 @@
 The go.mod file can also specify replacements and excluded versions
 that only apply when building the module directly; they are ignored
 when the module is incorporated into a larger build.
-For more about the go.mod file, see https://research.swtch.com/vgo-module.
+For more about the go.mod file, see 'go help go.mod'.
 
 To start a new module, simply create a go.mod file in the root of the
 module's directory tree, containing only a module statement.
@@ -336,8 +335,6 @@
 about how source code in version control systems is mapped to
 module file trees.
 
-TODO: Add documentation to go command.
-
 Module downloading and verification
 
 The go command maintains, in the main module's root directory alongside
@@ -381,3 +378,85 @@
 are still ignored.
 	`,
 }
+
+var HelpGoMod = &base.Command{
+	UsageLine: "go.mod",
+	Short:     "the go.mod file",
+	Long: `
+A module version is defined by a tree of source files, with a go.mod
+file in its root. When the go command is run, it looks in the current
+directory and then successive parent directories to find the go.mod
+marking the root of the main (current) module.
+
+The go.mod file itself is line-oriented, with // comments but
+no /* */ comments. Each line holds a single directive, made up of a
+verb followed by arguments. For example:
+
+	module my/thing
+	require other/thing v1.0.2
+	require new/thing v2.3.4
+	exclude old/thing v1.2.3
+	replace bad/thing v1.4.5 => good/thing v1.4.5
+
+The verbs are module, to define the module path; require, to require
+a particular module at a given version or later; exclude, to exclude
+a particular module version from use; and replace, to replace a module
+version with a different module version. Exclude and replace apply only
+in the main module's go.mod and are ignored in dependencies.
+See https://research.swtch.com/vgo-mvs for details.
+
+The leading verb can be factored out of adjacent lines to create a block,
+like in Go imports:
+
+	require (
+		new/thing v2.3.4
+		old/thing v1.2.3
+	)
+
+The go.mod file is designed both to be edited directly and to be
+easily updated by tools. The 'go mod edit' command can be used to
+parse and edit the go.mod file from programs and tools.
+See 'go help mod edit'.
+
+The go command automatically updates go.mod each time it uses the
+module graph, to make sure go.mod always accurately reflects reality
+and is properly formatted. For example, consider this go.mod file:
+
+        module M
+
+        require (
+                A v1
+                B v1.0.0
+                C v1.0.0
+                D v1.2.3
+                E dev
+        )
+
+        exclude D v1.2.3
+
+The update rewrites non-canonical version identifiers to semver form,
+so A's v1 becomes v1.0.0 and E's dev becomes the pseudo-version for the
+latest commit on the dev branch, perhaps v0.0.0-20180523231146-b3f5c0f6e5f1.
+
+The update modifies requirements to respect exclusions, so the
+requirement on the excluded D v1.2.3 is updated to use the next
+available version of D, perhaps D v1.2.4 or D v1.3.0.
+
+The update removes redundant or misleading requirements.
+For example, if A v1.0.0 itself requires B v1.2.0 and C v1.0.0,
+then go.mod's requirement of B v1.0.0 is misleading (superseded by
+A's need for v1.2.0), and its requirement of C v1.0.0 is redundant
+(implied by A's need for the same version), so both will be removed.
+If module M contains packages that directly import packages from B or
+C, then the requirements will be kept but updated to the actual
+versions being used.
+
+Finally, the update reformats the go.mod in a canonical formatting, so
+that future mechanical changes will result in minimal diffs.
+
+Because the module graph defines the meaning of import statements, any
+commands that load packages also use and therefore update go.mod,
+including go build, go get, go install, go list, go test, go mod graph,
+go mod tidy, and go mod why.
+	`,
+}
diff --git a/vendor/cmd/go/internal/modload/import.go b/vendor/cmd/go/internal/modload/import.go
index f0e7d86..12d9407 100644
--- a/vendor/cmd/go/internal/modload/import.go
+++ b/vendor/cmd/go/internal/modload/import.go
@@ -10,11 +10,11 @@
 	"fmt"
 	"go/build"
 	"os"
-	pathpkg "path"
 	"path/filepath"
 	"strings"
 
 	"cmd/go/internal/cfg"
+	"cmd/go/internal/modfetch/codehost"
 	"cmd/go/internal/module"
 	"cmd/go/internal/par"
 	"cmd/go/internal/search"
@@ -42,7 +42,7 @@
 // If the package cannot be found in the current build list,
 // Import returns an ImportMissingError as the error.
 // If Import can identify a module that could be added to supply the package,
-// the ImportMissingErr records that module.
+// the ImportMissingError records that module.
 func Import(path string) (m module.Version, dir string, err error) {
 	if strings.Contains(path, "@") {
 		return module.Version{}, "", fmt.Errorf("import path should not have @version")
@@ -124,24 +124,6 @@
 		return module.Version{}, "", errors.New(buf.String())
 	}
 
-	// Special case: if the path matches a module path,
-	// and we haven't found code in any module on the build list
-	// (since we haven't returned yet),
-	// force the use of the current module instead of
-	// looking for an alternate one.
-	// This helps "go get golang.org/x/net" even though
-	// there is no code in x/net.
-	for _, m := range buildList {
-		if m.Path == path {
-			root, isLocal, err := fetch(m)
-			if err != nil {
-				return module.Version{}, "", err
-			}
-			dir, _ := dirInModule(path, m.Path, root, isLocal)
-			return m, dir, nil
-		}
-	}
-
 	// Not on build list.
 
 	// Look up module containing the package, for addition to the build list.
@@ -150,43 +132,14 @@
 		return module.Version{}, "", fmt.Errorf("import lookup disabled by -mod=%s", cfg.BuildMod)
 	}
 
-	for p := path; p != "."; p = pathpkg.Dir(p) {
-		// We can't upgrade the main module.
-		// Note that this loop does consider upgrading other modules on the build list.
-		// If that's too aggressive we can skip all paths already on the build list,
-		// not just Target.Path, but for now let's try being aggressive.
-		if p == Target.Path {
-			// Can't move to a new version of main module.
-			continue
+	m, _, err = QueryPackage(path, "latest", Allowed)
+	if err != nil {
+		if _, ok := err.(*codehost.VCSError); ok {
+			return module.Version{}, "", err
 		}
-
-		info, err := Query(p, "latest", Allowed)
-		if err != nil {
-			continue
-		}
-		m := module.Version{Path: p, Version: info.Version}
-		root, isLocal, err := fetch(m)
-		if err != nil {
-			continue
-		}
-		_, ok := dirInModule(path, m.Path, root, isLocal)
-		if ok {
-			return module.Version{}, "", &ImportMissingError{ImportPath: path, Module: m}
-		}
-
-		// Special case matching the one above:
-		// if m.Path matches path, assume adding it to the build list
-		// will either add the right code or the right code doesn't exist.
-		if m.Path == path {
-			return module.Version{}, "", &ImportMissingError{ImportPath: path, Module: m}
-		}
+		return module.Version{}, "", &ImportMissingError{ImportPath: path}
 	}
-
-	// Did not resolve import to any module.
-	// TODO(rsc): It would be nice to return a specific error encountered
-	// during the loop above if possible, but it's not clear how to pick
-	// out the right one.
-	return module.Version{}, "", &ImportMissingError{ImportPath: path}
+	return m, "", &ImportMissingError{ImportPath: path, Module: m}
 }
 
 // maybeInModule reports whether, syntactically,
@@ -228,7 +181,7 @@
 	// So we only check local module trees
 	// (the main module, and any directory trees pointed at by replace directives).
 	if isLocal {
-		for d := dir; d != mdir && len(d) > len(mdir); d = filepath.Dir(d) {
+		for d := dir; d != mdir && len(d) > len(mdir); {
 			haveGoMod := haveGoModCache.Do(d, func() interface{} {
 				_, err := os.Stat(filepath.Join(d, "go.mod"))
 				return err == nil
@@ -237,6 +190,13 @@
 			if haveGoMod {
 				return "", false
 			}
+			parent := filepath.Dir(d)
+			if parent == d {
+				// Break the loop, as otherwise we'd loop
+				// forever if d=="." and mdir=="".
+				break
+			}
+			d = parent
 		}
 	}
 
diff --git a/vendor/cmd/go/internal/modload/import_test.go b/vendor/cmd/go/internal/modload/import_test.go
index 8e01dc5..3f4ddab 100644
--- a/vendor/cmd/go/internal/modload/import_test.go
+++ b/vendor/cmd/go/internal/modload/import_test.go
@@ -21,7 +21,7 @@
 	},
 	{
 		path: "golang.org/x/net",
-		err:  "missing module for import: golang.org/x/net@.* provides golang.org/x/net",
+		err:  "cannot find module providing package golang.org/x/net",
 	},
 	{
 		path: "golang.org/x/text",
diff --git a/vendor/cmd/go/internal/modload/init.go b/vendor/cmd/go/internal/modload/init.go
index 8ce0c32..f995bad 100644
--- a/vendor/cmd/go/internal/modload/init.go
+++ b/vendor/cmd/go/internal/modload/init.go
@@ -150,8 +150,20 @@
 		ModRoot = cwd
 	} else {
 		ModRoot, _ = FindModuleRoot(cwd, "", MustUseModules)
-		if ModRoot == "" && !MustUseModules {
-			return
+		if !MustUseModules {
+			if ModRoot == "" {
+				return
+			}
+			if search.InDir(ModRoot, os.TempDir()) == "." {
+				// If you create /tmp/go.mod for experimenting,
+				// then any tests that create work directories under /tmp
+				// will find it and get modules when they're not expecting them.
+				// It's a bit of a peculiar thing to disallow but quite mysterious
+				// when it happens. See golang.org/issue/26708.
+				ModRoot = ""
+				fmt.Fprintf(os.Stderr, "go: warning: ignoring go.mod in system temp root %v\n", os.TempDir())
+				return
+			}
 		}
 	}
 
@@ -163,6 +175,7 @@
 	load.ModPackageBuildInfo = PackageBuildInfo
 	load.ModInfoProg = ModInfoProg
 	load.ModImportFromFiles = ImportFromFiles
+	load.ModDirImportPath = DirImportPath
 
 	search.SetModRoot(ModRoot)
 }
@@ -521,7 +534,10 @@
 
 // WriteGoMod writes the current build list back to go.mod.
 func WriteGoMod() {
-	if !allowWriteGoMod {
+	// If we're using -mod=vendor we basically ignored
+	// go.mod, so definitely don't try to write back our
+	// incomplete view of the world.
+	if !allowWriteGoMod || cfg.BuildMod == "vendor" {
 		return
 	}
 
diff --git a/vendor/cmd/go/internal/modload/load.go b/vendor/cmd/go/internal/modload/load.go
index 9c55044..e6340b8 100644
--- a/vendor/cmd/go/internal/modload/load.go
+++ b/vendor/cmd/go/internal/modload/load.go
@@ -27,6 +27,7 @@
 	"cmd/go/internal/par"
 	"cmd/go/internal/search"
 	"cmd/go/internal/semver"
+	"cmd/go/internal/str"
 )
 
 // buildList is the list of modules to use for building packages.
@@ -50,24 +51,46 @@
 
 // ImportPaths returns the set of packages matching the args (patterns),
 // adding modules to the build list as needed to satisfy new imports.
-func ImportPaths(args []string) []string {
+func ImportPaths(patterns []string) []*search.Match {
 	InitMod()
 
-	cleaned := search.CleanImportPaths(args)
+	var matches []*search.Match
+	for _, pattern := range search.CleanPatterns(patterns) {
+		m := &search.Match{
+			Pattern: pattern,
+			Literal: !strings.Contains(pattern, "...") && !search.IsMetaPackage(pattern),
+		}
+		if m.Literal {
+			m.Pkgs = []string{pattern}
+		}
+		matches = append(matches, m)
+	}
+
+	fsDirs := make([][]string, len(matches))
 	loaded = newLoader()
-	var paths []string
-	loaded.load(func() []string {
-		var roots []string
-		paths = nil
-		for _, pkg := range cleaned {
+	updateMatches := func(iterating bool) {
+		for i, m := range matches {
 			switch {
-			case build.IsLocalImport(pkg) || filepath.IsAbs(pkg):
-				list := []string{pkg}
-				if strings.Contains(pkg, "...") {
-					// TODO: Where is the go.mod cutoff?
-					list = warnPattern(pkg, search.AllPackagesInFS(pkg))
+			case build.IsLocalImport(m.Pattern) || filepath.IsAbs(m.Pattern):
+				// Evaluate list of file system directories on first iteration.
+				if fsDirs[i] == nil {
+					var dirs []string
+					if m.Literal {
+						dirs = []string{m.Pattern}
+					} else {
+						dirs = search.MatchPackagesInFS(m.Pattern).Pkgs
+					}
+					fsDirs[i] = dirs
 				}
-				for _, pkg := range list {
+
+				// Make a copy of the directory list and translate to import paths.
+				// Note that whether a directory corresponds to an import path
+				// changes as the build list is updated, and a directory can change
+				// from not being in the build list to being in it and back as
+				// the exact version of a particular module increases during
+				// the loader iterations.
+				m.Pkgs = str.StringList(fsDirs[i])
+				for i, pkg := range m.Pkgs {
 					dir := pkg
 					if !filepath.IsAbs(dir) {
 						dir = filepath.Join(cwd, pkg)
@@ -93,40 +116,67 @@
 					} else if path := pathInModuleCache(dir); path != "" {
 						pkg = path
 					} else {
-						base.Errorf("go: directory %s outside available modules", base.ShortPath(dir))
-						continue
+						pkg = ""
+						if !iterating {
+							base.Errorf("go: directory %s outside available modules", base.ShortPath(dir))
+						}
 					}
+					info, err := os.Stat(dir)
+					if err != nil || !info.IsDir() {
+						// If the directory does not exist,
+						// don't turn it into an import path
+						// that will trigger a lookup.
+						pkg = ""
+						if !iterating {
+							if err != nil {
+								base.Errorf("go: no such directory %v", m.Pattern)
+							} else {
+								base.Errorf("go: %s is not a directory", m.Pattern)
+							}
+						}
+					}
+					m.Pkgs[i] = pkg
+				}
+
+			case strings.Contains(m.Pattern, "..."):
+				m.Pkgs = matchPackages(m.Pattern, loaded.tags, true, buildList)
+
+			case m.Pattern == "all":
+				loaded.testAll = true
+				if iterating {
+					// Enumerate the packages in the main module.
+					// We'll load the dependencies as we find them.
+					m.Pkgs = matchPackages("...", loaded.tags, false, []module.Version{Target})
+				} else {
+					// Starting with the packages in the main module,
+					// enumerate the full list of "all".
+					m.Pkgs = loaded.computePatternAll(m.Pkgs)
+				}
+
+			case search.IsMetaPackage(m.Pattern): // std, cmd
+				if len(m.Pkgs) == 0 {
+					m.Pkgs = search.MatchPackages(m.Pattern).Pkgs
+				}
+			}
+		}
+	}
+
+	loaded.load(func() []string {
+		var roots []string
+		updateMatches(true)
+		for _, m := range matches {
+			for _, pkg := range m.Pkgs {
+				if pkg != "" {
 					roots = append(roots, pkg)
-					paths = append(paths, pkg)
 				}
-
-			case pkg == "all":
-				if loaded.testRoots {
-					loaded.testAll = true
-				}
-				// TODO: Don't print warnings multiple times.
-				roots = append(roots, warnPattern("all", matchPackages("...", loaded.tags, []module.Version{Target}))...)
-				paths = append(paths, "all") // will expand after load completes
-
-			case search.IsMetaPackage(pkg): // std, cmd
-				list := search.AllPackages(pkg)
-				roots = append(roots, list...)
-				paths = append(paths, list...)
-
-			case strings.Contains(pkg, "..."):
-				// TODO: Don't we need to reevaluate this one last time once the build list stops changing?
-				list := warnPattern(pkg, matchPackages(pkg, loaded.tags, buildList))
-				roots = append(roots, list...)
-				paths = append(paths, list...)
-
-			default:
-				roots = append(roots, pkg)
-				paths = append(paths, pkg)
 			}
 		}
 		return roots
 	})
 
+	// One last pass to finalize wildcards.
+	updateMatches(false)
+
 	// A given module path may be used as itself or as a replacement for another
 	// module, but not both at the same time. Otherwise, the aliasing behavior is
 	// too subtle (see https://golang.org/issue/26607), and we don't want to
@@ -140,34 +190,14 @@
 		if prev, ok := firstPath[src]; !ok {
 			firstPath[src] = mod.Path
 		} else if prev != mod.Path {
-			base.Errorf("go: %s@%s used for two different module paths (%s and %s)", mod.Path, mod.Version, prev, mod.Path)
+			base.Errorf("go: %s@%s used for two different module paths (%s and %s)", src.Path, src.Version, prev, mod.Path)
 		}
 	}
 	base.ExitIfErrors()
-
 	WriteGoMod()
 
-	// Process paths to produce final paths list.
-	// Remove duplicates and expand "all".
-	have := make(map[string]bool)
-	var final []string
-	for _, path := range paths {
-		if have[path] {
-			continue
-		}
-		have[path] = true
-		if path == "all" {
-			for _, pkg := range loaded.pkgs {
-				if !have[pkg.path] {
-					have[pkg.path] = true
-					final = append(final, pkg.path)
-				}
-			}
-			continue
-		}
-		final = append(final, path)
-	}
-	return final
+	search.WarnUnmatched(matches)
+	return matches
 }
 
 // pathInModuleCache returns the import path of the directory dir,
@@ -218,6 +248,28 @@
 	WriteGoMod()
 }
 
+// DirImportPath returns the effective import path for dir,
+// provided it is within the main module, or else returns ".".
+func DirImportPath(dir string) string {
+	if !filepath.IsAbs(dir) {
+		dir = filepath.Join(cwd, dir)
+	} else {
+		dir = filepath.Clean(dir)
+	}
+
+	if dir == ModRoot {
+		return Target.Path
+	}
+	if strings.HasPrefix(dir, ModRoot+string(filepath.Separator)) {
+		suffix := filepath.ToSlash(dir[len(ModRoot):])
+		if strings.HasPrefix(suffix, "/vendor/") {
+			return strings.TrimPrefix(suffix, "/vendor/")
+		}
+		return Target.Path + suffix
+	}
+	return "."
+}
+
 // LoadBuildList loads and returns the build list from go.mod.
 // The loading of the build list happens automatically in ImportPaths:
 // LoadBuildList need only be called if ImportPaths is not
@@ -270,6 +322,9 @@
 
 	var paths []string
 	for _, pkg := range loaded.pkgs {
+		if e, ok := pkg.err.(*ImportMissingError); ok && e.Module.Path == "" {
+			continue // Package doesn't actually exist.
+		}
 		paths = append(paths, pkg.path)
 	}
 	return paths
@@ -282,7 +337,7 @@
 // TargetPackages returns the list of packages in the target (top-level) module,
 // under all build tag settings.
 func TargetPackages() []string {
-	return matchPackages("...", anyTags, []module.Version{Target})
+	return matchPackages("...", anyTags, false, []module.Version{Target})
 }
 
 // BuildList returns the module build list,
@@ -337,19 +392,28 @@
 	return loaded.direct[path]
 }
 
-// Lookup XXX TODO.
-func Lookup(parentPath, path string) (dir, realPath string, err error) {
-	realPath = ImportMap(path)
-	if realPath == "" {
-		if isStandardImportPath(path) {
-			dir := filepath.Join(cfg.GOROOT, "src", path)
-			if _, err := os.Stat(dir); err == nil {
-				return dir, path, nil
-			}
+// Lookup returns the source directory, import path, and any loading error for
+// the package at path.
+// Lookup requires that one of the Load functions in this package has already
+// been called.
+func Lookup(path string) (dir, realPath string, err error) {
+	pkg, ok := loaded.pkgCache.Get(path).(*loadPkg)
+	if !ok {
+		// The loader should have found all the relevant paths.
+		// There are a few exceptions, though:
+		//	- during go list without -test, the p.Resolve calls to process p.TestImports and p.XTestImports
+		//	  end up here to canonicalize the import paths.
+		//	- during any load, non-loaded packages like "unsafe" end up here.
+		//	- during any load, build-injected dependencies like "runtime/cgo" end up here.
+		//	- because we ignore appengine/* in the module loader,
+		//	  the dependencies of any actual appengine/* library end up here.
+		dir := findStandardImportPath(path)
+		if dir != "" {
+			return dir, path, nil
 		}
-		return "", "", fmt.Errorf("no such package in module")
+		return "", "", errMissing
 	}
-	return PackageDir(realPath), realPath, nil
+	return pkg.dir, pkg.path, pkg.err
 }
 
 // A loader manages the process of loading information about
@@ -382,14 +446,13 @@
 	goVersion map[string]string // go version recorded in each module
 }
 
+// LoadTests controls whether the loaders load tests of the root packages.
+var LoadTests bool
+
 func newLoader() *loader {
 	ld := new(loader)
 	ld.tags = imports.Tags()
-
-	switch cfg.CmdName {
-	case "test", "vet":
-		ld.testRoots = true
-	}
+	ld.testRoots = LoadTests
 	return ld
 }
 
@@ -457,9 +520,7 @@
 				}
 				continue
 			}
-			if pkg.err != nil {
-				base.Errorf("go: %s: %s", pkg.stackText(), pkg.err)
-			}
+			// Leave other errors for Import or load.Packages to report.
 		}
 		base.ExitIfErrors()
 		if numAdded == 0 {
@@ -504,9 +565,6 @@
 			}
 		}
 	}
-
-	// Check for visibility violations.
-	// TODO!
 }
 
 // pkg returns the *loadPkg for path, creating and queuing it if needed.
@@ -561,11 +619,6 @@
 		var err error
 		imports, testImports, err = scanDir(pkg.dir, ld.tags)
 		if err != nil {
-			if strings.HasPrefix(err.Error(), "no Go ") {
-				// Don't print about directories with no Go source files.
-				// Let the eventual real package load do that.
-				return
-			}
 			pkg.err = err
 			return
 		}
@@ -585,6 +638,35 @@
 	}
 }
 
+// computePatternAll returns the list of packages matching pattern "all",
+// starting with a list of the import paths for the packages in the main module.
+func (ld *loader) computePatternAll(paths []string) []string {
+	seen := make(map[*loadPkg]bool)
+	var all []string
+	var walk func(*loadPkg)
+	walk = func(pkg *loadPkg) {
+		if seen[pkg] {
+			return
+		}
+		seen[pkg] = true
+		if pkg.testOf == nil {
+			all = append(all, pkg.path)
+		}
+		for _, p := range pkg.imports {
+			walk(p)
+		}
+		if p := pkg.test; p != nil {
+			walk(p)
+		}
+	}
+	for _, path := range paths {
+		walk(ld.pkg(path, false))
+	}
+	sort.Strings(all)
+
+	return all
+}
+
 // scanDir is like imports.ScanDir but elides known magic imports from the list,
 // so that we do not go looking for packages that don't really exist.
 //
@@ -675,6 +757,51 @@
 	return buf.String()
 }
 
+// why returns the text to use in "go mod why" output about the given package.
+// It is less ornate than the stackText but conatins the same information.
+func (pkg *loadPkg) why() string {
+	var buf strings.Builder
+	var stack []*loadPkg
+	for p := pkg; p != nil; p = p.stack {
+		stack = append(stack, p)
+	}
+
+	for i := len(stack) - 1; i >= 0; i-- {
+		p := stack[i]
+		if p.testOf != nil {
+			fmt.Fprintf(&buf, "%s.test\n", p.testOf.path)
+		} else {
+			fmt.Fprintf(&buf, "%s\n", p.path)
+		}
+	}
+	return buf.String()
+}
+
+// Why returns the "go mod why" output stanza for the given package,
+// without the leading # comment.
+// The package graph must have been loaded already, usually by LoadALL.
+// If there is no reason for the package to be in the current build,
+// Why returns an empty string.
+func Why(path string) string {
+	pkg, ok := loaded.pkgCache.Get(path).(*loadPkg)
+	if !ok {
+		return ""
+	}
+	return pkg.why()
+}
+
+// WhyDepth returns the number of steps in the Why listing.
+// If there is no reason for the package to be in the current build,
+// WhyDepth returns 0.
+func WhyDepth(path string) int {
+	n := 0
+	pkg, _ := loaded.pkgCache.Get(path).(*loadPkg)
+	for p := pkg; p != nil; p = p.stack {
+		n++
+	}
+	return n
+}
+
 // Replacement returns the replacement for mod, if any, from go.mod.
 // If there is no replacement for mod, Replacement returns
 // a module.Version with Path == "".
diff --git a/vendor/cmd/go/internal/modload/query.go b/vendor/cmd/go/internal/modload/query.go
index c69e49a..3b550f1 100644
--- a/vendor/cmd/go/internal/modload/query.go
+++ b/vendor/cmd/go/internal/modload/query.go
@@ -6,9 +6,11 @@
 
 import (
 	"cmd/go/internal/modfetch"
+	"cmd/go/internal/modfetch/codehost"
 	"cmd/go/internal/module"
 	"cmd/go/internal/semver"
 	"fmt"
+	pathpkg "path"
 	"strings"
 )
 
@@ -29,6 +31,8 @@
 //
 // If the allowed function is non-nil, Query excludes any versions for which allowed returns false.
 //
+// If path is the path of the main module and the query is "latest",
+// Query returns Target.Version as the version.
 func Query(path, query string, allowed func(module.Version) bool) (*modfetch.RevInfo, error) {
 	if allowed == nil {
 		allowed = func(module.Version) bool { return true }
@@ -117,6 +121,16 @@
 		return info, nil
 	}
 
+	if path == Target.Path {
+		if query != "latest" {
+			return nil, fmt.Errorf("can't query specific version (%q) for the main module (%s)", query, path)
+		}
+		if !allowed(Target) {
+			return nil, fmt.Errorf("internal error: main module version is not allowed")
+		}
+		return &modfetch.RevInfo{Version: Target.Version}, nil
+	}
+
 	// Load versions and execute query.
 	repo, err := modfetch.Lookup(path)
 	if err != nil {
@@ -187,3 +201,49 @@
 func matchSemverPrefix(p, v string) bool {
 	return len(v) > len(p) && v[len(p)] == '.' && v[:len(p)] == p
 }
+
+// QueryPackage looks up a revision of a module containing path.
+//
+// If multiple modules with revisions matching the query provide the requested
+// package, QueryPackage picks the one with the longest module path.
+//
+// If the path is in the the main module and the query is "latest",
+// QueryPackage returns Target as the version.
+func QueryPackage(path, query string, allowed func(module.Version) bool) (module.Version, *modfetch.RevInfo, error) {
+	if _, ok := dirInModule(path, Target.Path, ModRoot, true); ok {
+		if query != "latest" {
+			return module.Version{}, nil, fmt.Errorf("can't query specific version (%q) for package %s in the main module (%s)", query, path, Target.Path)
+		}
+		if !allowed(Target) {
+			return module.Version{}, nil, fmt.Errorf("internal error: package %s is in the main module (%s), but version is not allowed", path, Target.Path)
+		}
+		return Target, &modfetch.RevInfo{Version: Target.Version}, nil
+	}
+
+	finalErr := errMissing
+	for p := path; p != "."; p = pathpkg.Dir(p) {
+		info, err := Query(p, query, allowed)
+		if err != nil {
+			if _, ok := err.(*codehost.VCSError); ok {
+				// A VCSError means we know where to find the code,
+				// we just can't. Abort search.
+				return module.Version{}, nil, err
+			}
+			if finalErr == errMissing {
+				finalErr = err
+			}
+			continue
+		}
+		m := module.Version{Path: p, Version: info.Version}
+		root, isLocal, err := fetch(m)
+		if err != nil {
+			return module.Version{}, nil, err
+		}
+		_, ok := dirInModule(path, m.Path, root, isLocal)
+		if ok {
+			return m, info, nil
+		}
+	}
+
+	return module.Version{}, nil, finalErr
+}
diff --git a/vendor/cmd/go/internal/modload/search.go b/vendor/cmd/go/internal/modload/search.go
index 9ce65f0..24825cc 100644
--- a/vendor/cmd/go/internal/modload/search.go
+++ b/vendor/cmd/go/internal/modload/search.go
@@ -19,7 +19,7 @@
 
 // matchPackages returns a list of packages in the list of modules
 // matching the pattern. Package loading assumes the given set of tags.
-func matchPackages(pattern string, tags map[string]bool, modules []module.Version) []string {
+func matchPackages(pattern string, tags map[string]bool, useStd bool, modules []module.Version) []string {
 	match := func(string) bool { return true }
 	treeCanMatch := func(string) bool { return true }
 	if !search.IsMetaPackage(pattern) {
@@ -35,28 +35,30 @@
 	}
 	var pkgs []string
 
-	for _, mod := range modules {
-		if !treeCanMatch(mod.Path) {
-			continue
-		}
-		var root string
-		if mod.Version == "" {
-			root = ModRoot
-		} else {
-			var err error
-			root, _, err = fetch(mod)
-			if err != nil {
-				base.Errorf("go: %v", err)
-				continue
-			}
-		}
+	walkPkgs := func(root, importPathRoot string) {
 		root = filepath.Clean(root)
-
+		var cmd string
+		if root == cfg.GOROOTsrc {
+			cmd = filepath.Join(root, "cmd")
+		}
 		filepath.Walk(root, func(path string, fi os.FileInfo, err error) error {
 			if err != nil {
 				return nil
 			}
 
+			// Don't use GOROOT/src but do walk down into it.
+			if path == root && importPathRoot == "" {
+				return nil
+			}
+
+			// GOROOT/src/cmd makes use of GOROOT/src/cmd/vendor,
+			// which module mode can't deal with. Eventually we'll stop using
+			// that vendor directory, and then we can remove this exclusion.
+			// golang.org/issue/26924.
+			if path == cmd {
+				return filepath.SkipDir
+			}
+
 			want := true
 			// Avoid .foo, _foo, and testdata directory trees.
 			_, elem := filepath.Split(path)
@@ -64,7 +66,10 @@
 				want = false
 			}
 
-			name := mod.Path + filepath.ToSlash(path[len(root):])
+			name := importPathRoot + filepath.ToSlash(path[len(root):])
+			if importPathRoot == "" {
+				name = name[1:] // cut leading slash
+			}
 			if !treeCanMatch(name) {
 				want = false
 			}
@@ -102,5 +107,28 @@
 			return nil
 		})
 	}
+
+	if useStd {
+		walkPkgs(cfg.GOROOTsrc, "")
+	}
+
+	for _, mod := range modules {
+		if !treeCanMatch(mod.Path) {
+			continue
+		}
+		var root string
+		if mod.Version == "" {
+			root = ModRoot
+		} else {
+			var err error
+			root, _, err = fetch(mod)
+			if err != nil {
+				base.Errorf("go: %v", err)
+				continue
+			}
+		}
+		walkPkgs(root, mod.Path)
+	}
+
 	return pkgs
 }
diff --git a/vendor/cmd/go/internal/module/module.go b/vendor/cmd/go/internal/module/module.go
index 03b4011..1dbb0f5 100644
--- a/vendor/cmd/go/internal/module/module.go
+++ b/vendor/cmd/go/internal/module/module.go
@@ -143,7 +143,7 @@
 		}
 	}
 	if _, _, ok := SplitPathVersion(path); !ok {
-		return fmt.Errorf("malformed module path %q: invalid version %s", path, path[strings.LastIndex(path, "/")+1:])
+		return fmt.Errorf("malformed module path %q: invalid version", path)
 	}
 	return nil
 }
@@ -300,6 +300,9 @@
 		return path, "", false
 	}
 	i := len(path)
+	if strings.HasSuffix(path, "-unstable") {
+		i -= len("-unstable")
+	}
 	for i > 0 && ('0' <= path[i-1] && path[i-1] <= '9') {
 		i--
 	}
@@ -317,6 +320,9 @@
 // MatchPathMajor reports whether the semantic version v
 // matches the path major version pathMajor.
 func MatchPathMajor(v, pathMajor string) bool {
+	if strings.HasPrefix(pathMajor, ".v") && strings.HasSuffix(pathMajor, "-unstable") {
+		pathMajor = strings.TrimSuffix(pathMajor, "-unstable")
+	}
 	if strings.HasPrefix(v, "v0.0.0-") && pathMajor == ".v1" {
 		// Allow old bug in pseudo-versions that generated v0.0.0- pseudoversion for gopkg .v1.
 		// For example, gopkg.in/yaml.v2@v2.2.1's go.mod requires gopkg.in/check.v1 v0.0.0-20161208181325-20d25e280405.
diff --git a/vendor/cmd/go/internal/search/search.go b/vendor/cmd/go/internal/search/search.go
index b020f60..60ae736 100644
--- a/vendor/cmd/go/internal/search/search.go
+++ b/vendor/cmd/go/internal/search/search.go
@@ -17,32 +17,22 @@
 	"strings"
 )
 
-// AllPackages returns all the packages that can be found
+// A Match represents the result of matching a single package pattern.
+type Match struct {
+	Pattern string   // the pattern itself
+	Literal bool     // whether it is a literal (no wildcards)
+	Pkgs    []string // matching packages (dirs or import paths)
+}
+
+// MatchPackages returns all the packages that can be found
 // under the $GOPATH directories and $GOROOT matching pattern.
 // The pattern is either "all" (all packages), "std" (standard packages),
 // "cmd" (standard commands), or a path including "...".
-func AllPackages(pattern string) []string {
-	pkgs := MatchPackages(pattern)
-	if len(pkgs) == 0 {
-		fmt.Fprintf(os.Stderr, "warning: %q matched no packages\n", pattern)
+func MatchPackages(pattern string) *Match {
+	m := &Match{
+		Pattern: pattern,
+		Literal: false,
 	}
-	return pkgs
-}
-
-// AllPackagesInFS is like allPackages but is passed a pattern
-// beginning ./ or ../, meaning it should scan the tree rooted
-// at the given directory. There are ... in the pattern too.
-func AllPackagesInFS(pattern string) []string {
-	pkgs := MatchPackagesInFS(pattern)
-	if len(pkgs) == 0 {
-		fmt.Fprintf(os.Stderr, "warning: %q matched no packages\n", pattern)
-	}
-	return pkgs
-}
-
-// MatchPackages returns a list of package paths matching pattern
-// (see go help packages for pattern syntax).
-func MatchPackages(pattern string) []string {
 	match := func(string) bool { return true }
 	treeCanMatch := func(string) bool { return true }
 	if !IsMetaPackage(pattern) {
@@ -56,7 +46,6 @@
 	if !cfg.BuildContext.CgoEnabled {
 		have["runtime/cgo"] = true // ignore during walk
 	}
-	var pkgs []string
 
 	for _, src := range cfg.BuildContext.SrcDirs() {
 		if (pattern == "std" || pattern == "cmd") && src != cfg.GOROOTsrc {
@@ -123,11 +112,11 @@
 				return nil
 			}
 
-			pkgs = append(pkgs, name)
+			m.Pkgs = append(m.Pkgs, name)
 			return nil
 		})
 	}
-	return pkgs
+	return m
 }
 
 var modRoot string
@@ -136,10 +125,16 @@
 	modRoot = dir
 }
 
-// MatchPackagesInFS returns a list of package paths matching pattern,
-// which must begin with ./ or ../
-// (see go help packages for pattern syntax).
-func MatchPackagesInFS(pattern string) []string {
+// MatchPackagesInFS is like allPackages but is passed a pattern
+// beginning ./ or ../, meaning it should scan the tree rooted
+// at the given directory. There are ... in the pattern too.
+// (See go help packages for pattern syntax.)
+func MatchPackagesInFS(pattern string) *Match {
+	m := &Match{
+		Pattern: pattern,
+		Literal: false,
+	}
+
 	// Find directory to begin the scan.
 	// Could be smarter but this one optimization
 	// is enough for now, since ... is usually at the
@@ -168,7 +163,6 @@
 		}
 	}
 
-	var pkgs []string
 	filepath.Walk(dir, func(path string, fi os.FileInfo, err error) error {
 		if err != nil || !fi.IsDir() {
 			return nil
@@ -218,10 +212,10 @@
 			}
 			return nil
 		}
-		pkgs = append(pkgs, name)
+		m.Pkgs = append(m.Pkgs, name)
 		return nil
 	})
-	return pkgs
+	return m
 }
 
 // TreeCanMatchPattern(pattern)(name) reports whether
@@ -308,36 +302,53 @@
 	return strings.Join(elem, "/")
 }
 
-// ImportPaths returns the import paths to use for the given command line.
-func ImportPaths(args []string) []string {
-	args = CleanImportPaths(args)
-	var out []string
-	for _, a := range args {
+// WarnUnmatched warns about patterns that didn't match any packages.
+func WarnUnmatched(matches []*Match) {
+	for _, m := range matches {
+		if len(m.Pkgs) == 0 {
+			fmt.Fprintf(os.Stderr, "go: warning: %q matched no packages\n", m.Pattern)
+		}
+	}
+}
+
+// ImportPaths returns the matching paths to use for the given command line.
+// It calls ImportPathsQuiet and then WarnUnmatched.
+func ImportPaths(patterns []string) []*Match {
+	matches := ImportPathsQuiet(patterns)
+	WarnUnmatched(matches)
+	return matches
+}
+
+// ImportPathsQuiet is like ImportPaths but does not warn about patterns with no matches.
+func ImportPathsQuiet(patterns []string) []*Match {
+	var out []*Match
+	for _, a := range CleanPatterns(patterns) {
 		if IsMetaPackage(a) {
-			out = append(out, AllPackages(a)...)
+			out = append(out, MatchPackages(a))
 			continue
 		}
 		if strings.Contains(a, "...") {
 			if build.IsLocalImport(a) {
-				out = append(out, AllPackagesInFS(a)...)
+				out = append(out, MatchPackagesInFS(a))
 			} else {
-				out = append(out, AllPackages(a)...)
+				out = append(out, MatchPackages(a))
 			}
 			continue
 		}
-		out = append(out, a)
+		out = append(out, &Match{Pattern: a, Literal: true, Pkgs: []string{a}})
 	}
 	return out
 }
 
-// CleanImportPaths returns the import paths to use for the given
-// command line, but it does no wildcard expansion.
-func CleanImportPaths(args []string) []string {
-	if len(args) == 0 {
+// CleanPatterns returns the patterns to use for the given
+// command line. It canonicalizes the patterns but does not
+// evaluate any matches.
+func CleanPatterns(patterns []string) []string {
+	if len(patterns) == 0 {
 		return []string{"."}
 	}
 	var out []string
-	for _, a := range args {
+	for _, a := range patterns {
 		// Arguments are supposed to be import paths, but
 		// as a courtesy to Windows developers, rewrite \ to /
 		// in command-line arguments. Handles .\... and so on.
@@ -359,22 +370,6 @@
 	return out
 }
 
-// ImportPathsNoDotExpansion returns the import paths to use for the given
-// command line, but it does no ... expansion.
-// TODO(rsc): Delete once old go get is gone.
-func ImportPathsNoDotExpansion(args []string) []string {
-	args = CleanImportPaths(args)
-	var out []string
-	for _, a := range args {
-		if IsMetaPackage(a) {
-			out = append(out, AllPackages(a)...)
-			continue
-		}
-		out = append(out, a)
-	}
-	return out
-}
-
 // IsMetaPackage checks if name is a reserved package name that expands to multiple packages.
 func IsMetaPackage(name string) bool {
 	return name == "std" || name == "cmd" || name == "all"
diff --git a/vendor/cmd/go/internal/test/test.go b/vendor/cmd/go/internal/test/test.go
index d6fcc2a..3295e8f 100644
--- a/vendor/cmd/go/internal/test/test.go
+++ b/vendor/cmd/go/internal/test/test.go
@@ -27,6 +27,7 @@
 	"cmd/go/internal/cache"
 	"cmd/go/internal/cfg"
 	"cmd/go/internal/load"
+	"cmd/go/internal/modload"
 	"cmd/go/internal/str"
 	"cmd/go/internal/work"
 	"cmd/internal/test2json"
@@ -527,6 +528,8 @@
 }
 
 func runTest(cmd *base.Command, args []string) {
+	modload.LoadTests = true
+
 	pkgArgs, testArgs = testFlags(args)
 
 	work.FindExecCmd() // initialize cached result
diff --git a/vendor/cmd/go/internal/version/vgo.go b/vendor/cmd/go/internal/version/vgo.go
index bb7c709..89fba33 100644
--- a/vendor/cmd/go/internal/version/vgo.go
+++ b/vendor/cmd/go/internal/version/vgo.go
@@ -1,3 +1,3 @@
 package version
 
-const version = "devel +1b870077c8"
+const version = "devel +b0a1c5df98"
diff --git a/vendor/cmd/go/internal/vet/vet.go b/vendor/cmd/go/internal/vet/vet.go
index 11abb62..b64bf3f 100644
--- a/vendor/cmd/go/internal/vet/vet.go
+++ b/vendor/cmd/go/internal/vet/vet.go
@@ -8,6 +8,7 @@
 import (
 	"cmd/go/internal/base"
 	"cmd/go/internal/load"
+	"cmd/go/internal/modload"
 	"cmd/go/internal/work"
 	"path/filepath"
 )
@@ -35,6 +36,8 @@
 }
 
 func runVet(cmd *base.Command, args []string) {
+	modload.LoadTests = true
+
 	vetFlags, pkgArgs := vetFlags(args)
 
 	work.BuildInit()
diff --git a/vendor/cmd/go/internal/work/build.go b/vendor/cmd/go/internal/work/build.go
index c2524c4..d9e4ef1 100644
--- a/vendor/cmd/go/internal/work/build.go
+++ b/vendor/cmd/go/internal/work/build.go
@@ -434,7 +434,7 @@
 
 func runInstall(cmd *base.Command, args []string) {
 	BuildInit()
-	InstallPackages(args)
+	InstallPackages(args, load.PackagesForBuild(args))
 }
 
 // omitTestOnly returns pkgs with test-only packages removed.
@@ -454,12 +454,12 @@
 	return list
 }
 
-func InstallPackages(args []string) {
+func InstallPackages(patterns []string, pkgs []*load.Package) {
 	if cfg.GOBIN != "" && !filepath.IsAbs(cfg.GOBIN) {
 		base.Fatalf("cannot install, GOBIN must be an absolute path")
 	}
 
-	pkgs := omitTestOnly(pkgsFilter(load.PackagesForBuild(args)))
+	pkgs = omitTestOnly(pkgsFilter(pkgs))
 	for _, p := range pkgs {
 		if p.Target == "" {
 			switch {
@@ -520,7 +520,7 @@
 		// tools above did not apply, and a is just a simple Action
 		// with a list of Deps, one per package named in pkgs,
 		// the same as in runBuild.
-		a = b.buildmodeShared(ModeInstall, ModeInstall, args, pkgs, a)
+		a = b.buildmodeShared(ModeInstall, ModeInstall, patterns, pkgs, a)
 	}
 
 	b.Do(a)
@@ -535,7 +535,7 @@
 	// One way to view this behavior is that it is as if 'go install' first
 	// runs 'go build' and the moves the generated file to the install dir.
 	// See issue 9645.
-	if len(args) == 0 && len(pkgs) == 1 && pkgs[0].Name == "main" {
+	if len(patterns) == 0 && len(pkgs) == 1 && pkgs[0].Name == "main" {
 		// Compute file 'go build' would have created.
 		// If it exists and is an executable file, remove it.
 		_, targ := filepath.Split(pkgs[0].ImportPath)
diff --git a/vendor/cmd/go/internal/work/buildid.go b/vendor/cmd/go/internal/work/buildid.go
index 521b88c..4cad901 100644
--- a/vendor/cmd/go/internal/work/buildid.go
+++ b/vendor/cmd/go/internal/work/buildid.go
@@ -473,6 +473,14 @@
 				a.buildID = id[1] + buildIDSeparator + id[2]
 				linkID := hashToString(b.linkActionID(a.triggers[0]))
 				if id[0] == linkID {
+					// Best effort attempt to display output from the compile and link steps.
+					// If it doesn't work, it doesn't work: reusing the cached binary is more
+					// important than reprinting diagnostic information.
+					if c := cache.Default(); c != nil {
+						showStdout(b, c, a.actionID, "stdout")      // compile output
+						showStdout(b, c, a.actionID, "link-stdout") // link output
+					}
+
 					// Poison a.Target to catch uses later in the build.
 					a.Target = "DO NOT USE - main build pseudo-cache Target"
 					a.built = "DO NOT USE - main build pseudo-cache built"
@@ -490,6 +498,15 @@
 	// We avoid the nested build ID problem in the previous special case
 	// by recording the test results in the cache under the action ID half.
 	if !cfg.BuildA && len(a.triggers) == 1 && a.triggers[0].TryCache != nil && a.triggers[0].TryCache(b, a.triggers[0]) {
+		// Best effort attempt to display output from the compile and link steps.
+		// If it doesn't work, it doesn't work: reusing the test result is more
+		// important than reprinting diagnostic information.
+		if c := cache.Default(); c != nil {
+			showStdout(b, c, a.Deps[0].actionID, "stdout")      // compile output
+			showStdout(b, c, a.Deps[0].actionID, "link-stdout") // link output
+		}
+
+		// Poison a.Target to catch uses later in the build.
 		a.Target = "DO NOT USE -  pseudo-cache Target"
 		a.built = "DO NOT USE - pseudo-cache built"
 		return true
@@ -530,15 +547,7 @@
 		if !cfg.BuildA {
 			if file, _, err := c.GetFile(actionHash); err == nil {
 				if buildID, err := buildid.ReadFile(file); err == nil {
-					if stdout, stdoutEntry, err := c.GetBytes(cache.Subkey(a.actionID, "stdout")); err == nil {
-						if len(stdout) > 0 {
-							if cfg.BuildX || cfg.BuildN {
-								b.Showcmd("", "%s  # internal", joinUnambiguously(str.StringList("cat", c.OutputFile(stdoutEntry.OutputID))))
-							}
-							if !cfg.BuildN {
-								b.Print(string(stdout))
-							}
-						}
+					if err := showStdout(b, c, a.actionID, "stdout"); err == nil {
 						a.built = file
 						a.Target = "DO NOT USE - using cache"
 						a.buildID = buildID
@@ -559,6 +568,23 @@
 	return false
 }
 
+func showStdout(b *Builder, c *cache.Cache, actionID cache.ActionID, key string) error {
+	stdout, stdoutEntry, err := c.GetBytes(cache.Subkey(actionID, key))
+	if err != nil {
+		return err
+	}
+
+	if len(stdout) > 0 {
+		if cfg.BuildX || cfg.BuildN {
+			b.Showcmd("", "%s  # internal", joinUnambiguously(str.StringList("cat", c.OutputFile(stdoutEntry.OutputID))))
+		}
+		if !cfg.BuildN {
+			b.Print(string(stdout))
+		}
+	}
+	return nil
+}
+
 // flushOutput flushes the output being queued in a.
 func (b *Builder) flushOutput(a *Action) {
 	b.Print(string(a.output))
@@ -583,6 +609,26 @@
 		}
 	}
 
+	// Cache output from compile/link, even if we don't do the rest.
+	if c := cache.Default(); c != nil {
+		switch a.Mode {
+		case "build":
+			c.PutBytes(cache.Subkey(a.actionID, "stdout"), a.output)
+		case "link":
+			// Even though we don't cache the binary, cache the linker text output.
+			// We might notice that an installed binary is up-to-date but still
+			// want to pretend to have run the linker.
+			// Store it under the main package's action ID
+			// to make it easier to find when that's all we have.
+			for _, a1 := range a.Deps {
+				if p1 := a1.Package; p1 != nil && p1.Name == "main" {
+					c.PutBytes(cache.Subkey(a1.actionID, "link-stdout"), a.output)
+					break
+				}
+			}
+		}
+	}
+
 	// Find occurrences of old ID and compute new content-based ID.
 	r, err := os.Open(target)
 	if err != nil {
@@ -650,7 +696,6 @@
 				}
 				a.Package.Export = c.OutputFile(outputID)
 			}
-			c.PutBytes(cache.Subkey(a.actionID, "stdout"), a.output)
 		}
 	}
 
diff --git a/vendor/cmd/go/internal/work/exec.go b/vendor/cmd/go/internal/work/exec.go
index 19ed169..4f5b89a 100644
--- a/vendor/cmd/go/internal/work/exec.go
+++ b/vendor/cmd/go/internal/work/exec.go
@@ -1155,11 +1155,11 @@
 	// We still call updateBuildID to update a.buildID, which is important
 	// for test result caching, but passing rewrite=false (final arg)
 	// means we don't actually rewrite the binary, nor store the
-	// result into the cache.
-	// Not calling updateBuildID means we also don't insert these
-	// binaries into the build object cache. That's probably a net win:
+	// result into the cache. That's probably a net win:
 	// less cache space wasted on large binaries we are not likely to
 	// need again. (On the other hand it does make repeated go test slower.)
+	// It also makes repeated go run slower, which is a win in itself:
+	// we don't want people to treat go run like a scripting environment.
 	if err := b.updateBuildID(a, a.Target, !a.Package.Internal.OmitDebug); err != nil {
 		return err
 	}
diff --git a/vendor/cmd/go/main.go b/vendor/cmd/go/main.go
index 87997f8..0bf3a00 100644
--- a/vendor/cmd/go/main.go
+++ b/vendor/cmd/go/main.go
@@ -64,6 +64,7 @@
 		help.HelpCache,
 		help.HelpEnvironment,
 		help.HelpFileType,
+		modload.HelpGoMod,
 		help.HelpGopath,
 		get.HelpGopathGet,
 		modfetch.HelpGoproxy,
diff --git a/vendor/cmd/go/proxy_test.go b/vendor/cmd/go/proxy_test.go
index bd13513..a939f08 100644
--- a/vendor/cmd/go/proxy_test.go
+++ b/vendor/cmd/go/proxy_test.go
@@ -81,13 +81,13 @@
 		encPath := strings.Replace(name[:i], "_", "/", -1)
 		path, err := module.DecodePath(encPath)
 		if err != nil {
-			fmt.Fprintf(os.Stderr, "go proxy_test: %v", err)
+			fmt.Fprintf(os.Stderr, "go proxy_test: %v\n", err)
 			continue
 		}
 		encVers := name[i+1:]
 		vers, err := module.DecodeVersion(encVers)
 		if err != nil {
-			fmt.Fprintf(os.Stderr, "go proxy_test: %v", err)
+			fmt.Fprintf(os.Stderr, "go proxy_test: %v\n", err)
 			continue
 		}
 		modList = append(modList, module.Version{Path: path, Version: vers})
@@ -140,7 +140,7 @@
 	encVers, ext := file[:i], file[i+1:]
 	vers, err := module.DecodeVersion(encVers)
 	if err != nil {
-		fmt.Fprintf(os.Stderr, "go proxy_test: %v", err)
+		fmt.Fprintf(os.Stderr, "go proxy_test: %v\n", err)
 		http.NotFound(w, r)
 		return
 	}
diff --git a/vendor/cmd/go/testdata/mod/example.com_join_subpkg_v1.0.0.txt b/vendor/cmd/go/testdata/mod/example.com_join_subpkg_v1.0.0.txt
new file mode 100644
index 0000000..1ecfa0b
--- /dev/null
+++ b/vendor/cmd/go/testdata/mod/example.com_join_subpkg_v1.0.0.txt
@@ -0,0 +1,9 @@
+Written by hand.
+Test case for package moved into a parent module.
+
+-- .mod --
+module example.com/join/subpkg
+-- .info --
+{"Version": "v1.0.0"}
+-- x.go --
+package subpkg
diff --git a/vendor/cmd/go/testdata/mod/example.com_join_subpkg_v1.1.0.txt b/vendor/cmd/go/testdata/mod/example.com_join_subpkg_v1.1.0.txt
new file mode 100644
index 0000000..9eb823a
--- /dev/null
+++ b/vendor/cmd/go/testdata/mod/example.com_join_subpkg_v1.1.0.txt
@@ -0,0 +1,9 @@
+Written by hand.
+Test case for package moved into a parent module.
+
+-- .mod --
+module example.com/join/subpkg
+
+require example.com/join v1.1.0
+-- .info --
+{"Version": "v1.1.0"}
diff --git a/vendor/cmd/go/testdata/mod/example.com_join_v1.0.0.txt b/vendor/cmd/go/testdata/mod/example.com_join_v1.0.0.txt
new file mode 100644
index 0000000..84c68b1
--- /dev/null
+++ b/vendor/cmd/go/testdata/mod/example.com_join_v1.0.0.txt
@@ -0,0 +1,7 @@
+Written by hand.
+Test case for package moved into a parent module.
+
+-- .mod --
+module example.com/join
+-- .info --
+{"Version": "v1.0.0"}
diff --git a/vendor/cmd/go/testdata/mod/example.com_join_v1.1.0.txt b/vendor/cmd/go/testdata/mod/example.com_join_v1.1.0.txt
new file mode 100644
index 0000000..5f92036
--- /dev/null
+++ b/vendor/cmd/go/testdata/mod/example.com_join_v1.1.0.txt
@@ -0,0 +1,9 @@
+Written by hand.
+Test case for package moved into a parent module.
+
+-- .mod --
+module example.com/join
+-- .info --
+{"Version": "v1.1.0"}
+-- subpkg/x.go --
+package subpkg
diff --git a/vendor/cmd/go/testdata/mod/example.com_split_subpkg_v1.1.0.txt b/vendor/cmd/go/testdata/mod/example.com_split_subpkg_v1.1.0.txt
new file mode 100644
index 0000000..b197b66
--- /dev/null
+++ b/vendor/cmd/go/testdata/mod/example.com_split_subpkg_v1.1.0.txt
@@ -0,0 +1,11 @@
+Written by hand.
+Test case for getting a package that has been moved to a different module.
+
+-- .mod --
+module example.com/split/subpkg
+
+require example.com/split v1.1.0
+-- .info --
+{"Version": "v1.1.0"}
+-- x.go --
+package subpkg
diff --git a/vendor/cmd/go/testdata/mod/example.com_split_v1.0.0.txt b/vendor/cmd/go/testdata/mod/example.com_split_v1.0.0.txt
new file mode 100644
index 0000000..b706e59
--- /dev/null
+++ b/vendor/cmd/go/testdata/mod/example.com_split_v1.0.0.txt
@@ -0,0 +1,9 @@
+Written by hand.
+Test case for getting a package that has been moved to a different module.
+
+-- .mod --
+module example.com/split
+-- .info --
+{"Version": "v1.0.0"}
+-- subpkg/x.go --
+package subpkg
diff --git a/vendor/cmd/go/testdata/mod/example.com_split_v1.1.0.txt b/vendor/cmd/go/testdata/mod/example.com_split_v1.1.0.txt
new file mode 100644
index 0000000..d38971f
--- /dev/null
+++ b/vendor/cmd/go/testdata/mod/example.com_split_v1.1.0.txt
@@ -0,0 +1,9 @@
+Written by hand.
+Test case for getting a package that has been moved to a different module.
+
+-- .mod --
+module example.com/split
+
+require example.com/split/subpkg v1.1.0
+-- .info --
+{"Version": "v1.1.0"}
diff --git a/vendor/cmd/go/testdata/mod/golang.org_x_text_v0.0.0-20170915032832-14c0d48ead0c.txt b/vendor/cmd/go/testdata/mod/golang.org_x_text_v0.0.0-20170915032832-14c0d48ead0c.txt
index e03b3ce..f4f50cd 100644
--- a/vendor/cmd/go/testdata/mod/golang.org_x_text_v0.0.0-20170915032832-14c0d48ead0c.txt
+++ b/vendor/cmd/go/testdata/mod/golang.org_x_text_v0.0.0-20170915032832-14c0d48ead0c.txt
@@ -6,6 +6,8 @@
 {"Version":"v0.0.0-20170915032832-14c0d48ead0c","Name":"v0.0.0-20170915032832-14c0d48ead0c","Short":"14c0d48ead0c","Time":"2017-09-15T03:28:32Z"}
 -- go.mod --
 module golang.org/x/text
+-- unused/unused.go --
+package unused
 -- language/lang.go --
 // Copyright 2018 The Go Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style
diff --git a/vendor/cmd/go/testdata/mod/golang.org_x_text_v0.3.0.txt b/vendor/cmd/go/testdata/mod/golang.org_x_text_v0.3.0.txt
index 6932642..5561afa 100644
--- a/vendor/cmd/go/testdata/mod/golang.org_x_text_v0.3.0.txt
+++ b/vendor/cmd/go/testdata/mod/golang.org_x_text_v0.3.0.txt
@@ -6,6 +6,8 @@
 {"Version":"v0.3.0","Name":"","Short":"","Time":"2017-09-16T03:28:32Z"}
 -- go.mod --
 module golang.org/x/text
+-- unused/unused.go --
+package unused
 -- language/lang.go --
 // Copyright 2018 The Go Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style
diff --git a/vendor/cmd/go/testdata/mod/gopkg.in_dummy.v2-unstable_v2.0.0.txt b/vendor/cmd/go/testdata/mod/gopkg.in_dummy.v2-unstable_v2.0.0.txt
new file mode 100644
index 0000000..f174159
--- /dev/null
+++ b/vendor/cmd/go/testdata/mod/gopkg.in_dummy.v2-unstable_v2.0.0.txt
@@ -0,0 +1,9 @@
+gopkg.in/dummy.v2-unstable v2.0.0
+written by hand
+
+-- .mod --
+module gopkg.in/dummy.v2-unstable
+-- .info --
+{"Version":"v2.0.0"}
+-- dummy.go --
+package dummy
diff --git a/vendor/cmd/go/testdata/mod/research.swtch.com_vgo-tour_v1.0.0.txt b/vendor/cmd/go/testdata/mod/research.swtch.com_vgo-tour_v1.0.0.txt
new file mode 100644
index 0000000..0f060dc
--- /dev/null
+++ b/vendor/cmd/go/testdata/mod/research.swtch.com_vgo-tour_v1.0.0.txt
@@ -0,0 +1,23 @@
+research.swtch.com/vgo-tour@v1.0.0
+
+-- .mod --
+module "research.swtch.com/vgo-tour"
+-- .info --
+{"Version":"v1.0.0","Name":"84de74b35823c1e49634f2262f1a58cfc951ebae","Short":"84de74b35823","Time":"2018-02-20T00:04:00Z"}
+-- go.mod --
+module "research.swtch.com/vgo-tour"
+-- hello.go --
+// Copyright 2018 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package main
+
+import (
+	"fmt"
+	"rsc.io/quote"
+)
+
+func main() {
+	fmt.Println(quote.Hello())
+}
diff --git a/vendor/cmd/go/testdata/mod/rsc.io_fortune_v1.0.0.txt b/vendor/cmd/go/testdata/mod/rsc.io_fortune_v1.0.0.txt
new file mode 100644
index 0000000..d8a71f3
--- /dev/null
+++ b/vendor/cmd/go/testdata/mod/rsc.io_fortune_v1.0.0.txt
@@ -0,0 +1,15 @@
+rsc.io/fortune v1.0.0
+written by hand
+
+-- .mod --
+module rsc.io/fortune
+-- .info --
+{"Version":"v1.0.0"}
+-- fortune.go --
+package main
+
+import "rsc.io/quote"
+
+func main() {
+	println(quote.Hello())
+}
diff --git a/vendor/cmd/go/testdata/mod/rsc.io_fortune_v2_v2.0.0.txt b/vendor/cmd/go/testdata/mod/rsc.io_fortune_v2_v2.0.0.txt
new file mode 100644
index 0000000..cfa91f0
--- /dev/null
+++ b/vendor/cmd/go/testdata/mod/rsc.io_fortune_v2_v2.0.0.txt
@@ -0,0 +1,15 @@
+rsc.io/fortune v2.0.0
+written by hand
+
+-- .mod --
+module rsc.io/fortune/v2
+-- .info --
+{"Version":"v2.0.0"}
+-- fortune.go --
+package main
+
+import "rsc.io/quote"
+
+func main() {
+	println(quote.Hello())
+}
diff --git a/vendor/cmd/go/testdata/mod/rsc.io_sampler_v1.3.0.txt b/vendor/cmd/go/testdata/mod/rsc.io_sampler_v1.3.0.txt
index 000f212..febe51f 100644
--- a/vendor/cmd/go/testdata/mod/rsc.io_sampler_v1.3.0.txt
+++ b/vendor/cmd/go/testdata/mod/rsc.io_sampler_v1.3.0.txt
@@ -36,6 +36,7 @@
 	"testing"
 
 	"golang.org/x/text/language"
+	_ "rsc.io/testonly"
 )
 
 var glassTests = []struct {
diff --git a/vendor/cmd/go/testdata/mod/rsc.io_testonly_v1.0.0.txt b/vendor/cmd/go/testdata/mod/rsc.io_testonly_v1.0.0.txt
new file mode 100644
index 0000000..dfb8ca2
--- /dev/null
+++ b/vendor/cmd/go/testdata/mod/rsc.io_testonly_v1.0.0.txt
@@ -0,0 +1,9 @@
+rsc.io/testonly v1.0.0
+written by hand
+
+-- .mod --
+module rsc.io/testonly
+-- .info --
+{"Version":"v1.0.0"}
+-- testonly.go --
+package testonly
diff --git a/vendor/cmd/go/testdata/script/build_cache_output.txt b/vendor/cmd/go/testdata/script/build_cache_output.txt
index d80c7f2..ee4099e 100644
--- a/vendor/cmd/go/testdata/script/build_cache_output.txt
+++ b/vendor/cmd/go/testdata/script/build_cache_output.txt
@@ -6,14 +6,58 @@
 
 # Building a trivial non-main package should run compiler the first time.
 go build -x -gcflags=-m lib.go
-stderr 'compile( |\.exe)'
+stderr 'compile( |\.exe"?)'
 stderr 'lib.go:2.* can inline f'
 
 # ... but not the second, even though it still prints the compiler output.
 go build -x -gcflags=-m lib.go
-! stderr 'compile( |\.exe)'
+! stderr 'compile( |\.exe"?)'
 stderr 'lib.go:2.* can inline f'
 
+# Building a trivial main package should run the compiler and linker the first time.
+go build -x -gcflags=-m -ldflags='-v -w' main.go
+stderr 'compile( |\.exe"?)'
+stderr 'main.go:2.* can inline main' # from compiler
+stderr 'link(\.exe"?)? -'
+stderr '\d+ symbols' # from linker
+
+# ... but not the second, even though it still prints the compiler and linker output.
+go build -x -gcflags=-m -ldflags='-v -w' main.go
+! stderr 'compile( |\.exe"?)'
+stderr 'main.go:2.* can inline main' # from compiler
+! stderr 'link(\.exe"?)? -'
+stderr '\d+ symbols' # from linker
+
+# Running a test should run the compiler, linker, and the test the first time.
+go test -v -x -gcflags=-m -ldflags=-v p_test.go
+stderr 'compile( |\.exe"?)'
+stderr 'p_test.go:.*can inline Test' # from compile of p_test
+stderr 'testmain\.go:.*inlin' # from compile of testmain
+stderr 'link(\.exe"?)? -'
+stderr '\d+ symbols' # from linker
+stderr 'p\.test( |\.exe"?)'
+stdout 'TEST' # from test
+
+# ... but not the second, even though it still prints the compiler, linker, and test output.
+go test -v -x -gcflags=-m -ldflags=-v p_test.go
+! stderr 'compile( |\.exe"?)'
+stderr 'p_test.go:.*can inline Test' # from compile of p_test
+stderr 'testmain\.go:.*inlin' # from compile of testmain
+! stderr 'link(\.exe"?)? -'
+stderr '\d+ symbols' # from linker
+! stderr 'p\.test( |\.exe"?)'
+stdout 'TEST' # from test
+
+
 -- lib.go --
 package p
 func f(x *int) *int { return x }
+
+-- main.go --
+package main
+func main() {}
+
+-- p_test.go --
+package p
+import "testing"
+func Test(t *testing.T) {println("TEST")}
diff --git a/vendor/cmd/go/testdata/script/cover_atomic_pkgall.txt b/vendor/cmd/go/testdata/script/cover_atomic_pkgall.txt
new file mode 100644
index 0000000..c122c05
--- /dev/null
+++ b/vendor/cmd/go/testdata/script/cover_atomic_pkgall.txt
@@ -0,0 +1,23 @@
+[short] skip
+
+go test -coverpkg=all -covermode=atomic x
+stdout ok[\s\S]+?coverage
+
+[!race] stop
+
+go test -coverpkg=all -race x
+stdout ok[\s\S]+?coverage
+
+-- x/x.go --
+package x
+
+import _ "sync/atomic"
+
+func F() {}
+
+-- x/x_test.go --
+package x
+
+import "testing"
+
+func TestF(t *testing.T) { F() }
diff --git a/vendor/cmd/go/testdata/script/cover_pkgall_runtime.txt b/vendor/cmd/go/testdata/script/cover_pkgall_runtime.txt
new file mode 100644
index 0000000..5d169d6
--- /dev/null
+++ b/vendor/cmd/go/testdata/script/cover_pkgall_runtime.txt
@@ -0,0 +1,21 @@
+# Issue 23882
+
+[short] skip
+
+go test -coverpkg=all x
+stdout ok[\s\S]+?coverage
+
+[!race] stop
+
+go test -coverpkg=all -race x
+stdout ok[\s\S]+?coverage
+
+-- x/x.go --
+package x
+import _ "runtime"
+func F() {}
+
+-- x/x_test.go --
+package x
+import "testing"
+func TestF(t *testing.T) { F() }
diff --git a/vendor/cmd/go/testdata/script/cpu_profile_twice.txt b/vendor/cmd/go/testdata/script/cpu_profile_twice.txt
new file mode 100644
index 0000000..142d5ee
--- /dev/null
+++ b/vendor/cmd/go/testdata/script/cpu_profile_twice.txt
@@ -0,0 +1,20 @@
+# Issue 23150
+
+[short] skip
+
+go test -o=$WORK/x.test -cpuprofile=$WORK/cpu_profile_twice.out x
+rm $WORK/cpu_profile_twice.out
+
+go test -o=$WORK/x.test -cpuprofile=$WORK/cpu_profile_twice.out x
+exists $WORK/cpu_profile_twice.out
+
+
+-- x/x_test.go --
+package x_test
+import (
+    "testing"
+    "time"
+)
+func TestSleep(t *testing.T) {
+    time.Sleep(10 * time.Millisecond)
+}
diff --git a/vendor/cmd/go/testdata/script/gcflags_patterns.txt b/vendor/cmd/go/testdata/script/gcflags_patterns.txt
new file mode 100644
index 0000000..fe2cf6f
--- /dev/null
+++ b/vendor/cmd/go/testdata/script/gcflags_patterns.txt
@@ -0,0 +1,71 @@
+[!gc] skip 'using -gcflags and -ldflags'
+
+# -gcflags=-e applies to named packages, not dependencies
+go build -n -v -gcflags=-e z1 z2
+stderr 'compile.* -e .*-p z1'
+stderr 'compile.* -e .*-p z2'
+stderr 'compile.* -p y'
+! stderr 'compile.* -e .*-p [^z]'
+
+# -gcflags can specify package=flags, and can be repeated; last match wins
+go build -n -v -gcflags=-e -gcflags=z1=-N z1 z2
+stderr 'compile.* -N .*-p z1'
+! stderr 'compile.* -e .*-p z1'
+! stderr 'compile.* -N .*-p z2'
+stderr 'compile.* -e .*-p z2'
+stderr 'compile.* -p y'
+! stderr 'compile.* -e .*-p [^z]'
+! stderr 'compile.* -N .*-p [^z]'
+
+# -gcflags can have arbitrary spaces around the flags
+go build -n -v -gcflags='  z1 =  	-e 	' z1
+stderr 'compile.* -e .*-p z1'
+
+# -ldflags for implicit test package applies to test binary
+go test -c -n -gcflags=-N -ldflags=-X=x.y=z z1
+stderr 'compile.* -N .*z_test.go'
+stderr 'link.* -X=x.y=z'
+
+# -ldflags for explicit test package applies to test binary
+go test -c -n -gcflags=z1=-N -ldflags=z1=-X=x.y=z z1
+stderr 'compile.* -N .*z_test.go'
+stderr 'link.* -X=x.y=z'
+
+# -ldflags applies to link of command
+go build -n -ldflags=-X=math.pi=3 my/cmd/prog
+stderr 'link.* -X=math.pi=3'
+
+# -ldflags applies to link of command even with strange directory name
+go build -n -ldflags=-X=math.pi=3 my/cmd/prog/
+stderr 'link.* -X=math.pi=3'
+
+# -ldflags applies to current directory
+cd my/cmd/prog
+go build -n -ldflags=-X=math.pi=3
+stderr 'link.* -X=math.pi=3'
+
+# -ldflags applies to current directory even if GOPATH is funny
+[windows] cd $WORK/GoPath/src/my/cmd/prog
+[darwin] cd $WORK/GoPath/src/my/cmd/prog
+go build -n -ldflags=-X=math.pi=3
+stderr 'link.* -X=math.pi=3'
+
+-- z1/z.go --
+package z1
+import _ "y"
+import _ "z2"
+
+-- z1/z_test.go --
+package z1_test
+import "testing"
+func Test(t *testing.T) {}
+
+-- z2/z.go --
+package z2
+
+-- y/y.go --
+package y
+
+-- my/cmd/prog/prog.go --
+package main
+func main() {}
diff --git a/vendor/cmd/go/testdata/script/get_with_git_trace.txt b/vendor/cmd/go/testdata/script/get_with_git_trace.txt
new file mode 100644
index 0000000..93341a3
--- /dev/null
+++ b/vendor/cmd/go/testdata/script/get_with_git_trace.txt
@@ -0,0 +1,7 @@
+env GIT_TRACE=1
+
+[!net] skip
+[!exec:git] skip
+
+# go get should be success when GIT_TRACE set
+go get golang.org/x/text
diff --git a/vendor/cmd/go/testdata/script/list_bad_import.txt b/vendor/cmd/go/testdata/script/list_bad_import.txt
new file mode 100644
index 0000000..ba66b09
--- /dev/null
+++ b/vendor/cmd/go/testdata/script/list_bad_import.txt
@@ -0,0 +1,67 @@
+# This test matches mod_list_bad_import, but in GOPATH mode.
+# Please keep them in sync.
+
+env GO111MODULE=off
+cd example.com
+
+# Without -e, listing an otherwise-valid package with an unsatisfied direct import should fail.
+# BUG: Today it succeeds.
+go list -f '{{if .Error}}error{{end}} {{if .Incomplete}}incomplete{{end}} {{range .DepsErrors}}bad dep: {{.Err}}{{end}}' example.com/direct
+! stdout ^error
+stdout 'incomplete'
+stdout 'bad dep: .*example.com[/\\]notfound'
+
+# Listing with -deps should also fail.
+# BUG: Today, it does not.
+# ! go list -deps example.com/direct
+# stderr example.com[/\\]notfound
+go list -deps example.com/direct
+stdout example.com/notfound
+
+
+# Listing an otherwise-valid package that imports some *other* package with an
+# unsatisfied import should also fail.
+# BUG: Today, it succeeds.
+go list -f '{{if .Error}}error{{end}} {{if .Incomplete}}incomplete{{end}} {{range .DepsErrors}}bad dep: {{.Err}}{{end}}' example.com/indirect
+! stdout ^error
+stdout incomplete
+stdout 'bad dep: .*example.com[/\\]notfound'
+
+# Again, -deps should fail.
+# BUG: Again, it does not.
+# ! go list -deps example.com/indirect
+# stderr example.com[/\\]notfound
+go list -deps example.com/indirect
+stdout example.com/notfound
+
+
+# Listing the missing dependency directly should fail outright...
+! go list -f '{{if .Error}}error{{end}} {{if .Incomplete}}incomplete{{end}}' example.com/notfound
+stderr 'no Go files in .*example.com[/\\]notfound'
+! stdout error
+! stdout incomplete
+
+# ...but listing with -e should succeed.
+go list -e -f '{{if .Error}}error{{end}} {{if .Incomplete}}incomplete{{end}}' example.com/notfound
+stdout error
+stdout incomplete
+
+
+# The pattern "all" should match only packages that acutally exist,
+# ignoring those whose existence is merely implied by imports.
+go list -e -f '{{.ImportPath}}' all
+stdout example.com/direct
+stdout example.com/indirect
+! stdout example.com/notfound
+
+
+-- example.com/direct/direct.go --
+package direct
+import _ "example.com/notfound"
+
+-- example.com/indirect/indirect.go --
+package indirect
+import _ "example.com/direct"
+
+-- example.com/notfound/README --
+This directory intentionally left blank.
diff --git a/vendor/cmd/go/testdata/script/list_compiled_imports.txt b/vendor/cmd/go/testdata/script/list_compiled_imports.txt
new file mode 100644
index 0000000..e6f5abb
--- /dev/null
+++ b/vendor/cmd/go/testdata/script/list_compiled_imports.txt
@@ -0,0 +1,29 @@
+[!cgo] skip
+
+# go list should report import "C"
+cd x
+go list -f '{{.Imports}}'
+! stdout runtime/cgo
+! stdout unsafe
+! stdout syscall
+stdout C
+stdout unicode
+stdout unicode/utf16
+
+# go list -compiled should report imports in compiled files as well,
+# adding "runtime/cgo", "unsafe", and "syscall" but not dropping "C".
+go list -compiled -f '{{.Imports}}'
+stdout runtime/cgo
+stdout unsafe
+stdout syscall
+stdout C
+stdout unicode
+stdout unicode/utf16
+
+-- x/x.go --
+package x
+import "C"
+import "unicode" // does not use unsafe, syscall, runtime/cgo, unicode/utf16
+-- x/x1.go --
+package x
+import "unicode/utf16" // does not use unsafe, syscall, runtime/cgo, unicode
diff --git a/vendor/cmd/go/testdata/script/list_test_imports.txt b/vendor/cmd/go/testdata/script/list_test_imports.txt
new file mode 100644
index 0000000..51d1ce9
--- /dev/null
+++ b/vendor/cmd/go/testdata/script/list_test_imports.txt
@@ -0,0 +1,19 @@
+# issue 26880: list with tests has wrong variant in imports
+go list -test -f '{{.ImportPath}}:{{with .Imports}} {{join . ", "}}{{end}}' a b
+cmp stdout imports.txt
+
+-- a/a.go --
+package a; import _ "b"
+-- b/b.go --
+package b
+-- b/b_test.go --
+package b
+-- b/b_x_test.go --
+package b_test; import _ "a"
+
+-- imports.txt --
+a: b
+b:
+b.test: b [b.test], b_test [b.test], os, testing, testing/internal/testdeps
+b [b.test]:
+b_test [b.test]: a [b.test]
diff --git a/vendor/cmd/go/testdata/script/mod_bad_domain.txt b/vendor/cmd/go/testdata/script/mod_bad_domain.txt
index 236564e..c9fd044 100644
--- a/vendor/cmd/go/testdata/script/mod_bad_domain.txt
+++ b/vendor/cmd/go/testdata/script/mod_bad_domain.txt
@@ -2,20 +2,28 @@
 
 # explicit get should report errors about bad names
 ! go get appengine
-stderr 'cannot find module providing package appengine'
+stderr 'malformed module path "appengine": missing dot in first path element'
 ! go get x/y.z
-stderr 'cannot find module providing package x/y.z'
+stderr 'malformed module path "x/y.z": missing dot in first path element'
 
-# build should skip over appengine imports
-! go build
-! stderr appengine
+# build should report all unsatisfied imports,
+# but should be more definitive about non-module import paths
+! go build ./useappengine
+stderr 'cannot find package'
+! go build ./usenonexistent
 stderr 'cannot find module providing package nonexistent.rsc.io'
 
+# go mod vendor and go mod tidy should ignore appengine imports.
+rm usenonexistent/x.go
+go mod tidy
+go mod vendor
+
 -- go.mod --
 module x
 
--- x.go --
-package x
-
-import _ "appengine"
+-- useappengine/x.go --
+package useappengine
+import _ "appengine" // package does not exist
+-- usenonexistent/x.go --
+package usenonexistent
 import _ "nonexistent.rsc.io" // domain does not exist
diff --git a/vendor/cmd/go/testdata/script/mod_download.txt b/vendor/cmd/go/testdata/script/mod_download.txt
new file mode 100644
index 0000000..6be6acb
--- /dev/null
+++ b/vendor/cmd/go/testdata/script/mod_download.txt
@@ -0,0 +1,64 @@
+env GO111MODULE=on
+
+# download with version should print nothing
+go mod download rsc.io/quote@v1.5.0
+! stdout .
+
+exists $GOPATH/pkg/mod/cache/download/rsc.io/quote/@v/v1.5.0.info
+exists $GOPATH/pkg/mod/cache/download/rsc.io/quote/@v/v1.5.0.mod
+exists $GOPATH/pkg/mod/cache/download/rsc.io/quote/@v/v1.5.0.zip
+
+# download -json with version should print JSON
+go mod download -json 'rsc.io/quote@<=v1.5.0'
+stdout '^\t"Path": "rsc.io/quote"'
+stdout '^\t"Version": "v1.5.0"'
+stdout '^\t"Info": ".*(\\\\|/)pkg(\\\\|/)mod(\\\\|/)cache(\\\\|/)download(\\\\|/)rsc.io(\\\\|/)quote(\\\\|/)@v(\\\\|/)v1.5.0.info"'
+stdout '^\t"GoMod": ".*(\\\\|/)pkg(\\\\|/)mod(\\\\|/)cache(\\\\|/)download(\\\\|/)rsc.io(\\\\|/)quote(\\\\|/)@v(\\\\|/)v1.5.0.mod"'
+stdout '^\t"Zip": ".*(\\\\|/)pkg(\\\\|/)mod(\\\\|/)cache(\\\\|/)download(\\\\|/)rsc.io(\\\\|/)quote(\\\\|/)@v(\\\\|/)v1.5.0.zip"'
+stdout '^\t"Sum": "h1:6fJa6E\+wGadANKkUMlZ0DhXFpoKlslOQDCo259XtdIE="'  # hash of testdata/mod version, not real version!
+stdout '^\t"GoModSum": "h1:LzX7hefJvL54yjefDEDHNONDjII0t9xZLPXsUe\+TKr0="'
+! stdout '"Error"'
+
+# download queries above should not have added to go.mod.
+go list -m all
+! stdout rsc.io
+
+# add to go.mod so we can test non-query downloads
+go mod edit -require rsc.io/quote@v1.5.2
+! exists $GOPATH/pkg/mod/cache/download/rsc.io/quote/@v/v1.5.2.info
+! exists $GOPATH/pkg/mod/cache/download/rsc.io/quote/@v/v1.5.2.mod
+! exists $GOPATH/pkg/mod/cache/download/rsc.io/quote/@v/v1.5.2.zip
+
+# module loading will page in the info and mod files
+go list -m all
+exists $GOPATH/pkg/mod/cache/download/rsc.io/quote/@v/v1.5.2.info
+exists $GOPATH/pkg/mod/cache/download/rsc.io/quote/@v/v1.5.2.mod
+! exists $GOPATH/pkg/mod/cache/download/rsc.io/quote/@v/v1.5.2.zip
+
+# download will fetch and unpack the zip file
+go mod download
+exists $GOPATH/pkg/mod/cache/download/rsc.io/quote/@v/v1.5.2.info
+exists $GOPATH/pkg/mod/cache/download/rsc.io/quote/@v/v1.5.2.mod
+exists $GOPATH/pkg/mod/cache/download/rsc.io/quote/@v/v1.5.2.zip
+exists $GOPATH/pkg/mod/rsc.io/quote@v1.5.2
+
+go mod download -json
+stdout '^\t"Path": "rsc.io/quote"'
+stdout '^\t"Version": "v1.5.2"'
+stdout '^\t"Info": ".*(\\\\|/)pkg(\\\\|/)mod(\\\\|/)cache(\\\\|/)download(\\\\|/)rsc.io(\\\\|/)quote(\\\\|/)@v(\\\\|/)v1.5.2.info"'
+stdout '^\t"GoMod": ".*(\\\\|/)pkg(\\\\|/)mod(\\\\|/)cache(\\\\|/)download(\\\\|/)rsc.io(\\\\|/)quote(\\\\|/)@v(\\\\|/)v1.5.2.mod"'
+stdout '^\t"Zip": ".*(\\\\|/)pkg(\\\\|/)mod(\\\\|/)cache(\\\\|/)download(\\\\|/)rsc.io(\\\\|/)quote(\\\\|/)@v(\\\\|/)v1.5.2.zip"'
+stdout '^\t"Dir": ".*(\\\\|/)pkg(\\\\|/)mod(\\\\|/)rsc.io(\\\\|/)quote@v1.5.2"'
+
+# download will follow replacements
+go mod edit -require rsc.io/quote@v1.5.1 -replace rsc.io/quote@v1.5.1=rsc.io/quote@v1.5.3-pre1
+go mod download
+! exists $GOPATH/pkg/mod/cache/download/rsc.io/quote/@v/v1.5.1.zip
+exists $GOPATH/pkg/mod/cache/download/rsc.io/quote/@v/v1.5.3-pre1.zip
+
+# download will not follow replacements for explicit module queries
+go mod download -json rsc.io/quote@v1.5.1
+exists $GOPATH/pkg/mod/cache/download/rsc.io/quote/@v/v1.5.1.zip
+
+-- go.mod --
+module m
diff --git a/vendor/cmd/go/testdata/script/mod_enabled.txt b/vendor/cmd/go/testdata/script/mod_enabled.txt
index 4901b9c..8eef870 100644
--- a/vendor/cmd/go/testdata/script/mod_enabled.txt
+++ b/vendor/cmd/go/testdata/script/mod_enabled.txt
@@ -65,6 +65,15 @@
 go env GOMOD
 ! stdout .+
 
+# GO111MODULE=auto should ignore and warn about /tmp/go.mod
+env GO111MODULE=auto
+cp $GOPATH/src/x/y/z/go.mod $WORK/tmp/go.mod
+mkdir $WORK/tmp/mydir
+cd $WORK/tmp/mydir
+go env GOMOD
+! stdout .+
+stderr '^go: warning: ignoring go.mod in system temp root '
+
 -- $GOPATH/src/x/y/z/go.mod --
 module x/y/z
 -- $GOPATH/src/x/y/z/w/w.txt --
diff --git a/vendor/cmd/go/testdata/script/mod_fs_patterns.txt b/vendor/cmd/go/testdata/script/mod_fs_patterns.txt
index b5350c3..d7d3e03 100644
--- a/vendor/cmd/go/testdata/script/mod_fs_patterns.txt
+++ b/vendor/cmd/go/testdata/script/mod_fs_patterns.txt
@@ -28,6 +28,18 @@
 stdout ^m/y$
 ! stdout ^m/y/z
 
+# non-existent directory should not prompt lookups
+! go build -mod=readonly example.com/nonexist
+stderr 'import lookup disabled'
+
+! go build -mod=readonly ./nonexist
+! stderr 'import lookup disabled'
+stderr '^go: no such directory ./nonexist'
+
+! go build -mod=readonly ./go.mod
+! stderr 'import lookup disabled'
+stderr '^go: ./go.mod is not a directory'
+
 -- x/go.mod --
 module m
 
diff --git a/vendor/cmd/go/testdata/script/mod_get_commit.txt b/vendor/cmd/go/testdata/script/mod_get_commit.txt
index 97a1078..589a791 100644
--- a/vendor/cmd/go/testdata/script/mod_get_commit.txt
+++ b/vendor/cmd/go/testdata/script/mod_get_commit.txt
@@ -2,12 +2,6 @@
 
 # @commit should resolve
 
-# go get should skip build with no Go files in root
-go get golang.org/x/text@14c0d48
-
-# ... and go get should skip build with -m
-go get -m golang.org/x/text@14c0d48
-
 # golang.org/x/text/language@commit should not resolve with -m,
 # because that's not a module path.
 ! go get -m golang.org/x/text/language@14c0d48
@@ -17,10 +11,25 @@
 go get -d -x golang.org/x/text/language@14c0d48
 ! stderr 'compile|cp|gccgo .*language\.a$'
 
+# go get should skip build with no Go files in root
+go get golang.org/x/text@14c0d48
+
+# ... and go get should skip build with -m
+go get -m golang.org/x/text@14c0d48
+
 # dropping -d, we should see a build.
 go get -x golang.org/x/text/language@14c0d48
 stderr 'compile|cp|gccgo .*language\.a$'
 
+# BUG: after the build, the package should not be stale, as 'go install' would
+# not do anything further.
+go list -f '{{.Stale}}' golang.org/x/text/language
+stdout ^true
+
+# install after get should not run the compiler again.
+go install -x golang.org/x/text/language
+! stderr 'compile|cp|gccgo .*language\.a$'
+
 # even with -d, we should see an error for unknown packages.
 ! go get -d -x golang.org/x/text/foo@14c0d48
 
@@ -36,8 +45,8 @@
 go mod edit -require rsc.io/quote@23179ee
 grep 'rsc.io/quote 23179ee' go.mod
 
-# but go mod fix fixes them
-go mod fix
+# but other commands fix them
+go mod graph
 grep 'rsc.io/quote v1.5.1' go.mod
 
 -- go.mod --
diff --git a/vendor/cmd/go/testdata/script/mod_get_indirect.txt b/vendor/cmd/go/testdata/script/mod_get_indirect.txt
index 8388ed1..3ae5833 100644
--- a/vendor/cmd/go/testdata/script/mod_get_indirect.txt
+++ b/vendor/cmd/go/testdata/script/mod_get_indirect.txt
@@ -11,8 +11,14 @@
 stdout '^golang.org/x/text [v0-9a-f\.-]+ // indirect'
 grep 'golang.org/x/text [v0-9a-f\.-]+ // indirect' go.mod
 
-# indirect tag should be removed upon seeing direct import
+# importing an empty module root as a package makes it direct.
+# TODO(bcmills): This doesn't seem correct. Fix is in the next change.
 cp $WORK/tmp/usetext.go x.go
+go list -e
+grep 'golang.org/x/text [v0-9a-f\.-]+ // indirect' go.mod
+
+# indirect tag should be removed upon seeing direct import.
+cp $WORK/tmp/uselang.go x.go
 go list
 grep 'rsc.io/quote v1.5.2$' go.mod
 grep 'golang.org/x/text [v0-9a-f\.-]+$' go.mod
@@ -24,7 +30,7 @@
 grep 'golang.org/x/text [v0-9a-f\.-]+ // indirect' go.mod
 
 # requirement should be dropped entirely if not needed
-cp $WORK/tmp/usetext.go x.go
+cp $WORK/tmp/uselang.go x.go
 go mod tidy
 ! grep rsc.io/quote go.mod
 grep 'golang.org/x/text [v0-9a-f\.-]+$' go.mod
@@ -37,6 +43,9 @@
 -- $WORK/tmp/usetext.go --
 package x
 import _ "golang.org/x/text"
+-- $WORK/tmp/uselang.go --
+package x
+import _ "golang.org/x/text/language"
 -- $WORK/tmp/usequote.go --
 package x
 import _ "rsc.io/quote"
diff --git a/vendor/cmd/go/testdata/script/mod_get_local.txt b/vendor/cmd/go/testdata/script/mod_get_local.txt
new file mode 100644
index 0000000..4edda99
--- /dev/null
+++ b/vendor/cmd/go/testdata/script/mod_get_local.txt
@@ -0,0 +1,61 @@
+# Test 'go get' with a local module with a name that is not valid for network lookup.
+
+env GO111MODULE=on
+go mod edit -fmt
+cp go.mod go.mod.orig
+
+# 'go get -u -m' within the main module should work, even if it has a local-only name.
+cp go.mod.orig go.mod
+go get -u -m
+grep 'rsc.io/quote.*v1.5.2' go.mod
+grep 'golang.org/x/text.*v0.3.0' go.mod
+cp go.mod go.mod.implicitmod
+
+# 'go get -u -m' with the name of the main module should be equivalent to
+# 'go get -u -m' without any further arguments.
+cp go.mod.orig go.mod
+go get -u -m local
+cmp go.mod go.mod.implicitmod
+
+# 'go get -u -d' in the empty root of the main module should update the
+# dependencies of all packages in the module.
+cp go.mod.orig go.mod
+go get -u -d
+cmp go.mod go.mod.implicitmod
+
+# 'go get -u -d .' within a package in the main module updates all dependencies
+# of the main module.
+# TODO: Determine whether that behavior is a bug.
+# (https://golang.org/issue/26902)
+cp go.mod.orig go.mod
+cd uselang
+go get -u -d .
+cd ..
+grep 'rsc.io/quote.*v1.5.2' go.mod
+grep 'golang.org/x/text.*v0.3.0' go.mod
+cp go.mod go.mod.dotpkg
+
+# 'go get -u -d' with an explicit package in the main module updates
+# all dependencies of the main module.
+# TODO: Determine whether that behavior is a bug.
+# (https://golang.org/issue/26902)
+cp go.mod.orig go.mod
+go get -u -d local/uselang
+cmp go.mod go.mod.dotpkg
+
+
+-- go.mod --
+module local
+
+require (
+	golang.org/x/text v0.0.0-20170915032832-14c0d48ead0c
+	rsc.io/quote v1.3.0
+)
+
+-- uselang/uselang.go --
+package uselang
+import _ "golang.org/x/text/language"
+
+-- usequote/usequote.go --
+package usequote
+import _ "rsc.io/quote"
diff --git a/vendor/cmd/go/testdata/script/mod_get_moved.txt b/vendor/cmd/go/testdata/script/mod_get_moved.txt
new file mode 100644
index 0000000..be91449
--- /dev/null
+++ b/vendor/cmd/go/testdata/script/mod_get_moved.txt
@@ -0,0 +1,37 @@
+env GO111MODULE=on
+
+# A 'go get' that worked at a previous version should continue to work at that version,
+# even if the package was subsequently moved into a submodule.
+go mod init example.com/foo
+go get -d example.com/split/subpkg@v1.0.0
+go list -m all
+stdout 'example.com/split v1.0.0'
+
+# A 'go get' that simultaneously upgrades away conflicting package defitions is not ambiguous.
+go get example.com/split/subpkg@v1.1.0
+
+# A 'go get' without an upgrade should find the package.
+rm go.mod
+go mod init example.com/foo
+go get -d example.com/split/subpkg
+go list -m all
+stdout 'example.com/split/subpkg v1.1.0'
+
+
+# A 'go get' that worked at a previous version should continue to work at that version,
+# even if the package was subsequently moved into a parent module.
+rm go.mod
+go mod init example.com/foo
+go get -d example.com/join/subpkg@v1.0.0
+go list -m all
+stdout 'example.com/join/subpkg v1.0.0'
+
+# A 'go get' that simultaneously upgrades away conflicting package definitions is not ambiguous.
+go get example.com/join/subpkg@v1.1.0
+
+# A 'go get' without an upgrade should find the package.
+rm go.mod
+go mod init example.com/foo
+go get -d example.com/join/subpkg@v1.1.0
+go list -m all
+stdout 'example.com/join v1.1.0'
diff --git a/vendor/cmd/go/testdata/script/mod_get_none.txt b/vendor/cmd/go/testdata/script/mod_get_none.txt
new file mode 100644
index 0000000..5aec209
--- /dev/null
+++ b/vendor/cmd/go/testdata/script/mod_get_none.txt
@@ -0,0 +1,12 @@
+env GO111MODULE=on
+
+go mod init example.com/foo
+
+# 'go get bar@none' should be a no-op if module bar is not active.
+go get example.com/bar@none
+go list -m all
+! stdout example.com/bar
+
+go get example.com/bar@none
+go list -m all
+! stdout example.com/bar
diff --git a/vendor/cmd/go/testdata/script/mod_get_pseudo.txt b/vendor/cmd/go/testdata/script/mod_get_pseudo.txt
index 80bcd47..3945fdf 100644
--- a/vendor/cmd/go/testdata/script/mod_get_pseudo.txt
+++ b/vendor/cmd/go/testdata/script/mod_get_pseudo.txt
@@ -5,48 +5,26 @@
 [!exec:git] skip
 env GOPROXY=
 
+# We can resolve the @master branch without unshallowing the local repository
+# (even with older gits), so try that before we do anything else.
+# (This replicates https://golang.org/issue/26713 with git 2.7.4.)
+go get -m github.com/rsc/legacytest@master
+go list -m all
+stdout '^github.com/rsc/legacytest v2\.0\.1-0\.\d{14}-7303f7796364\+incompatible$'
+
 # get should include incompatible tags in "latest" calculation.
+go get -m github.com/rsc/legacytest@latest
 go list
 go list -m all
 stdout '^github.com/rsc/legacytest v2\.0\.0\+incompatible$'
 
-# v0.0.0-pseudo
-go get -m ...test@52853eb
+# v2.0.1-0.pseudo+incompatible
+go get -m ...test@7303f77
 go list -m all
-stdout '^github.com/rsc/legacytest v0\.0\.0-\d{14}-52853eb7b552$'
+stdout '^github.com/rsc/legacytest v2\.0\.1-0\.\d{14}-7303f7796364\+incompatible$'
 
-# v1.0.0
-go get -m ...test@7fff7f3
-go list -m all
-stdout '^github.com/rsc/legacytest v1\.0\.0$'
-
-# v1.0.1-0.pseudo
-go get -m ...test@fa4f5d6
-go list -m all
-stdout '^github.com/rsc/legacytest v1\.0\.1-0\.\d{14}-fa4f5d6a71c6$'
-
-# v1.1.0-pre (no longer on master)
-go get -m ...test@731e3b1
-go list -m all
-stdout '^github.com/rsc/legacytest v1\.1\.0-pre$'
-
-# v1.1.0-pre.0.pseudo
-go get -m ...test@fb3c628
-go list -m all
-stdout '^github.com/rsc/legacytest v1\.1\.0-pre\.0\.\d{14}-fb3c628075e3$'
-
-# v1.2.0
-go get -m ...test@9f6f860
-go list -m all
-stdout '^github.com/rsc/legacytest v1\.2\.0$'
-
-# v1.2.1-0.pseudo
-go get -m ...test@d2d4c3e
-go list -m all
-stdout '^github.com/rsc/legacytest v1\.2\.1-0\.\d{14}-d2d4c3ea6623$'
-
-# v2.0.0+incompatible by hash (back on master)
-go get -m ...test@d7ae1e4
+# v2.0.0+incompatible by tag+incompatible
+go get -m ...test@v2.0.0+incompatible
 go list -m all
 stdout '^github.com/rsc/legacytest v2\.0\.0\+incompatible$'
 
@@ -55,15 +33,45 @@
 go list -m all
 stdout '^github.com/rsc/legacytest v2\.0\.0\+incompatible$'
 
-# v2.0.0+incompatible by tag+incompatible
-go get -m ...test@v2.0.0+incompatible
+# v2.0.0+incompatible by hash (back on master)
+go get -m ...test@d7ae1e4
 go list -m all
 stdout '^github.com/rsc/legacytest v2\.0\.0\+incompatible$'
 
-# v2.0.1-0.pseudo+incompatible
-go get -m ...test@7303f77
+# v1.2.1-0.pseudo
+go get -m ...test@d2d4c3e
 go list -m all
-stdout '^github.com/rsc/legacytest v2\.0\.1-0\.\d{14}-7303f7796364\+incompatible$'
+stdout '^github.com/rsc/legacytest v1\.2\.1-0\.\d{14}-d2d4c3ea6623$'
+
+# v1.2.0
+go get -m ...test@9f6f860
+go list -m all
+stdout '^github.com/rsc/legacytest v1\.2\.0$'
+
+# v1.1.0-pre.0.pseudo
+go get -m ...test@fb3c628
+go list -m all
+stdout '^github.com/rsc/legacytest v1\.1\.0-pre\.0\.\d{14}-fb3c628075e3$'
+
+# v1.1.0-pre (no longer on master)
+go get -m ...test@731e3b1
+go list -m all
+stdout '^github.com/rsc/legacytest v1\.1\.0-pre$'
+
+# v1.0.1-0.pseudo
+go get -m ...test@fa4f5d6
+go list -m all
+stdout '^github.com/rsc/legacytest v1\.0\.1-0\.\d{14}-fa4f5d6a71c6$'
+
+# v1.0.0
+go get -m ...test@7fff7f3
+go list -m all
+stdout '^github.com/rsc/legacytest v1\.0\.0$'
+
+# v0.0.0-pseudo
+go get -m ...test@52853eb
+go list -m all
+stdout '^github.com/rsc/legacytest v0\.0\.0-\d{14}-52853eb7b552$'
 
 -- go.mod --
 module x
diff --git a/vendor/cmd/go/testdata/script/mod_gofmt_invalid.txt b/vendor/cmd/go/testdata/script/mod_gofmt_invalid.txt
new file mode 100644
index 0000000..21edc7d
--- /dev/null
+++ b/vendor/cmd/go/testdata/script/mod_gofmt_invalid.txt
@@ -0,0 +1,13 @@
+# Test for a crash in go fmt on invalid input when using modules.
+# Issue 26792.
+
+env GO111MODULE=on
+! go fmt x.go
+! stderr panic
+
+-- go.mod --
+module x
+
+-- x.go --
+// Missing package declaration.
+var V int
diff --git a/vendor/cmd/go/testdata/script/mod_gopkg_unstable.txt b/vendor/cmd/go/testdata/script/mod_gopkg_unstable.txt
new file mode 100644
index 0000000..d945cf3
--- /dev/null
+++ b/vendor/cmd/go/testdata/script/mod_gopkg_unstable.txt
@@ -0,0 +1,22 @@
+env GO111MODULE=on
+
+cp go.mod.empty go.mod
+go get -d gopkg.in/dummy.v2-unstable
+
+cp x.go.txt x.go
+cp go.mod.empty go.mod
+go list
+
+[!net] skip
+
+env GOPROXY=
+go get gopkg.in/macaroon-bakery.v2-unstable/bakery
+go list -m all
+stdout 'gopkg.in/macaroon-bakery.v2-unstable v2.0.0-[0-9]+-[0-9a-f]+$'
+
+-- go.mod.empty --
+module m
+
+-- x.go.txt --
+package x
+import _ "gopkg.in/dummy.v2-unstable"
diff --git a/vendor/cmd/go/testdata/script/mod_install_versioned.txt b/vendor/cmd/go/testdata/script/mod_install_versioned.txt
new file mode 100644
index 0000000..03986d0
--- /dev/null
+++ b/vendor/cmd/go/testdata/script/mod_install_versioned.txt
@@ -0,0 +1,12 @@
+env GO111MODULE=on
+
+go list -f '{{.Target}}' rsc.io/fortune
+! stdout fortune@v1
+stdout 'fortune(\.exe)?$'
+
+go list -f '{{.Target}}' rsc.io/fortune/v2
+! stdout v2
+stdout 'fortune(\.exe)?$'
+
+-- go.mod --
+module m
diff --git a/vendor/cmd/go/testdata/script/mod_internal.txt b/vendor/cmd/go/testdata/script/mod_internal.txt
index dfe8282..e5f5a12 100644
--- a/vendor/cmd/go/testdata/script/mod_internal.txt
+++ b/vendor/cmd/go/testdata/script/mod_internal.txt
@@ -5,18 +5,27 @@
 go mod init golang.org/x/anything
 go build .
 
+# ...and their tests...
+go test
+stdout PASS
+
 # ...but that should not leak into other modules.
 ! go build ./baddep
-stderr 'use of internal package golang.org/x/.* not allowed in golang.org/notx/useinternal$'
+stderr golang.org[/\\]notx[/\\]useinternal
+stderr 'use of internal package golang.org/x/.* not allowed'
 
 # Internal packages in the standard library should not leak into modules.
 ! go build ./fromstd
-stderr 'use of internal package internal/testenv not allowed$'
+stderr 'use of internal package internal/testenv not allowed'
 
 # Packages found via standard-library vendoring should not leak.
 ! go build ./fromstdvendor
-stderr 'use of vendored package golang_org/x/net/http/httpguts not allowed$'
+stderr 'use of vendored package golang_org/x/net/http/httpguts not allowed'
 
+env GO111MODULE=off
+! go build ./fromstdvendor
+stderr 'cannot find package "golang_org/x/net/http/httpguts" in any of:'
+env GO111MODULE=on
 
 # Dependencies should be able to use their own internal modules...
 rm go.mod
@@ -25,12 +34,12 @@
 
 # ... but other modules should not, even if they have transitive dependencies.
 ! go build .
-stderr 'use of internal package golang.org/x/.* not allowed in golang.org/notx$'
+stderr 'use of internal package golang.org/x/.* not allowed'
 
 # And transitive dependencies still should not leak.
 ! go build ./baddep
-stderr 'use of internal package golang.org/x/.* not allowed in golang.org/notx/useinternal$'
-
+stderr golang.org[/\\]notx[/\\]useinternal
+stderr 'use of internal package golang.org/x/.* not allowed'
 
 # Replacing an internal module should keep it internal to the same paths.
 rm go.mod
@@ -39,18 +48,29 @@
 go build ./throughdep
 
 ! go build ./baddep
-stderr 'use of internal package golang.org/x/.* not allowed in golang.org/notx/useinternal$'
+stderr golang.org[/\\]notx[/\\]useinternal
+stderr 'use of internal package golang.org/x/.* not allowed'
 
 go mod edit -replace golang.org/x/internal=./vendor/golang.org/x/internal
 go build ./throughdep
 
 ! go build ./baddep
-stderr 'use of internal package golang.org/x/.* not allowed in golang.org/notx/useinternal$'
+stderr golang.org[/\\]notx[/\\]useinternal
+stderr 'use of internal package golang.org/x/.* not allowed'
 
 -- useinternal.go --
 package useinternal
 import _ "golang.org/x/internal/subtle"
 
+-- useinternal_test.go --
+package useinternal_test
+import (
+	"testing"
+	_ "golang.org/x/internal/subtle"
+)
+
+func Test(*testing.T) {}
+
 -- throughdep/useinternal.go --
 package throughdep
 import _ "golang.org/x/useinternal"
diff --git a/vendor/cmd/go/testdata/script/mod_list_bad_import.txt b/vendor/cmd/go/testdata/script/mod_list_bad_import.txt
new file mode 100644
index 0000000..258eb6a
--- /dev/null
+++ b/vendor/cmd/go/testdata/script/mod_list_bad_import.txt
@@ -0,0 +1,73 @@
+# This test matches list_bad_import, but in module mode.
+# Please keep them in sync.
+
+env GO111MODULE=on
+cd example.com
+
+# Without -e, listing an otherwise-valid package with an unsatisfied direct import should fail.
+# BUG: Today it succeeds.
+go list -f '{{if .Error}}error{{end}} {{if .Incomplete}}incomplete{{end}} {{range .DepsErrors}}bad dep: {{.Err}}{{end}}' example.com/direct
+! stdout ^error
+stdout 'incomplete'
+stdout 'bad dep: .*example.com/notfound'
+
+# Listing with -deps should also fail.
+# BUG: Today, it does not.
+# ! go list -deps example.com/direct
+# stderr example.com/notfound
+go list -deps example.com/direct
+stdout example.com/notfound
+
+
+# Listing an otherwise-valid package that imports some *other* package with an
+# unsatisfied import should also fail.
+# BUG: Today, it succeeds.
+go list -f '{{if .Error}}error{{end}} {{if .Incomplete}}incomplete{{end}} {{range .DepsErrors}}bad dep: {{.Err}}{{end}}' example.com/indirect
+! stdout ^error
+stdout incomplete
+stdout 'bad dep: .*example.com/notfound'
+
+# Again, -deps should fail.
+# BUG: Again, it does not.
+# ! go list -deps example.com/indirect
+# stderr example.com/notfound
+go list -deps example.com/indirect
+stdout example.com/notfound
+
+
+# Listing the missing dependency directly should fail outright...
+! go list -f '{{if .Error}}error{{end}} {{if .Incomplete}}incomplete{{end}}' example.com/notfound
+stderr 'cannot find module providing package example.com/notfound'
+! stdout error
+! stdout incomplete
+
+# ...but listing with -e should succeed.
+go list -e -f '{{if .Error}}error{{end}} {{if .Incomplete}}incomplete{{end}}' example.com/notfound
+stdout error
+stdout incomplete
+
+
+# The pattern "all" should match only packages that acutally exist,
+# ignoring those whose existence is merely implied by imports.
+go list -e -f '{{.ImportPath}} {{.Error}}' all
+stdout example.com/direct
+stdout example.com/indirect
+# TODO: go list creates a dummy package with the import-not-found
+# but really the Error belongs on example.com/direct, and this package
+# should not be printed.
+# ! stdout example.com/notfound
+
+
+-- example.com/go.mod --
+module example.com
+
+-- example.com/direct/direct.go --
+package direct
+import _ "example.com/notfound"
+
+-- example.com/indirect/indirect.go --
+package indirect
+import _ "example.com/direct"
+
+-- example.com/notfound/README --
+This directory intentionally left blank.
diff --git a/vendor/cmd/go/testdata/script/mod_list_dir.txt b/vendor/cmd/go/testdata/script/mod_list_dir.txt
index 29cde71..800f277 100644
--- a/vendor/cmd/go/testdata/script/mod_list_dir.txt
+++ b/vendor/cmd/go/testdata/script/mod_list_dir.txt
@@ -9,11 +9,14 @@
 stdout ^math$
 go list -f '{{.ImportPath}}' .
 stdout ^x$
+! go list -f '{{.ImportPath}}' $GOPATH/pkg/mod/rsc.io/quote@v1.5.2
+stderr '^go: no such directory.*quote@v1.5.2'
+go mod download rsc.io/quote@v1.5.2
 go list -f '{{.ImportPath}}' $GOPATH/pkg/mod/rsc.io/quote@v1.5.2
 stdout '^rsc.io/quote$'
 go list -f '{{.ImportPath}}' $GOPATH/pkg/mod/rsc.io/sampler@v1.3.0
 stdout '^rsc.io/sampler$'
-go get rsc.io/sampler@v1.3.1
+go get -d rsc.io/sampler@v1.3.1
 go list -f '{{.ImportPath}}' $GOPATH/pkg/mod/rsc.io/sampler@v1.3.1
 stdout '^rsc.io/sampler$'
 ! go list -f '{{.ImportPath}}' $GOPATH/pkg/mod/rsc.io/sampler@v1.3.0
diff --git a/vendor/cmd/go/testdata/script/mod_list_test.txt b/vendor/cmd/go/testdata/script/mod_list_test.txt
new file mode 100644
index 0000000..a99e4f3
--- /dev/null
+++ b/vendor/cmd/go/testdata/script/mod_list_test.txt
@@ -0,0 +1,16 @@
+env GO111MODULE=on
+
+# go list -compiled -test must handle test-only packages
+# golang.org/issue/27097.
+go list -compiled -test
+stdout '^m$'
+stdout '^m\.test$'
+stdout '^m \[m\.test\]$'
+
+-- go.mod --
+module m
+
+-- x_test.go --
+package x
+import "testing"
+func Test(t *testing.T) {}
diff --git a/vendor/cmd/go/testdata/script/mod_patterns.txt b/vendor/cmd/go/testdata/script/mod_patterns.txt
new file mode 100644
index 0000000..4fa436b
--- /dev/null
+++ b/vendor/cmd/go/testdata/script/mod_patterns.txt
@@ -0,0 +1,66 @@
+env GO111MODULE=on
+
+cd m
+
+# 'go list all' should list all of the packages used (directly or indirectly) by
+# the packages in the main module, but no other packages from the standard
+# library or active modules.
+#
+# 'go list ...' should list packages in all active modules and the standard library.
+# But not cmd/* - see golang.org/issue/26924.
+#
+# 'go list example.com/m/...' should list packages in all modules that begin with 'example.com/m/'.
+#
+# 'go list ./...' should list only packages in the current module, not other active modules.
+#
+# Warnings about unmatched patterns should only be printed once.
+#
+# And the go command should be able to keep track of all this!
+go list -f '{{.ImportPath}}: {{.Match}}' all ... example.com/m/... ./... ./xyz...
+stdout 'example.com/m/useunicode: \[all \.\.\. example.com/m/... ./...\]'
+stdout 'example.com/m/useunsafe: \[all \.\.\. example.com/m/... ./...\]'
+[cgo] stdout 'example.com/m/useC: \[all \.\.\. example.com/m/... ./...\]'
+[!cgo] ! stdout example.com/m/useC
+stdout 'example.com/unused/useerrors: \[\.\.\.\]' # but not "all"
+stdout 'example.com/m/nested/useencoding: \[\.\.\. example.com/m/...\]' # but NOT "all" or "./..."
+stdout '^unicode: \[all \.\.\.\]'
+stdout '^unsafe: \[all \.\.\.\]'
+stdout 'index/suffixarray: \[\.\.\.\]'
+! stdout cmd/pprof # golang.org/issue/26924
+
+stderr -count=1 '^go: warning: "./xyz..." matched no packages$'
+
+env CGO_ENABLED=0
+go list -f '{{.ImportPath}}: {{.Match}}' all ... example.com/m/... ./... ./xyz...
+! stdout example.com/m/useC
+
+-- m/go.mod --
+module example.com/m
+
+require example.com/unused v0.0.0 // indirect
+replace example.com/unused => ../unused
+
+require example.com/m/nested v0.0.0 // indirect
+replace example.com/m/nested => ../nested
+
+-- m/useC/useC.go --
+package useC
+import _ "C" // "C" is a pseudo-package, not an actual one
+-- m/useunicode/useunicode.go --
+package useunicode
+import _ "unicode"
+-- m/useunsafe/useunsafe.go --
+package useunsafe
+import _ "unsafe"
+
+-- unused/go.mod --
+module example.com/unused
+-- unused/useerrors/useerrors.go --
+package useerrors
+import _ "errors"
+
+-- nested/go.mod --
+module example.com/m/nested
+-- nested/useencoding/useencoding.go --
+package useencoding
+import _ "encoding"
diff --git a/vendor/cmd/go/testdata/script/mod_readonly.txt b/vendor/cmd/go/testdata/script/mod_readonly.txt
index 5ae74a4..1b5932e 100644
--- a/vendor/cmd/go/testdata/script/mod_readonly.txt
+++ b/vendor/cmd/go/testdata/script/mod_readonly.txt
@@ -1,10 +1,13 @@
 env GO111MODULE=on
 
 # -mod=readonly must not resolve missing modules nor update go.mod
+#
+# TODO(bcmills): 'go list' should suffice, but today it does not fail due to
+# unresolved imports. When that is fixed, use 'go list' instead of 'go list all'.
 env GOFLAGS=-mod=readonly
 go mod edit -fmt
 cp go.mod go.mod.empty
-! go list
+! go list all
 stderr 'import lookup disabled by -mod=readonly'
 cmp go.mod go.mod.empty
 
diff --git a/vendor/cmd/go/testdata/script/mod_replace.txt b/vendor/cmd/go/testdata/script/mod_replace.txt
index 799a7e8..5894ed6 100644
--- a/vendor/cmd/go/testdata/script/mod_replace.txt
+++ b/vendor/cmd/go/testdata/script/mod_replace.txt
@@ -20,7 +20,7 @@
 # However, the same module can't be used as two different paths.
 go mod edit -dropreplace=rsc.io/quote/v3 -replace=not-rsc.io/quote/v3@v3.0.0=rsc.io/quote/v3@v3.0.0 -require=not-rsc.io/quote/v3@v3.0.0
 ! go build -o a4.exe .
-
+stderr 'rsc.io/quote/v3@v3.0.0 used for two different module paths \(not-rsc.io/quote/v3 and rsc.io/quote/v3\)'
 
 -- go.mod --
 module quoter
diff --git a/vendor/cmd/go/testdata/script/mod_run_internal.txt b/vendor/cmd/go/testdata/script/mod_run_internal.txt
new file mode 100644
index 0000000..653ad28
--- /dev/null
+++ b/vendor/cmd/go/testdata/script/mod_run_internal.txt
@@ -0,0 +1,46 @@
+env GO111MODULE=on
+
+go list -e -f '{{.Incomplete}}' runbad1.go
+stdout true
+! go run runbad1.go
+stderr 'use of internal package m/x/internal not allowed'
+
+go list -e -f '{{.Incomplete}}' runbad2.go
+stdout true
+! go run runbad2.go
+stderr 'use of internal package m/x/internal/y not allowed'
+
+go list -e -f '{{.Incomplete}}' runok.go
+stdout false
+go run runok.go
+
+-- go.mod --
+module m
+
+-- x/internal/internal.go --
+package internal
+
+-- x/internal/y/y.go --
+package y
+
+-- internal/internal.go --
+package internal
+
+-- internal/z/z.go --
+package z
+
+-- runbad1.go --
+package main
+import _ "m/x/internal"
+func main() {}
+
+-- runbad2.go --
+package main
+import _ "m/x/internal/y"
+func main() {}
+
+-- runok.go --
+package main
+import _ "m/internal"
+import _ "m/internal/z"
+func main() {}
diff --git a/vendor/cmd/go/testdata/script/mod_run_path.txt b/vendor/cmd/go/testdata/script/mod_run_path.txt
new file mode 100644
index 0000000..4369ee4
--- /dev/null
+++ b/vendor/cmd/go/testdata/script/mod_run_path.txt
@@ -0,0 +1,15 @@
+# Test that go run does not get confused by conflict
+# between go.mod's module path and what you'd
+# expect from GOPATH. golang.org/issue/26046.
+
+env GO111MODULE=on
+
+cd $GOPATH/src/example.com/hello
+go run main.go
+
+-- $GOPATH/src/example.com/hello/go.mod --
+module example.com/hello/v2
+
+-- $GOPATH/src/example.com/hello/main.go --
+package main
+func main() {}
diff --git a/vendor/cmd/go/testdata/script/mod_std_vendor.txt b/vendor/cmd/go/testdata/script/mod_std_vendor.txt
new file mode 100644
index 0000000..36d4ffc
--- /dev/null
+++ b/vendor/cmd/go/testdata/script/mod_std_vendor.txt
@@ -0,0 +1,19 @@
+env GO111MODULE=on
+
+go list -f '{{.TestImports}}'
+stdout net/http # from .TestImports
+
+go list -test -f '{{.Deps}}'
+stdout golang_org/x/crypto # dep of .TestImports
+
+-- go.mod --
+module m
+
+-- x.go --
+package x
+
+-- x_test.go --
+package x
+import "testing"
+import _ "net/http"
+func Test(t *testing.T) {}
diff --git a/vendor/cmd/go/testdata/script/mod_test.txt b/vendor/cmd/go/testdata/script/mod_test.txt
index a1ee8aa..caeb25a 100644
--- a/vendor/cmd/go/testdata/script/mod_test.txt
+++ b/vendor/cmd/go/testdata/script/mod_test.txt
@@ -1,11 +1,55 @@
 env GO111MODULE=on
 
+# A test in the module's root package should work.
 cd a/
+cp go.mod.empty go.mod
 go test
 stdout PASS
 
--- a/go.mod --
-module github.com/user/a
+cp go.mod.empty go.mod
+go list -deps
+! stdout ^testing$
+
+# list all should include test dependencies, like testing
+cp go.mod.empty go.mod
+go list all
+stdout ^testing$
+stdout ^rsc.io/quote$
+stdout ^rsc.io/testonly$
+
+# list -deps -tests should also include testing
+# but not deps of tests of deps (rsc.io/testonly).
+go list -deps -test
+stdout ^testing$
+stdout ^rsc.io/quote$
+! stdout ^rsc.io/testonly$
+
+# list -test all should succeed
+cp go.mod.empty go.mod
+go list -test all
+stdout '^testing'
+
+cp go.mod.empty go.mod
+go test
+stdout PASS
+
+# A test with the "_test" suffix in the module root should also work.
+cd ../b/
+go test
+stdout PASS
+
+# A test with the "_test" suffix of a *package* with a "_test" suffix should
+# even work (not that you should ever do that).
+cd ../c_test
+go test
+stdout PASS
+
+cd ../d_test
+go test
+stdout PASS
+
+-- a/go.mod.empty --
+module example.com/user/a
 
 -- a/a.go --
 package a
@@ -14,5 +58,62 @@
 package a
 
 import "testing"
+import _ "rsc.io/quote"
+
+func Test(t *testing.T) {}
+
+-- b/go.mod --
+module example.com/user/b
+
+-- b/b.go --
+package b
+
+-- b/b_test.go --
+package b_test
+
+import "testing"
+
+func Test(t *testing.T) {}
+
+-- c_test/go.mod --
+module example.com/c_test
+
+-- c_test/umm.go --
+// Package c_test is the non-test package for its import path!
+package c_test
+
+-- c_test/c_test_test.go --
+package c_test_test
+
+import "testing"
+
+func Test(t *testing.T) {}
+
+-- d_test/go.mod --
+// Package d is an ordinary package in a deceptively-named directory.
+module example.com/d
+
+-- d_test/d.go --
+package d
+
+-- d_test/d_test.go --
+package d_test
+
+import "testing"
+
+func Test(t *testing.T) {}
+
+-- e/go.mod --
+module example.com/e_test
+
+-- e/wat.go --
+// Package e_test is the non-test package for its import path,
+// in a deceptively-named directory!
+package e_test
+
+-- e/e_test.go --
+package e_test_test
+
+import "testing"
 
 func Test(t *testing.T) {}
diff --git a/vendor/cmd/go/testdata/script/mod_tidy.txt b/vendor/cmd/go/testdata/script/mod_tidy.txt
index 86434af..449aa07 100644
--- a/vendor/cmd/go/testdata/script/mod_tidy.txt
+++ b/vendor/cmd/go/testdata/script/mod_tidy.txt
@@ -10,6 +10,10 @@
 stdout '^w.1 v1.2.0'
 stdout '^z.1 v1.2.0'
 
+# empty tidy should not crash
+cd triv
+go mod tidy
+
 -- go.mod --
 module m
 
@@ -55,3 +59,6 @@
 
 -- z/sub/sub.go --
 package sub
+
+-- triv/go.mod --
+module triv
diff --git a/vendor/cmd/go/testdata/script/mod_vcs_missing.txt b/vendor/cmd/go/testdata/script/mod_vcs_missing.txt
new file mode 100644
index 0000000..fb146b4
--- /dev/null
+++ b/vendor/cmd/go/testdata/script/mod_vcs_missing.txt
@@ -0,0 +1,11 @@
+[exec:bzr] skip 'tests NOT having bzr'
+[!net] skip
+
+env GO111MODULE=on
+env GOPROXY=
+
+! go list launchpad.net/gocheck
+stderr '"bzr": executable file not found'
+
+-- go.mod --
+module m
diff --git a/vendor/cmd/go/testdata/script/mod_vendor.txt b/vendor/cmd/go/testdata/script/mod_vendor.txt
index 8915d15..b3769a8 100644
--- a/vendor/cmd/go/testdata/script/mod_vendor.txt
+++ b/vendor/cmd/go/testdata/script/mod_vendor.txt
@@ -155,6 +155,12 @@
 
 import _ "appengine"
 import _ "appengine/datastore"
+-- nonexistent.go --
+// +build alternatereality
+
+package m
+
+import _ "nonexistent.rsc.io"
 -- mypkg/go.mod --
 module me
 -- mypkg/mydir/d.go --
diff --git a/vendor/cmd/go/testdata/script/mod_vendor_build.txt b/vendor/cmd/go/testdata/script/mod_vendor_build.txt
new file mode 100644
index 0000000..7b304db
--- /dev/null
+++ b/vendor/cmd/go/testdata/script/mod_vendor_build.txt
@@ -0,0 +1,27 @@
+env GO111MODULE=on
+
+# initial conditions: using sampler v1.3.0, not listed in go.mod.
+go list -deps
+stdout rsc.io/sampler
+! grep 'rsc.io/sampler v1.3.0' go.mod
+
+# update to v1.3.1, now indirect in go.mod.
+go get rsc.io/sampler@v1.3.1
+grep 'rsc.io/sampler v1.3.1 // indirect' go.mod
+cp go.mod go.mod.good
+
+# vendoring can but should not need to make changes.
+go mod vendor
+cmp go.mod go.mod.good
+
+# go list -mod=vendor (or go build -mod=vendor) must not modify go.mod.
+# golang.org/issue/26704
+go list -mod=vendor
+cmp go.mod go.mod.good
+
+-- go.mod --
+module m
+
+-- x.go --
+package x
+import _ "rsc.io/quote"
diff --git a/vendor/cmd/go/testdata/script/mod_why.txt b/vendor/cmd/go/testdata/script/mod_why.txt
new file mode 100644
index 0000000..4d556fc
--- /dev/null
+++ b/vendor/cmd/go/testdata/script/mod_why.txt
@@ -0,0 +1,114 @@
+env GO111MODULE=on
+
+go list -test all
+stdout rsc.io/quote
+stdout golang.org/x/text/language
+
+# why a package?
+go mod why golang.org/x/text/language
+cmp stdout why-language.txt
+
+# why a module?
+go mod why -m golang.org...
+cmp stdout why-text-module.txt
+
+# why a package used only in tests?
+go mod why rsc.io/testonly
+cmp stdout why-testonly.txt
+
+# why a module used only in tests?
+go mod why -m rsc.io/testonly
+cmp stdout why-testonly.txt
+
+# test package not needed
+go mod why golang.org/x/text/unused
+cmp stdout why-unused.txt
+
+# vendor doesn't use packages used only in tests.
+go mod why -vendor rsc.io/testonly
+cmp stdout why-vendor.txt
+
+# vendor doesn't use modules used only in tests.
+go mod why -vendor -m rsc.io/testonly
+cmp stdout why-vendor-module.txt
+
+# test multiple packages
+go mod why golang.org/x/text/language golang.org/x/text/unused
+cmp stdout why-both.txt
+
+# test multiple modules
+go mod why -m rsc.io/quote rsc.io/sampler
+cmp stdout why-both-module.txt
+
+-- go.mod --
+module mymodule
+require rsc.io/quote v1.5.2
+
+-- x/x.go --
+package x
+import _ "mymodule/z"
+
+-- y/y.go --
+package y
+
+-- y/y_test.go --
+package y
+import _ "rsc.io/quote"
+
+-- z/z.go --
+package z
+import _ "mymodule/y"
+
+
+-- why-language.txt --
+# golang.org/x/text/language
+mymodule/y
+mymodule/y.test
+rsc.io/quote
+rsc.io/sampler
+golang.org/x/text/language
+-- why-unused.txt --
+# golang.org/x/text/unused
+(main module does not need package golang.org/x/text/unused)
+-- why-text-module.txt --
+# golang.org/x/text
+mymodule/y
+mymodule/y.test
+rsc.io/quote
+rsc.io/sampler
+golang.org/x/text/language
+-- why-testonly.txt --
+# rsc.io/testonly
+mymodule/y
+mymodule/y.test
+rsc.io/quote
+rsc.io/sampler
+rsc.io/sampler.test
+rsc.io/testonly
+-- why-vendor.txt --
+# rsc.io/testonly
+(main module does not need to vendor package rsc.io/testonly)
+-- why-vendor-module.txt --
+# rsc.io/testonly
+(main module does not need to vendor module rsc.io/testonly)
+-- why-both.txt --
+# golang.org/x/text/language
+mymodule/y
+mymodule/y.test
+rsc.io/quote
+rsc.io/sampler
+golang.org/x/text/language
+
+# golang.org/x/text/unused
+(main module does not need package golang.org/x/text/unused)
+-- why-both-module.txt --
+# rsc.io/quote
+mymodule/y
+mymodule/y.test
+rsc.io/quote
+
+# rsc.io/sampler
+mymodule/y
+mymodule/y.test
+rsc.io/quote
+rsc.io/sampler