cmd/go: eliminate redundancy in import error messages
This change introduces a new interface, load.ImportPathError. An error
may satisfy this by providing an ImportPath method and including the
import path in its error text. modload.ImportMissingError satisfies
this interface. load.ImportErrorf also provides a convenient way to
create an error satisfying this interface with an arbitrary message.
When load.PackageError formats its error text, it may omit the last
path on the import stack if the wrapped error satisfies
ImportPathError and has a matching path.
To make this work, PackageError.Err is now an error instead of a
string. PackageError.MarshalJSON will write Err as a string for
'go list -json' output.
When go/build.Import invokes 'go list' in module mode, it now runs
with '-e' and includes '.Error' in the output format instead of
expecting the error to be in the raw stderr text. If a package error
is printed and a directory was not found, the error will be returned
without extra decoration.
Fixes #34752
Change-Id: I2d81dab7dec19e0ae9f51f6412bc9f30433a8596
Reviewed-on: https://go-review.googlesource.com/c/go/+/199840
Run-TryBot: Jay Conrod <jayconrod@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Bryan C. Mills <bcmills@google.com>
diff --git a/src/cmd/go/internal/fmtcmd/fmt.go b/src/cmd/go/internal/fmtcmd/fmt.go
index e898d73..408af52 100644
--- a/src/cmd/go/internal/fmtcmd/fmt.go
+++ b/src/cmd/go/internal/fmtcmd/fmt.go
@@ -72,7 +72,7 @@
continue
}
if pkg.Error != nil {
- if strings.HasPrefix(pkg.Error.Err, "build constraints exclude all Go files") {
+ if strings.HasPrefix(pkg.Error.Err.Error(), "build constraints exclude all Go files") {
// Skip this error, as we will format
// all files regardless.
} else {
diff --git a/src/cmd/go/internal/get/get.go b/src/cmd/go/internal/get/get.go
index 44fd316..421f1ba 100644
--- a/src/cmd/go/internal/get/get.go
+++ b/src/cmd/go/internal/get/get.go
@@ -274,7 +274,7 @@
stk.Push(arg)
err := downloadPackage(p)
if err != nil {
- base.Errorf("%s", &load.PackageError{ImportStack: stk.Copy(), Err: err.Error()})
+ base.Errorf("%s", &load.PackageError{ImportStack: stk.Copy(), Err: err})
stk.Pop()
return
}
@@ -355,7 +355,7 @@
stk.Push(path)
err := &load.PackageError{
ImportStack: stk.Copy(),
- Err: "must be imported as " + path[j+len("vendor/"):],
+ Err: load.ImportErrorf(path, "%s must be imported as %s", path, path[j+len("vendor/"):]),
}
stk.Pop()
base.Errorf("%s", err)
diff --git a/src/cmd/go/internal/load/pkg.go b/src/cmd/go/internal/load/pkg.go
index 115bc29..6b8ecc4 100644
--- a/src/cmd/go/internal/load/pkg.go
+++ b/src/cmd/go/internal/load/pkg.go
@@ -7,6 +7,7 @@
import (
"bytes"
+ "encoding/json"
"errors"
"fmt"
"go/build"
@@ -304,9 +305,9 @@
type PackageError struct {
ImportStack []string // shortest path from package named on command line to this one
Pos string // position of error
- Err string // the error itself
- IsImportCycle bool `json:"-"` // the error is an import cycle
- Hard bool `json:"-"` // whether the error is soft or hard; soft errors are ignored in some places
+ Err error // the error itself
+ IsImportCycle bool // the error is an import cycle
+ Hard bool // whether the error is soft or hard; soft errors are ignored in some places
}
func (p *PackageError) Error() string {
@@ -317,12 +318,77 @@
if p.Pos != "" {
// Omit import stack. The full path to the file where the error
// is the most important thing.
- return p.Pos + ": " + p.Err
+ return p.Pos + ": " + p.Err.Error()
}
- if len(p.ImportStack) == 0 {
- return p.Err
+
+ // If the error is an ImportPathError, and the last path on the stack appears
+ // in the error message, omit that path from the stack to avoid repetition.
+ // If an ImportPathError wraps another ImportPathError that matches the
+ // last path on the stack, we don't omit the path. An error like
+ // "package A imports B: error loading C caused by B" would not be clearer
+ // if "imports B" were omitted.
+ stack := p.ImportStack
+ var ierr ImportPathError
+ if len(stack) > 0 && errors.As(p.Err, &ierr) && ierr.ImportPath() == stack[len(stack)-1] {
+ stack = stack[:len(stack)-1]
}
- return "package " + strings.Join(p.ImportStack, "\n\timports ") + ": " + p.Err
+ if len(stack) == 0 {
+ return p.Err.Error()
+ }
+ return "package " + strings.Join(stack, "\n\timports ") + ": " + p.Err.Error()
+}
+
+// PackageError implements MarshalJSON so that Err is marshaled as a string
+// and non-essential fields are omitted.
+func (p *PackageError) MarshalJSON() ([]byte, error) {
+ perr := struct {
+ ImportStack []string
+ Pos string
+ Err string
+ }{p.ImportStack, p.Pos, p.Err.Error()}
+ return json.Marshal(perr)
+}
+
+// ImportPathError is a type of error that prevents a package from being loaded
+// for a given import path. When such a package is loaded, a *Package is
+// returned with Err wrapping an ImportPathError: the error is attached to
+// the imported package, not the importing package.
+//
+// The string returned by ImportPath must appear in the string returned by
+// Error. Errors that wrap ImportPathError (such as PackageError) may omit
+// the import path.
+type ImportPathError interface {
+ error
+ ImportPath() string
+}
+
+type importError struct {
+ importPath string
+ err error // created with fmt.Errorf
+}
+
+var _ ImportPathError = (*importError)(nil)
+
+func ImportErrorf(path, format string, args ...interface{}) ImportPathError {
+ err := &importError{importPath: path, err: fmt.Errorf(format, args...)}
+ if errStr := err.Error(); !strings.Contains(errStr, path) {
+ panic(fmt.Sprintf("path %q not in error %q", path, errStr))
+ }
+ return err
+}
+
+func (e *importError) Error() string {
+ return e.err.Error()
+}
+
+func (e *importError) Unwrap() error {
+ // Don't return e.err directly, since we're only wrapping an error if %w
+ // was passed to ImportErrorf.
+ return errors.Unwrap(e.err)
+}
+
+func (e *importError) ImportPath() string {
+ return e.importPath
}
// An ImportStack is a stack of import paths, possibly with the suffix " (test)" appended.
@@ -489,7 +555,7 @@
ImportPath: path,
Error: &PackageError{
ImportStack: stk.Copy(),
- Err: err.Error(),
+ Err: err,
},
},
}
@@ -516,7 +582,7 @@
if !cfg.ModulesEnabled && path != cleanImport(path) {
p.Error = &PackageError{
ImportStack: stk.Copy(),
- Err: fmt.Sprintf("non-canonical import path: %q should be %q", path, pathpkg.Clean(path)),
+ Err: fmt.Errorf("non-canonical import path: %q should be %q", path, pathpkg.Clean(path)),
}
p.Incomplete = true
}
@@ -536,20 +602,22 @@
perr := *p
perr.Error = &PackageError{
ImportStack: stk.Copy(),
- Err: fmt.Sprintf("import %q is a program, not an importable package", path),
+ Err: ImportErrorf(path, "import %q is a program, not an importable package", path),
}
return setErrorPos(&perr, importPos)
}
if p.Internal.Local && parent != nil && !parent.Internal.Local {
perr := *p
- errMsg := fmt.Sprintf("local import %q in non-local package", path)
+ var err error
if path == "." {
- errMsg = "cannot import current directory"
+ err = ImportErrorf(path, "%s: cannot import current directory", path)
+ } else {
+ err = ImportErrorf(path, "local import %q in non-local package", path)
}
perr.Error = &PackageError{
ImportStack: stk.Copy(),
- Err: errMsg,
+ Err: err,
}
return setErrorPos(&perr, importPos)
}
@@ -1125,7 +1193,7 @@
if p.Error == nil {
p.Error = &PackageError{
ImportStack: stk.Copy(),
- Err: "import cycle not allowed",
+ Err: errors.New("import cycle not allowed"),
IsImportCycle: true,
}
}
@@ -1228,7 +1296,7 @@
perr := *p
perr.Error = &PackageError{
ImportStack: stk.Copy(),
- Err: "use of internal package " + p.ImportPath + " not allowed",
+ Err: ImportErrorf(p.ImportPath, "use of internal package "+p.ImportPath+" not allowed"),
}
perr.Incomplete = true
return &perr
@@ -1275,7 +1343,7 @@
perr := *p
perr.Error = &PackageError{
ImportStack: stk.Copy(),
- Err: "must be imported as " + path[i+len("vendor/"):],
+ Err: ImportErrorf(path, "%s must be imported as %s", path, path[i+len("vendor/"):]),
}
perr.Incomplete = true
return &perr
@@ -1329,7 +1397,7 @@
perr := *p
perr.Error = &PackageError{
ImportStack: stk.Copy(),
- Err: "use of vendored package not allowed",
+ Err: errors.New("use of vendored package not allowed"),
}
perr.Incomplete = true
return &perr
@@ -1455,7 +1523,7 @@
err = base.ExpandScanner(err)
p.Error = &PackageError{
ImportStack: stk.Copy(),
- Err: err.Error(),
+ Err: err,
}
return
}
@@ -1472,7 +1540,7 @@
// Report an error when the old code.google.com/p/go.tools paths are used.
if InstallTargetDir(p) == StalePath {
newPath := strings.Replace(p.ImportPath, "code.google.com/p/go.", "golang.org/x/", 1)
- e := fmt.Sprintf("the %v command has moved; use %v instead.", p.ImportPath, newPath)
+ e := ImportErrorf(p.ImportPath, "the %v command has moved; use %v instead.", p.ImportPath, newPath)
p.Error = &PackageError{Err: e}
return
}
@@ -1585,7 +1653,7 @@
if f1 != "" {
p.Error = &PackageError{
ImportStack: stk.Copy(),
- Err: fmt.Sprintf("case-insensitive file name collision: %q and %q", f1, f2),
+ Err: fmt.Errorf("case-insensitive file name collision: %q and %q", f1, f2),
}
return
}
@@ -1601,7 +1669,7 @@
if !SafeArg(file) || strings.HasPrefix(file, "_cgo_") {
p.Error = &PackageError{
ImportStack: stk.Copy(),
- Err: fmt.Sprintf("invalid input file name %q", file),
+ Err: fmt.Errorf("invalid input file name %q", file),
}
return
}
@@ -1609,14 +1677,14 @@
if name := pathpkg.Base(p.ImportPath); !SafeArg(name) {
p.Error = &PackageError{
ImportStack: stk.Copy(),
- Err: fmt.Sprintf("invalid input directory name %q", name),
+ Err: fmt.Errorf("invalid input directory name %q", name),
}
return
}
if !SafeArg(p.ImportPath) {
p.Error = &PackageError{
ImportStack: stk.Copy(),
- Err: fmt.Sprintf("invalid import path %q", p.ImportPath),
+ Err: ImportErrorf(p.ImportPath, "invalid import path %q", p.ImportPath),
}
return
}
@@ -1662,31 +1730,31 @@
// code; see issue #16050).
}
- setError := func(msg string) {
+ setError := func(err error) {
p.Error = &PackageError{
ImportStack: stk.Copy(),
- Err: msg,
+ Err: err,
}
}
// The gc toolchain only permits C source files with cgo or SWIG.
if len(p.CFiles) > 0 && !p.UsesCgo() && !p.UsesSwig() && cfg.BuildContext.Compiler == "gc" {
- setError(fmt.Sprintf("C source files not allowed when not using cgo or SWIG: %s", strings.Join(p.CFiles, " ")))
+ setError(fmt.Errorf("C source files not allowed when not using cgo or SWIG: %s", strings.Join(p.CFiles, " ")))
return
}
// C++, Objective-C, and Fortran source files are permitted only with cgo or SWIG,
// regardless of toolchain.
if len(p.CXXFiles) > 0 && !p.UsesCgo() && !p.UsesSwig() {
- setError(fmt.Sprintf("C++ source files not allowed when not using cgo or SWIG: %s", strings.Join(p.CXXFiles, " ")))
+ setError(fmt.Errorf("C++ source files not allowed when not using cgo or SWIG: %s", strings.Join(p.CXXFiles, " ")))
return
}
if len(p.MFiles) > 0 && !p.UsesCgo() && !p.UsesSwig() {
- setError(fmt.Sprintf("Objective-C source files not allowed when not using cgo or SWIG: %s", strings.Join(p.MFiles, " ")))
+ setError(fmt.Errorf("Objective-C source files not allowed when not using cgo or SWIG: %s", strings.Join(p.MFiles, " ")))
return
}
if len(p.FFiles) > 0 && !p.UsesCgo() && !p.UsesSwig() {
- setError(fmt.Sprintf("Fortran source files not allowed when not using cgo or SWIG: %s", strings.Join(p.FFiles, " ")))
+ setError(fmt.Errorf("Fortran source files not allowed when not using cgo or SWIG: %s", strings.Join(p.FFiles, " ")))
return
}
@@ -1695,7 +1763,7 @@
if other := foldPath[fold]; other == "" {
foldPath[fold] = p.ImportPath
} else if other != p.ImportPath {
- setError(fmt.Sprintf("case-insensitive import collision: %q and %q", p.ImportPath, other))
+ setError(ImportErrorf(p.ImportPath, "case-insensitive import collision: %q and %q", p.ImportPath, other))
return
}
@@ -2102,7 +2170,7 @@
pkg.Internal.CmdlineFiles = true
pkg.Name = f
pkg.Error = &PackageError{
- Err: fmt.Sprintf("named files must be .go files: %s", pkg.Name),
+ Err: fmt.Errorf("named files must be .go files: %s", pkg.Name),
}
return pkg
}
diff --git a/src/cmd/go/internal/load/test.go b/src/cmd/go/internal/load/test.go
index aac7d7d..fefc7d2 100644
--- a/src/cmd/go/internal/load/test.go
+++ b/src/cmd/go/internal/load/test.go
@@ -110,7 +110,7 @@
// non-test copy of a package.
ptestErr = &PackageError{
ImportStack: testImportStack(stk[0], p1, p.ImportPath),
- Err: "import cycle not allowed in test",
+ Err: errors.New("import cycle not allowed in test"),
IsImportCycle: true,
}
}
@@ -271,7 +271,7 @@
// afterward that gathers t.Cover information.
t, err := loadTestFuncs(ptest)
if err != nil && pmain.Error == nil {
- pmain.Error = &PackageError{Err: err.Error()}
+ pmain.Error = &PackageError{Err: err}
}
t.Cover = cover
if len(ptest.GoFiles)+len(ptest.CgoFiles) > 0 {
@@ -322,7 +322,7 @@
data, err := formatTestmain(t)
if err != nil && pmain.Error == nil {
- pmain.Error = &PackageError{Err: err.Error()}
+ pmain.Error = &PackageError{Err: err}
}
if data != nil {
pmain.Internal.TestmainGo = &data
diff --git a/src/cmd/go/internal/modload/import.go b/src/cmd/go/internal/modload/import.go
index 8d6f789..5b1f0ce 100644
--- a/src/cmd/go/internal/modload/import.go
+++ b/src/cmd/go/internal/modload/import.go
@@ -16,6 +16,7 @@
"time"
"cmd/go/internal/cfg"
+ "cmd/go/internal/load"
"cmd/go/internal/modfetch"
"cmd/go/internal/module"
"cmd/go/internal/par"
@@ -25,32 +26,38 @@
)
type ImportMissingError struct {
- ImportPath string
- Module module.Version
- QueryErr error
+ Path string
+ Module module.Version
+ QueryErr error
// newMissingVersion is set to a newer version of Module if one is present
// in the build list. When set, we can't automatically upgrade.
newMissingVersion string
}
+var _ load.ImportPathError = (*ImportMissingError)(nil)
+
func (e *ImportMissingError) Error() string {
if e.Module.Path == "" {
- if str.HasPathPrefix(e.ImportPath, "cmd") {
- return fmt.Sprintf("package %s is not in GOROOT (%s)", e.ImportPath, filepath.Join(cfg.GOROOT, "src", e.ImportPath))
+ if str.HasPathPrefix(e.Path, "cmd") {
+ return fmt.Sprintf("package %s is not in GOROOT (%s)", e.Path, filepath.Join(cfg.GOROOT, "src", e.Path))
}
if e.QueryErr != nil {
- return fmt.Sprintf("cannot find module providing package %s: %v", e.ImportPath, e.QueryErr)
+ return fmt.Sprintf("cannot find module providing package %s: %v", e.Path, e.QueryErr)
}
- return "cannot find module providing package " + e.ImportPath
+ return "cannot find module providing package " + e.Path
}
- return fmt.Sprintf("missing module for import: %s@%s provides %s", e.Module.Path, e.Module.Version, e.ImportPath)
+ return fmt.Sprintf("missing module for import: %s@%s provides %s", e.Module.Path, e.Module.Version, e.Path)
}
func (e *ImportMissingError) Unwrap() error {
return e.QueryErr
}
+func (e *ImportMissingError) ImportPath() string {
+ return e.Path
+}
+
// An AmbiguousImportError indicates an import of a package found in multiple
// modules in the build list, or found in both the main module and its vendor
// directory.
@@ -121,7 +128,7 @@
return module.Version{}, dir, nil
}
if str.HasPathPrefix(path, "cmd") {
- return module.Version{}, "", &ImportMissingError{ImportPath: path}
+ return module.Version{}, "", &ImportMissingError{Path: path}
}
// -mod=vendor is special.
@@ -220,7 +227,7 @@
}
_, ok := dirInModule(path, m.Path, root, isLocal)
if ok {
- return m, "", &ImportMissingError{ImportPath: path, Module: m}
+ return m, "", &ImportMissingError{Path: path, Module: m}
}
}
}
@@ -230,7 +237,7 @@
if errors.Is(err, os.ErrNotExist) {
// Return "cannot find module providing package […]" instead of whatever
// low-level error QueryPackage produced.
- return module.Version{}, "", &ImportMissingError{ImportPath: path, QueryErr: err}
+ return module.Version{}, "", &ImportMissingError{Path: path, QueryErr: err}
} else {
return module.Version{}, "", err
}
@@ -255,7 +262,7 @@
}
}
}
- return m, "", &ImportMissingError{ImportPath: path, Module: m, newMissingVersion: newMissingVersion}
+ return m, "", &ImportMissingError{Path: path, Module: m, newMissingVersion: newMissingVersion}
}
// maybeInModule reports whether, syntactically,
diff --git a/src/cmd/go/internal/work/exec.go b/src/cmd/go/internal/work/exec.go
index b75c61b..68ab85a 100644
--- a/src/cmd/go/internal/work/exec.go
+++ b/src/cmd/go/internal/work/exec.go
@@ -433,7 +433,7 @@
err = fmt.Errorf("go build %s: %v", a.Package.ImportPath, err)
}
if err != nil && b.IsCmdList && b.NeedError && p.Error == nil {
- p.Error = &load.PackageError{Err: err.Error()}
+ p.Error = &load.PackageError{Err: err}
}
}()
if cfg.BuildN {
diff --git a/src/cmd/go/testdata/script/cmd_import_error.txt b/src/cmd/go/testdata/script/cmd_import_error.txt
index ba94f9b..685c606 100644
--- a/src/cmd/go/testdata/script/cmd_import_error.txt
+++ b/src/cmd/go/testdata/script/cmd_import_error.txt
@@ -5,7 +5,7 @@
# a clear error in module mode.
! go list cmd/unknown
-stderr '^can''t load package: package cmd/unknown: package cmd/unknown is not in GOROOT \('$GOROOT'[/\\]src[/\\]cmd[/\\]unknown\)$'
+stderr '^can''t load package: package cmd/unknown is not in GOROOT \('$GOROOT'[/\\]src[/\\]cmd[/\\]unknown\)$'
go list -f '{{range .DepsErrors}}{{.Err}}{{end}}' x.go
stdout '^package cmd/unknown is not in GOROOT \('$GOROOT'[/\\]src[/\\]cmd[/\\]unknown\)$'
diff --git a/src/go/build/build.go b/src/go/build/build.go
index 097ad3c..526d2fe 100644
--- a/src/go/build/build.go
+++ b/src/go/build/build.go
@@ -1046,7 +1046,7 @@
parent = d
}
- cmd := exec.Command("go", "list", "-compiler="+ctxt.Compiler, "-tags="+strings.Join(ctxt.BuildTags, ","), "-installsuffix="+ctxt.InstallSuffix, "-f={{.Dir}}\n{{.ImportPath}}\n{{.Root}}\n{{.Goroot}}\n", path)
+ cmd := exec.Command("go", "list", "-e", "-compiler="+ctxt.Compiler, "-tags="+strings.Join(ctxt.BuildTags, ","), "-installsuffix="+ctxt.InstallSuffix, "-f={{.Dir}}\n{{.ImportPath}}\n{{.Root}}\n{{.Goroot}}\n{{if .Error}}{{.Error}}{{end}}\n", "--", path)
// TODO(bcmills): This is wrong if srcDir is in a vendor directory, or if
// srcDir is in some module dependency of the main module. The main module
@@ -1073,12 +1073,22 @@
return fmt.Errorf("go/build: importGo %s: %v\n%s\n", path, err, stderr.String())
}
- f := strings.Split(stdout.String(), "\n")
- if len(f) != 5 || f[4] != "" {
+ f := strings.SplitN(stdout.String(), "\n", 5)
+ if len(f) != 5 {
return fmt.Errorf("go/build: importGo %s: unexpected output:\n%s\n", path, stdout.String())
}
+ dir := f[0]
+ errStr := strings.TrimSpace(f[4])
+ if errStr != "" && p.Dir == "" {
+ // If 'go list' could not locate the package, return the same error that
+ // 'go list' reported.
+ // If 'go list' did locate the package (p.Dir is not empty), ignore the
+ // error. It was probably related to loading source files, and we'll
+ // encounter it ourselves shortly.
+ return errors.New(errStr)
+ }
- p.Dir = f[0]
+ p.Dir = dir
p.ImportPath = f[1]
p.Root = f[2]
p.Goroot = f[3] == "true"
diff --git a/src/go/build/build_test.go b/src/go/build/build_test.go
index cff091f..47a46f8 100644
--- a/src/go/build/build_test.go
+++ b/src/go/build/build_test.go
@@ -7,6 +7,7 @@
import (
"internal/testenv"
"io"
+ "io/ioutil"
"os"
"path/filepath"
"reflect"
@@ -447,3 +448,29 @@
t.Fatalf("incorrectly set .Doc to %q", p.Doc)
}
}
+
+// TestMissingImportErrorRepetition checks that when an unknown package is
+// imported, the package path is only shown once in the error.
+// Verifies golang.org/issue/34752.
+func TestMissingImportErrorRepetition(t *testing.T) {
+ testenv.MustHaveGoBuild(t) // need 'go list' internally
+ tmp, err := ioutil.TempDir("", "")
+ if err != nil {
+ t.Fatal(err)
+ }
+ defer os.RemoveAll(tmp)
+ if err := ioutil.WriteFile(filepath.Join(tmp, "go.mod"), []byte("module m"), 0666); err != nil {
+ t.Fatal(err)
+ }
+ defer os.Setenv("GO111MODULE", os.Getenv("GO111MODULE"))
+ os.Setenv("GO111MODULE", "on")
+ defer os.Setenv("GOPROXY", os.Getenv("GOPROXY"))
+ os.Setenv("GOPROXY", "off")
+
+ pkgPath := "example.com/hello"
+ if _, err = Import(pkgPath, tmp, FindOnly); err == nil {
+ t.Fatal("unexpected success")
+ } else if n := strings.Count(err.Error(), pkgPath); n != 1 {
+ t.Fatalf("package path %q appears in error %d times; should appear once\nerror: %v", pkgPath, n, err)
+ }
+}
