cmd/go: refactor usage of ForceUseModules

This commit refactors usage of the global variable `ForceUseModules`
to the global LoaderState field of the same name.

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

[git-generate]
cd src/cmd/go/internal/modload
rf 'mv State.forceUseModules State.ForceUseModules'
rf 'ex { ForceUseModules -> LoaderState.ForceUseModules }'
for dir in load modcmd modget run toolchain work workcmd ; do
  cd ../${dir}
  rf 'ex {
    import "cmd/go/internal/modload";
    modload.ForceUseModules -> modload.LoaderState.ForceUseModules
  }'
done
cd ../modload
rf 'add State.initialized \
// ForceUseModules may be set to force modules to be enabled when\
// GO111MODULE=auto or to report an error when GO111MODULE=off.'
rf 'rm ForceUseModules'

Change-Id: Ibdecfd273ff672516c9eb86279e5dfc6cdecb2ea
Reviewed-on: https://go-review.googlesource.com/c/go/+/698057
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/load/pkg.go

@@ -3348,7 +3348,7 @@ func GoFilesPackage(ctx context.Context, opts PackageOpts, gofiles []string) *Pa
 // would cause it to be interpreted differently if it were the main module
 // (replace, exclude).
 func PackagesAndErrorsOutsideModule(ctx context.Context, opts PackageOpts, args []string) ([]*Package, error) {
-	if !modload.ForceUseModules {
+	if !modload.LoaderState.ForceUseModules {
 		panic("modload.ForceUseModules must be true")
 	}
 	if modload.RootMode != modload.NoRoot {

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

@@ -112,7 +112,7 @@ func runDownload(ctx context.Context, cmd *base.Command, args []string) {
 	modload.InitWorkfile()
 
 	// Check whether modules are enabled and whether we're in a module.
-	modload.ForceUseModules = true
+	modload.LoaderState.ForceUseModules = true
 	modload.ExplicitWriteGoMod = true
 	haveExplicitArgs := len(args) > 0
 

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

@@ -57,7 +57,7 @@ func runGraph(ctx context.Context, cmd *base.Command, args []string) {
 	if len(args) > 0 {
 		base.Fatalf("go: 'go mod graph' accepts no arguments")
 	}
-	modload.ForceUseModules = true
+	modload.LoaderState.ForceUseModules = true
 	modload.RootMode = modload.NeedRoot
 
 	goVersion := graphGo.String()

src/cmd/go/internal/modcmd/init.go

@@ -43,6 +43,6 @@ func runInit(ctx context.Context, cmd *base.Command, args []string) {
 		modPath = args[0]
 	}
 
-	modload.ForceUseModules = true
+	modload.LoaderState.ForceUseModules = true
 	modload.CreateModFile(ctx, modPath) // does all the hard work
 }

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

@@ -119,7 +119,7 @@ func runTidy(ctx context.Context, cmd *base.Command, args []string) {
 	// those packages. In order to make 'go test' reproducible for the packages
 	// that are in 'all' but outside of the main module, we must explicitly
 	// request that their test dependencies be included.
-	modload.ForceUseModules = true
+	modload.LoaderState.ForceUseModules = true
 	modload.RootMode = modload.NeedRoot
 
 	goVersion := tidyGo.String()

src/cmd/go/internal/modcmd/vendor.go

@@ -77,7 +77,7 @@ func RunVendor(ctx context.Context, vendorE bool, vendorO string, args []string)
 	if len(args) != 0 {
 		base.Fatalf("go: 'go mod vendor' accepts no arguments")
 	}
-	modload.ForceUseModules = true
+	modload.LoaderState.ForceUseModules = true
 	modload.RootMode = modload.NeedRoot
 
 	loadOpts := modload.PackageOpts{

src/cmd/go/internal/modcmd/verify.go

@@ -50,7 +50,7 @@ func runVerify(ctx context.Context, cmd *base.Command, args []string) {
 		// NOTE(rsc): Could take a module pattern.
 		base.Fatalf("go: verify takes no arguments")
 	}
-	modload.ForceUseModules = true
+	modload.LoaderState.ForceUseModules = true
 	modload.RootMode = modload.NeedRoot
 
 	// Only verify up to GOMAXPROCS zips at once.

src/cmd/go/internal/modcmd/why.go

@@ -64,7 +64,7 @@ func init() {
 
 func runWhy(ctx context.Context, cmd *base.Command, args []string) {
 	modload.InitWorkfile()
-	modload.ForceUseModules = true
+	modload.LoaderState.ForceUseModules = true
 	modload.RootMode = modload.NeedRoot
 	modload.ExplicitWriteGoMod = true // don't write go.mod in ListModules
 

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

@@ -298,7 +298,7 @@ func runGet(ctx context.Context, cmd *base.Command, args []string) {
 		base.Fatalf("go: -insecure flag is no longer supported; use GOINSECURE instead")
 	}
 
-	modload.ForceUseModules = true
+	modload.LoaderState.ForceUseModules = true
 
 	// Do not allow any updating of go.mod until we've applied
 	// all the requested changes and checked that the result matches

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

@@ -41,10 +41,6 @@ var (
 	// RootMode determines whether a module root is needed.
 	RootMode Root
 
-	// ForceUseModules may be set to force modules to be enabled when
-	// GO111MODULE=auto or to report an error when GO111MODULE=off.
-	ForceUseModules bool
-
 	allowMissingModuleImports bool
 
 	// ExplicitWriteGoMod prevents LoadPackages, ListModules, and other functions
@@ -96,7 +92,7 @@ func EnterWorkspace(ctx context.Context) (exit func(), err error) {
 
 	// Reset the state to a clean state.
 	oldstate := setState(State{})
-	ForceUseModules = true
+	LoaderState.ForceUseModules = true
 
 	// Load in workspace mode.
 	InitWorkfile()
@@ -406,7 +402,7 @@ func Reset() {
 func setState(s State) State {
 	oldState := State{
 		initialized:     LoaderState.initialized,
-		forceUseModules: ForceUseModules,
+		ForceUseModules: LoaderState.ForceUseModules,
 		rootMode:        RootMode,
 		modRoots:        modRoots,
 		modulesEnabled:  cfg.ModulesEnabled,
@@ -414,7 +410,7 @@ func setState(s State) State {
 		requirements:    requirements,
 	}
 	LoaderState.initialized = s.initialized
-	ForceUseModules = s.forceUseModules
+	LoaderState.ForceUseModules = s.ForceUseModules
 	RootMode = s.rootMode
 	modRoots = s.modRoots
 	cfg.ModulesEnabled = s.modulesEnabled
@@ -430,7 +426,10 @@ func setState(s State) State {
 
 type State struct {
 	initialized bool
-	forceUseModules bool
+
+	// ForceUseModules may be set to force modules to be enabled when
+	// GO111MODULE=auto or to report an error when GO111MODULE=off.
+	ForceUseModules bool
 	rootMode        Root
 	modRoots        []string
 	modulesEnabled  bool
@@ -465,11 +464,11 @@ func Init() {
 	default:
 		base.Fatalf("go: unknown environment setting GO111MODULE=%s", env)
 	case "auto":
-		mustUseModules = ForceUseModules
+		mustUseModules = LoaderState.ForceUseModules
 	case "on", "":
 		mustUseModules = true
 	case "off":
-		if ForceUseModules {
+		if LoaderState.ForceUseModules {
 			base.Fatalf("go: modules disabled by GO111MODULE=off; see 'go help modules'")
 		}
 		mustUseModules = false

src/cmd/go/internal/run/run.go

@@ -76,7 +76,7 @@ func runRun(ctx context.Context, cmd *base.Command, args []string) {
 		// This must be done before modload.Init, but we need to call work.BuildInit
 		// before loading packages, since it affects package locations, e.g.,
 		// for -race and -msan.
-		modload.ForceUseModules = true
+		modload.LoaderState.ForceUseModules = true
 		modload.RootMode = modload.NoRoot
 		modload.AllowMissingModuleImports()
 		modload.Init()

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

@@ -353,7 +353,7 @@ func Exec(gotoolchain string) {
 
 	// Set up modules without an explicit go.mod, to download distribution.
 	modload.Reset()
-	modload.ForceUseModules = true
+	modload.LoaderState.ForceUseModules = true
 	modload.RootMode = modload.NoRoot
 	modload.Init()
 
@@ -692,7 +692,7 @@ 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.ForceUseModules = true
+	modload.LoaderState.ForceUseModules = true
 	modload.RootMode = modload.NoRoot
 	modload.Init()
 	defer modload.Reset()

src/cmd/go/internal/work/build.go

@@ -859,7 +859,7 @@ func InstallPackages(ctx context.Context, patterns []string, pkgs []*load.Packag
 //
 // See golang.org/issue/40276 for details and rationale.
 func installOutsideModule(ctx context.Context, args []string) {
-	modload.ForceUseModules = true
+	modload.LoaderState.ForceUseModules = true
 	modload.RootMode = modload.NoRoot
 	modload.AllowMissingModuleImports()
 	modload.Init()

src/cmd/go/internal/workcmd/init.go

@@ -46,7 +46,7 @@ func init() {
 func runInit(ctx context.Context, cmd *base.Command, args []string) {
 	modload.InitWorkfile()
 
-	modload.ForceUseModules = true
+	modload.LoaderState.ForceUseModules = true
 
 	gowork := modload.WorkFilePath()
 	if gowork == "" {

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

@@ -48,7 +48,7 @@ func init() {
 }
 
 func runSync(ctx context.Context, cmd *base.Command, args []string) {
-	modload.ForceUseModules = true
+	modload.LoaderState.ForceUseModules = true
 	modload.InitWorkfile()
 	if modload.WorkFilePath() == "" {
 		base.Fatalf("go: no go.work file found\n\t(run 'go work init' first or specify path using GOWORK environment variable)")

src/cmd/go/internal/workcmd/use.go

@@ -61,7 +61,7 @@ func init() {
 }
 
 func runUse(ctx context.Context, cmd *base.Command, args []string) {
-	modload.ForceUseModules = true
+	modload.LoaderState.ForceUseModules = true
 	modload.InitWorkfile()
 	gowork := modload.WorkFilePath()
 	if gowork == "" {