cmd/go: propagate context into Action.Func calls

Action.Func is now a func(*Builder, context.Context, *Action), so that
contexts can be propagated into the action funcs. While context
is traditionally the first parameter of a function, it's the second
parameter of Action.Func's type to continue to allow for methods
on Builder to be used as functions taking a *Builder as the first
parameter. context.Context is instead the first parameter on
those functions.

Change-Id: I5f058d6a99a1e96fe2025f2e8ce30a033d12e935
Reviewed-on: https://go-review.googlesource.com/c/go/+/248321
Run-TryBot: Michael Matloob <matloob@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Bryan C. Mills <bcmills@google.com>
diff --git a/src/cmd/go/internal/run/run.go b/src/cmd/go/internal/run/run.go
index 3630f68..deec510 100644
--- a/src/cmd/go/internal/run/run.go
+++ b/src/cmd/go/internal/run/run.go
@@ -146,7 +146,7 @@
 
 // buildRunProgram is the action for running a binary that has already
 // been compiled. We ignore exit status.
-func buildRunProgram(b *work.Builder, a *work.Action) error {
+func buildRunProgram(b *work.Builder, ctx context.Context, a *work.Action) error {
 	cmdline := str.StringList(work.FindExecCmd(), a.Deps[0].Target, a.Args)
 	if cfg.BuildN || cfg.BuildX {
 		b.Showcmd("", "%s", strings.Join(cmdline, " "))
diff --git a/src/cmd/go/internal/test/test.go b/src/cmd/go/internal/test/test.go
index d71d339..9788590 100644
--- a/src/cmd/go/internal/test/test.go
+++ b/src/cmd/go/internal/test/test.go
@@ -1069,7 +1069,7 @@
 }
 
 // builderRunTest is the action for running a test binary.
-func (c *runCache) builderRunTest(b *work.Builder, a *work.Action) error {
+func (c *runCache) builderRunTest(b *work.Builder, ctx context.Context, a *work.Action) error {
 	if a.Failed {
 		// We were unable to build the binary.
 		a.Failed = false
@@ -1642,7 +1642,7 @@
 }
 
 // builderCleanTest is the action for cleaning up after a test.
-func builderCleanTest(b *work.Builder, a *work.Action) error {
+func builderCleanTest(b *work.Builder, ctx context.Context, a *work.Action) error {
 	if cfg.BuildWork {
 		return nil
 	}
@@ -1654,7 +1654,7 @@
 }
 
 // builderPrintTest is the action for printing a test result.
-func builderPrintTest(b *work.Builder, a *work.Action) error {
+func builderPrintTest(b *work.Builder, ctx context.Context, a *work.Action) error {
 	clean := a.Deps[0]
 	run := clean.Deps[0]
 	if run.TestOutput != nil {
@@ -1665,7 +1665,7 @@
 }
 
 // builderNoTest is the action for testing a package with no test files.
-func builderNoTest(b *work.Builder, a *work.Action) error {
+func builderNoTest(b *work.Builder, ctx context.Context, a *work.Action) error {
 	var stdout io.Writer = os.Stdout
 	if testJSON {
 		json := test2json.NewConverter(lockedStdout{}, a.Package.ImportPath, test2json.Timestamp)
@@ -1677,7 +1677,7 @@
 }
 
 // printExitStatus is the action for printing the exit status
-func printExitStatus(b *work.Builder, a *work.Action) error {
+func printExitStatus(b *work.Builder, ctx context.Context, a *work.Action) error {
 	if !testJSON && len(pkgArgs) != 0 {
 		if base.GetExitStatus() != 0 {
 			fmt.Println("FAIL")
diff --git a/src/cmd/go/internal/work/action.go b/src/cmd/go/internal/work/action.go
index 6b5f9e4..a37a5e6 100644
--- a/src/cmd/go/internal/work/action.go
+++ b/src/cmd/go/internal/work/action.go
@@ -10,6 +10,7 @@
 	"bufio"
 	"bytes"
 	"container/heap"
+	"context"
 	"debug/elf"
 	"encoding/json"
 	"fmt"
@@ -63,13 +64,13 @@
 
 // An Action represents a single action in the action graph.
 type Action struct {
-	Mode       string                        // description of action operation
-	Package    *load.Package                 // the package this action works on
-	Deps       []*Action                     // actions that must happen before this one
-	Func       func(*Builder, *Action) error // the action itself (nil = no-op)
-	IgnoreFail bool                          // whether to run f even if dependencies fail
-	TestOutput *bytes.Buffer                 // test output buffer
-	Args       []string                      // additional args for runProgram
+	Mode       string                                         // description of action operation
+	Package    *load.Package                                  // the package this action works on
+	Deps       []*Action                                      // actions that must happen before this one
+	Func       func(*Builder, context.Context, *Action) error // the action itself (nil = no-op)
+	IgnoreFail bool                                           // whether to run f even if dependencies fail
+	TestOutput *bytes.Buffer                                  // test output buffer
+	Args       []string                                       // additional args for runProgram
 
 	triggers []*Action // inverse of deps
 
diff --git a/src/cmd/go/internal/work/exec.go b/src/cmd/go/internal/work/exec.go
index 56a127f..3903502 100644
--- a/src/cmd/go/internal/work/exec.go
+++ b/src/cmd/go/internal/work/exec.go
@@ -127,8 +127,7 @@
 				desc += "(" + a.Mode + " " + a.Package.Desc() + ")"
 			}
 			ctx, span := trace.StartSpan(ctx, desc)
-			_ = ctx
-			err = a.Func(b, a)
+			err = a.Func(b, ctx, a)
 			span.Done()
 		}
 		if a.json != nil {
@@ -400,7 +399,7 @@
 
 // build is the action for building a single package.
 // Note that any new influence on this logic must be reported in b.buildActionID above as well.
-func (b *Builder) build(a *Action) (err error) {
+func (b *Builder) build(ctx context.Context, a *Action) (err error) {
 	p := a.Package
 
 	bit := func(x uint32, b bool) uint32 {
@@ -1005,7 +1004,7 @@
 // VetExplicit records whether the vet flags were set explicitly on the command line.
 var VetExplicit bool
 
-func (b *Builder) vet(a *Action) error {
+func (b *Builder) vet(ctx context.Context, a *Action) error {
 	// a.Deps[0] is the build of the package being vetted.
 	// a.Deps[1] is the build of the "fmt" package.
 
@@ -1196,7 +1195,7 @@
 
 // link is the action for linking a single command.
 // Note that any new influence on this logic must be reported in b.linkActionID above as well.
-func (b *Builder) link(a *Action) (err error) {
+func (b *Builder) link(ctx context.Context, a *Action) (err error) {
 	if b.useCache(a, b.linkActionID(a), a.Package.Target) || b.IsCmdList {
 		return nil
 	}
@@ -1388,7 +1387,7 @@
 	return
 }
 
-func (b *Builder) installShlibname(a *Action) error {
+func (b *Builder) installShlibname(ctx context.Context, a *Action) error {
 	if err := allowInstall(a); err != nil {
 		return err
 	}
@@ -1437,7 +1436,7 @@
 	return h.Sum()
 }
 
-func (b *Builder) linkShared(a *Action) (err error) {
+func (b *Builder) linkShared(ctx context.Context, a *Action) (err error) {
 	if b.useCache(a, b.linkSharedActionID(a), a.Target) || b.IsCmdList {
 		return nil
 	}
@@ -1463,7 +1462,7 @@
 }
 
 // BuildInstallFunc is the action for installing a single package or executable.
-func BuildInstallFunc(b *Builder, a *Action) (err error) {
+func BuildInstallFunc(b *Builder, ctx context.Context, a *Action) (err error) {
 	defer func() {
 		if err != nil && err != errPrintedOutput {
 			// a.Package == nil is possible for the go install -buildmode=shared
@@ -1716,7 +1715,7 @@
 }
 
 // Install the cgo export header file, if there is one.
-func (b *Builder) installHeader(a *Action) error {
+func (b *Builder) installHeader(ctx context.Context, a *Action) error {
 	src := a.Objdir + "_cgo_install.h"
 	if _, err := os.Stat(src); os.IsNotExist(err) {
 		// If the file does not exist, there are no exported