[release-branch.go1.18] cmd/go: ignore the workspace when running a package at a specified version

Fixes #51390

Change-Id: I805e66809b2aafb48f7040dee72910dd7d6c1396
Reviewed-on: https://go-review.googlesource.com/c/go/+/388917
Trust: Bryan Mills <bcmills@google.com>
Run-TryBot: Bryan Mills <bcmills@google.com>
TryBot-Result: Gopher Robot <gobot@golang.org>
Reviewed-by: Michael Matloob <matloob@golang.org>
(cherry picked from commit 86b5f6a7be)
Reviewed-on: https://go-review.googlesource.com/c/go/+/389575
Trust: Dmitri Shuralyov <dmitshur@golang.org>
Run-TryBot: Dmitri Shuralyov <dmitshur@golang.org>

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

@@ -288,6 +288,11 @@ func BinDir() string {
 // operate in workspace mode. It should not be called by other commands,
 // for example 'go mod tidy', that don't operate in workspace mode.
 func InitWorkfile() {
+	if RootMode == NoRoot {
+		workFilePath = ""
+		return
+	}
+
 	switch gowork := cfg.Getenv("GOWORK"); gowork {
 	case "off":
 		workFilePath = ""

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

@@ -73,8 +73,6 @@ func printStderr(args ...any) (int, error) {
 }
 
 func runRun(ctx context.Context, cmd *base.Command, args []string) {
-	modload.InitWorkfile()
-
 	if shouldUseOutsideModuleMode(args) {
 		// Set global module flags for 'go run cmd@version'.
 		// This must be done before modload.Init, but we need to call work.BuildInit
@@ -84,7 +82,10 @@ func runRun(ctx context.Context, cmd *base.Command, args []string) {
 		modload.RootMode = modload.NoRoot
 		modload.AllowMissingModuleImports()
 		modload.Init()
+	} else {
+		modload.InitWorkfile()
 	}
+
 	work.BuildInit()
 	var b work.Builder
 	b.Init()

src/cmd/go/testdata/script/run_work_versioned.txt

@@ -0,0 +1,16 @@
+[short] skip
+go run example.com/printversion@v0.1.0
+stdout '^main is example.com/printversion v0.1.0$'
+
+-- go.work --
+go 1.18
+
+use (
+	.
+)
+-- go.mod --
+module example
+
+go 1.18
+
+require example.com/printversion v1.0.0