cmd/go: inject State parameter into toolchain.Select

This command modifies the call tree starting at `toolchain.Select` to
inject a `State` parameter to every function that is currently using
the global `modload.LoaderState` variable.  By explicilty passing a
`State` parameter, we can begin to eliminate the usage of the global
`modload.LoaderState`.

This commit is part of the overall effort to eliminate global
modloader state.

[git-generate]
cd src/cmd/go/internal/toolchain
rf '
  inject modload.LoaderState Select
  add select.go var moduleLoaderState *modload.State
  ex {
    import "cmd/go/internal/modload";
    modload.LoaderState -> moduleLoaderState
  }
  add Select://+0 moduleLoaderState := modload.NewState()
  rm select.go:/var moduleLoaderState \*modload.State/
'
cd ..
./rf-cleanup.zsh

Change-Id: I759439a47e2b1aaa01a0a800bc18596dd7ce4983
Reviewed-on: https://go-review.googlesource.com/c/go/+/709988
Reviewed-by: Michael Matloob <matloob@google.com>
Reviewed-by: Michael Matloob <matloob@golang.org>
LUCI-TryBot-Result: Go LUCI <golang-scoped@luci-project-accounts.iam.gserviceaccount.com>

src/cmd/go/internal/modcmd/download.go

@@ -158,7 +158,7 @@ func runDownload(ctx context.Context, cmd *base.Command, args []string) {
 					// TODO(#64008): call base.Fatalf instead of toolchain.SwitchOrFatal
 					// here, since we can only reach this point with an outdated toolchain
 					// if the go.mod file is inconsistent.
-					toolchain.SwitchOrFatal(ctx, err)
+					toolchain.SwitchOrFatal(modload.LoaderState, ctx, err)
 				}
 
 				for _, m := range modFile.Require {

src/cmd/go/internal/modcmd/graph.go

@@ -62,7 +62,7 @@ func runGraph(ctx context.Context, cmd *base.Command, args []string) {
 
 	goVersion := graphGo.String()
 	if goVersion != "" && gover.Compare(gover.Local(), goVersion) < 0 {
-		toolchain.SwitchOrFatal(ctx, &gover.TooNewError{
+		toolchain.SwitchOrFatal(modload.LoaderState, ctx, &gover.TooNewError{
 			What:      "-go flag",
 			GoVersion: goVersion,
 		})

src/cmd/go/internal/modcmd/tidy.go

@@ -124,7 +124,7 @@ func runTidy(ctx context.Context, cmd *base.Command, args []string) {
 
 	goVersion := tidyGo.String()
 	if goVersion != "" && gover.Compare(gover.Local(), goVersion) < 0 {
-		toolchain.SwitchOrFatal(ctx, &gover.TooNewError{
+		toolchain.SwitchOrFatal(modload.LoaderState, ctx, &gover.TooNewError{
 			What:      "-go flag",
 			GoVersion: goVersion,
 		})

src/cmd/go/internal/modget/get.go

@@ -418,7 +418,7 @@ func runGet(ctx context.Context, cmd *base.Command, args []string) {
 		// but the command line is not.
 		// TODO(bcmills): modload.EditBuildList should catch this instead,
 		// and then this can be changed to base.Fatal(err).
-		toolchain.SwitchOrFatal(ctx, err)
+		toolchain.SwitchOrFatal(modload.LoaderState, ctx, err)
 	}
 
 	newReqs := reqsFromGoMod(modload.ModFile())
@@ -558,7 +558,7 @@ func newResolver(ctx context.Context, queries []*query) *resolver {
 	// methods.
 	mg, err := modload.LoadModGraph(ctx, "")
 	if err != nil {
-		toolchain.SwitchOrFatal(ctx, err)
+		toolchain.SwitchOrFatal(modload.LoaderState, ctx, err)
 	}
 
 	buildList := mg.BuildList()
@@ -1619,7 +1619,7 @@ func (r *resolver) checkPackageProblems(ctx context.Context, pkgPatterns []strin
 			// are old enough but the go command itself is not new
 			// enough. See the related comment on the SwitchOrFatal
 			// in runGet when WriteGoMod returns an error.
-			toolchain.SwitchOrFatal(ctx, err)
+			toolchain.SwitchOrFatal(modload.LoaderState, ctx, err)
 		}
 	}
 
@@ -1989,7 +1989,7 @@ func (r *resolver) updateBuildList(ctx context.Context, additions []module.Versi
 	changed, err := modload.EditBuildList(modload.LoaderState, ctx, additions, resolved)
 	if err != nil {
 		if errors.Is(err, gover.ErrTooNew) {
-			toolchain.SwitchOrFatal(ctx, err)
+			toolchain.SwitchOrFatal(modload.LoaderState, ctx, err)
 		}
 
 		constraint, ok := errors.AsType[*modload.ConstraintError](err)
@@ -2035,7 +2035,7 @@ func (r *resolver) updateBuildList(ctx context.Context, additions []module.Versi
 
 	mg, err := modload.LoadModGraph(ctx, "")
 	if err != nil {
-		toolchain.SwitchOrFatal(ctx, err)
+		toolchain.SwitchOrFatal(modload.LoaderState, ctx, err)
 	}
 
 	r.buildList = mg.BuildList()

src/cmd/go/internal/modload/init.go

@@ -570,12 +570,12 @@ func Init(loaderstate *State) {
 // of 'go get', but Init reads the -modfile flag in 'go get', so it shouldn't
 // be called until the command is installed and flags are parsed. Instead of
 // calling Init and Enabled, the main package can call this function.
-func WillBeEnabled() bool {
+func WillBeEnabled(loaderstate *State) bool {
-	if LoaderState.modRoots != nil || cfg.ModulesEnabled {
+	if loaderstate.modRoots != nil || cfg.ModulesEnabled {
 		// Already enabled.
 		return true
 	}
-	if LoaderState.initialized {
+	if loaderstate.initialized {
 		// Initialized, not enabled.
 		return false
 	}

src/cmd/go/internal/telemetrystats/telemetrystats.go

@@ -22,7 +22,7 @@ func Increment() {
 // incrementConfig increments counters for the configuration
 // the command is running in.
 func incrementConfig() {
-	if !modload.WillBeEnabled() {
+	if !modload.WillBeEnabled(modload.LoaderState) {
 		counter.Inc("go/mode:gopath")
 	} else if workfile := modload.FindGoWork(modload.LoaderState, base.Cwd()); workfile != "" {
 		counter.Inc("go/mode:workspace")

src/cmd/go/internal/toolchain/select.go

@@ -95,10 +95,11 @@ var toolchainTrace = godebug.New("#toolchaintrace").Value() == "1"
 // It must be called early in startup.
 // See https://go.dev/doc/toolchain#select.
 func Select() {
+	moduleLoaderState := modload.NewState()
 	log.SetPrefix("go: ")
 	defer log.SetPrefix("")
 
-	if !modload.WillBeEnabled() {
+	if !modload.WillBeEnabled(moduleLoaderState) {
 		return
 	}
 
@@ -171,7 +172,7 @@ func Select() {
 	gotoolchain = minToolchain
 	if mode == "auto" || mode == "path" {
 		// Read go.mod to find new minimum and suggested toolchain.
-		file, goVers, toolchain := modGoToolchain()
+		file, goVers, toolchain := modGoToolchain(moduleLoaderState)
 		gover.Startup.AutoFile = file
 		if toolchain == "default" {
 			// "default" means always use the default toolchain,
@@ -231,7 +232,7 @@ func Select() {
 				}
 			}
 		}
-		maybeSwitchForGoInstallVersion(minVers)
+		maybeSwitchForGoInstallVersion(moduleLoaderState, minVers)
 	}
 
 	// If we are invoked as a target toolchain, confirm that
@@ -283,7 +284,7 @@ func Select() {
 	}
 
 	counterSelectExec.Inc()
-	Exec(modload.LoaderState, gotoolchain)
+	Exec(moduleLoaderState, gotoolchain)
 }
 
 var counterSelectExec = counter.New("go/toolchain/select-exec")
@@ -527,9 +528,9 @@ func raceSafeCopy(old, new string) error {
 // modGoToolchain finds the enclosing go.work or go.mod file
 // and returns the go version and toolchain lines from the file.
 // The toolchain line overrides the version line
-func modGoToolchain() (file, goVers, toolchain string) {
+func modGoToolchain(loaderstate *modload.State) (file, goVers, toolchain string) {
 	wd := base.UncachedCwd()
-	file = modload.FindGoWork(modload.LoaderState, wd)
+	file = modload.FindGoWork(loaderstate, wd)
 	// $GOWORK can be set to a file that does not yet exist, if we are running 'go work init'.
 	// Do not try to load the file in that case
 	if _, err := os.Stat(file); err != nil {
@@ -551,7 +552,7 @@ func modGoToolchain() (file, goVers, toolchain string) {
 
 // maybeSwitchForGoInstallVersion reports whether the command line is go install m@v or go run m@v.
 // If so, switch to the go version required to build m@v if it's higher than minVers.
-func maybeSwitchForGoInstallVersion(minVers string) {
+func maybeSwitchForGoInstallVersion(loaderstate *modload.State, minVers string) {
 	// Note: We assume there are no flags between 'go' and 'install' or 'run'.
 	// During testing there are some debugging flags that are accepted
 	// in that position, but in production go binaries there are not.
@@ -692,10 +693,10 @@ func maybeSwitchForGoInstallVersion(minVers string) {
 	// command lines if we add new flags in the future.
 
 	// Set up modules without an explicit go.mod, to download go.mod.
-	modload.LoaderState.ForceUseModules = true
+	loaderstate.ForceUseModules = true
-	modload.LoaderState.RootMode = modload.NoRoot
+	loaderstate.RootMode = modload.NoRoot
-	modload.Init(modload.LoaderState)
+	modload.Init(loaderstate)
-	defer modload.LoaderState.Reset()
+	defer loaderstate.Reset()
 
 	// See internal/load.PackagesAndErrorsOutsideModule
 	ctx := context.Background()
@@ -705,14 +706,14 @@ func maybeSwitchForGoInstallVersion(minVers string) {
 		allowed = nil
 	}
 	noneSelected := func(path string) (version string) { return "none" }
-	_, err := modload.QueryPackages(modload.LoaderState, ctx, path, version, noneSelected, allowed)
+	_, err := modload.QueryPackages(loaderstate, ctx, path, version, noneSelected, allowed)
 	if errors.Is(err, gover.ErrTooNew) {
 		// Run early switch, same one go install or go run would eventually do,
 		// if it understood all the command-line flags.
-		s := NewSwitcher(modload.LoaderState)
+		s := NewSwitcher(loaderstate)
 		s.Error(err)
 		if s.TooNew != nil && gover.Compare(s.TooNew.GoVersion, minVers) > 0 {
-			SwitchOrFatal(ctx, err)
+			SwitchOrFatal(loaderstate, ctx, err)
 		}
 	}
 }

src/cmd/go/internal/toolchain/switch.go

@@ -116,8 +116,8 @@ var counterSwitchExec = counter.New("go/toolchain/switch-exec")
 
 // SwitchOrFatal attempts a toolchain switch based on the information in err
 // and otherwise falls back to base.Fatal(err).
-func SwitchOrFatal(ctx context.Context, err error) {
+func SwitchOrFatal(loaderstate *modload.State, ctx context.Context, err error) {
-	s := NewSwitcher(modload.LoaderState)
+	s := NewSwitcher(loaderstate)
 	s.Error(err)
 	s.Switch(ctx)
 	base.Exit()

src/cmd/go/internal/workcmd/sync.go

@@ -56,7 +56,7 @@ func runSync(ctx context.Context, cmd *base.Command, args []string) {
 
 	_, err := modload.LoadModGraph(ctx, "")
 	if err != nil {
-		toolchain.SwitchOrFatal(ctx, err)
+		toolchain.SwitchOrFatal(modload.LoaderState, ctx, err)
 	}
 	mustSelectFor := map[module.Version][]module.Version{}