8 files changed, 33 insertions, 21 deletions
diff --git a/src/cmd/go/internal/envcmd/env.go b/src/cmd/go/internal/envcmd/env.go
index c1adf8cef4c..2a283fc4f80 100644
--- a/src/cmd/go/internal/envcmd/env.go
+++ b/src/cmd/go/internal/envcmd/env.go
@@ -167,8 +167,8 @@ func ExtraEnvVars() []cfg.EnvVar {
 // ExtraEnvVarsCostly returns environment variables that should not leak into child processes
 // but are costly to evaluate.
 func ExtraEnvVarsCostly() []cfg.EnvVar {
-	var b work.Builder
-	b.Init()
+	b := work.NewBuilder("")
+
 	cppflags, cflags, cxxflags, fflags, ldflags, err := b.CFlags(&load.Package{})
 	if err != nil {
 		// Should not happen - b.CFlags was given an empty package.
diff --git a/src/cmd/go/internal/list/list.go b/src/cmd/go/internal/list/list.go
index 62c18866c4c..c15749ebf19 100644
--- a/src/cmd/go/internal/list/list.go
+++ b/src/cmd/go/internal/list/list.go
@@ -592,8 +592,7 @@ func runList(ctx context.Context, cmd *base.Command, args []string) {
 	// Do we need to run a build to gather information?
 	needStale := *listJson || strings.Contains(*listFmt, ".Stale")
 	if needStale || *listExport || *listCompiled {
-		var b work.Builder
-		b.Init()
+		b := work.NewBuilder("")
 		b.IsCmdList = true
 		b.NeedExport = *listExport
 		b.NeedCompiledGoFiles = *listCompiled
diff --git a/src/cmd/go/internal/run/run.go b/src/cmd/go/internal/run/run.go
index 312b49ef5df..a0aca316fcf 100644
--- a/src/cmd/go/internal/run/run.go
+++ b/src/cmd/go/internal/run/run.go
@@ -87,8 +87,7 @@ func runRun(ctx context.Context, cmd *base.Command, args []string) {
 	}
 
 	work.BuildInit()
-	var b work.Builder
-	b.Init()
+	b := work.NewBuilder("")
 	b.Print = printStderr
 
 	i := 0
diff --git a/src/cmd/go/internal/test/test.go b/src/cmd/go/internal/test/test.go
index 50e6d5201b0..3f31a8a80d5 100644
--- a/src/cmd/go/internal/test/test.go
+++ b/src/cmd/go/internal/test/test.go
@@ -744,8 +744,7 @@ func runTest(ctx context.Context, cmd *base.Command, args []string) {
 		}
 	}
 
-	var b work.Builder
-	b.Init()
+	b := work.NewBuilder("")
 
 	if cfg.BuildI {
 		fmt.Fprint(os.Stderr, "go: -i flag is deprecated\n")
@@ -800,7 +799,16 @@ func runTest(ctx context.Context, cmd *base.Command, args []string) {
 		if !testC || a.Failed {
 			return
 		}
-		b.Init()
+
+		// TODO(bcmills): I have no idea why the Builder must be reset here, but
+		// without this reset dance, TestGoTestDashIDashOWritesBinary fails with
+		// lots of "vet config not found" errors. This was added in CL 5699088,
+		// which had almost no public discussion, a very short commit description,
+		// and left no comment in the code to explain what is going on here. 🤯
+		//
+		// Maybe this has the effect of removing actions that were registered by the
+		// call to CompileAction above?
+		b = work.NewBuilder("")
 	}
 
 	var builds, runs, prints []*work.Action
@@ -916,7 +924,7 @@ func runTest(ctx context.Context, cmd *base.Command, args []string) {
 			ensureImport(p, "sync/atomic")
 		}
 
-		buildTest, runTest, printTest, err := builderTest(&b, ctx, pkgOpts, p, allImports[p])
+		buildTest, runTest, printTest, err := builderTest(b, ctx, pkgOpts, p, allImports[p])
 		if err != nil {
 			str := err.Error()
 			str = strings.TrimPrefix(str, "\n")
diff --git a/src/cmd/go/internal/vet/vet.go b/src/cmd/go/internal/vet/vet.go
index d3e0dd8116f..9b8698295af 100644
--- a/src/cmd/go/internal/vet/vet.go
+++ b/src/cmd/go/internal/vet/vet.go
@@ -94,8 +94,7 @@ func runVet(ctx context.Context, cmd *base.Command, args []string) {
 		base.Fatalf("no packages to vet")
 	}
 
-	var b work.Builder
-	b.Init()
+	b := work.NewBuilder("")
 
 	root := &work.Action{Mode: "go vet"}
 	for _, p := range pkgs {
diff --git a/src/cmd/go/internal/work/action.go b/src/cmd/go/internal/work/action.go
index c0862c5efe5..4bbd23ab8e4 100644
--- a/src/cmd/go/internal/work/action.go
+++ b/src/cmd/go/internal/work/action.go
@@ -240,7 +240,13 @@ const (
 	ModeVetOnly = 1 << 8
 )
 
-func (b *Builder) Init() {
+// NewBuilder returns a new Builder ready for use.
+//
+// If workDir is the empty string, NewBuilder creates a WorkDir if needed
+// and arranges for it to be removed in case of an unclean exit.
+func NewBuilder(workDir string) *Builder {
+	b := new(Builder)
+
 	b.Print = func(a ...any) (int, error) {
 		return fmt.Fprint(os.Stderr, a...)
 	}
@@ -249,7 +255,9 @@ func (b *Builder) Init() {
 	b.toolIDCache = make(map[string]string)
 	b.buildIDCache = make(map[string]string)
 
-	if cfg.BuildN {
+	if workDir != "" {
+		b.WorkDir = workDir
+	} else if cfg.BuildN {
 		b.WorkDir = "$WORK"
 	} else {
 		tmp, err := os.MkdirTemp(cfg.Getenv("GOTMPDIR"), "go-build")
@@ -306,6 +314,8 @@ func (b *Builder) Init() {
 			base.Exit()
 		}
 	}
+
+	return b
 }
 
 func CheckGOOSARCHPair(goos, goarch string) error {
diff --git a/src/cmd/go/internal/work/build.go b/src/cmd/go/internal/work/build.go
index 394fe910500..e66dad68981 100644
--- a/src/cmd/go/internal/work/build.go
+++ b/src/cmd/go/internal/work/build.go
@@ -402,8 +402,7 @@ var runtimeVersion = runtime.Version()
 func runBuild(ctx context.Context, cmd *base.Command, args []string) {
 	modload.InitWorkfile()
 	BuildInit()
-	var b Builder
-	b.Init()
+	b := NewBuilder("")
 
 	pkgs := load.PackagesAndErrors(ctx, load.PackageOpts{LoadVCS: true}, args)
 	load.CheckPackageErrors(pkgs)
@@ -721,8 +720,8 @@ func InstallPackages(ctx context.Context, patterns []string, pkgs []*load.Packag
 	}
 	base.ExitIfErrors()
 
-	var b Builder
-	b.Init()
+	b := NewBuilder("")
+
 	depMode := ModeBuild
 	if cfg.BuildI {
 		depMode = ModeInstall
diff --git a/src/cmd/go/script_test.go b/src/cmd/go/script_test.go
index 55a88e0e0b0..aac0b4792da 100644
--- a/src/cmd/go/script_test.go
+++ b/src/cmd/go/script_test.go
@@ -532,10 +532,8 @@ func (ts *testScript) cmdCc(want simpleStatus, args []string) {
 		ts.fatalf("usage: cc args... [&]")
 	}
 
-	var b work.Builder
-	b.Init()
+	b := work.NewBuilder(ts.workdir)
 	ts.cmdExec(want, append(b.GccCmd(".", ""), args...))
-	robustio.RemoveAll(b.WorkDir)
 }
 
 // cd changes to a different directory.