cmd/dist: don't install tools that won't be shipped in distribution

We shouldn't be installing these tools because we will remove them in
distpack. Installing the tools will also prevent us from testing what
happens when the tools are missing.

The changes below this on the stack, CL 677775 (cmd/doc: build cmd/doc
directly into the go command) and CL 677636 (cmd/go/internal/cfg: fix
GOROOT setting when forcing host config) are needed for this change to
pass tests. The doc change is being done so we preserve the properties
in the tests that doc can be invoked without doing a build. It's not
strictly necessary (we could just remove the tests) but it's nice to
have. The GOROOT setting is a significant bug in switching the
configuration to host mode: the value of GOROOT wasn't being reset,
which caused issues for go commands built with trimpath, because
runtime.GOROOT wouldn't have the correct goroot value.

For #71867

Change-Id: I4181711ba117066b7d62d7d013ad4b186871cfb7
Reviewed-on: https://go-review.googlesource.com/c/go/+/677558
Reviewed-by: Dmitri Shuralyov <dmitshur@golang.org>
LUCI-TryBot-Result: Go LUCI <golang-scoped@luci-project-accounts.iam.gserviceaccount.com>
Reviewed-by: Dmitri Shuralyov <dmitshur@google.com>
Reviewed-by: Michael Matloob <matloob@google.com>

src/cmd/dist/build.go

@@ -1516,7 +1516,7 @@ func cmdbootstrap() {
 	}
 
 	// To recap, so far we have built the new toolchain
-	// (cmd/asm, cmd/cgo, cmd/compile, cmd/link)
+	// (cmd/asm, cmd/cgo, cmd/compile, cmd/link, cmd/preprofile)
 	// using the Go bootstrap toolchain and go command.
 	// Then we built the new go command (as go_bootstrap)
 	// using the new toolchain and our own build logic (above).
@@ -1589,6 +1589,18 @@ func cmdbootstrap() {
 		os.Setenv("GOCACHE", oldgocache)
 	}
 
+	// Keep in sync with binExes in cmd/distpack/pack.go.
+	binExesIncludedInDistpack := []string{"cmd/go", "cmd/gofmt"}
+
+	// Keep in sync with the filter in cmd/distpack/pack.go.
+	toolsIncludedInDistpack := []string{"cmd/asm", "cmd/cgo", "cmd/compile", "cmd/cover", "cmd/link", "cmd/preprofile", "cmd/vet"}
+
+	// We could install all tools in "cmd", but is unnecessary because we will
+	// remove them in distpack, so instead install the tools that will actually
+	// be included in distpack, which is a superset of toolchain. Not installing
+	// the tools will help us test what happens when the tools aren't present.
+	toolsToInstall := slices.Concat(binExesIncludedInDistpack, toolsIncludedInDistpack)
+
 	if goos == oldgoos && goarch == oldgoarch {
 		// Common case - not setting up for cross-compilation.
 		timelog("build", "toolchain")
@@ -1605,9 +1617,9 @@ func cmdbootstrap() {
 			xprintf("\n")
 		}
 		xprintf("Building commands for host, %s/%s.\n", goos, goarch)
-		goInstall(toolenv(), goBootstrap, "cmd")
+		goInstall(toolenv(), goBootstrap, toolsToInstall...)
-		checkNotStale(toolenv(), goBootstrap, "cmd")
+		checkNotStale(toolenv(), goBootstrap, toolsToInstall...)
-		checkNotStale(toolenv(), gorootBinGo, "cmd")
+		checkNotStale(toolenv(), gorootBinGo, toolsToInstall...)
 
 		timelog("build", "target toolchain")
 		if vflag > 0 {
@@ -1621,12 +1633,12 @@ func cmdbootstrap() {
 		xprintf("Building packages and commands for target, %s/%s.\n", goos, goarch)
 	}
 	goInstall(nil, goBootstrap, "std")
-	goInstall(toolenv(), goBootstrap, "cmd")
+	goInstall(toolenv(), goBootstrap, toolsToInstall...)
 	checkNotStale(toolenv(), goBootstrap, toolchain...)
 	checkNotStale(nil, goBootstrap, "std")
-	checkNotStale(toolenv(), goBootstrap, "cmd")
+	checkNotStale(toolenv(), goBootstrap, toolsToInstall...)
 	checkNotStale(nil, gorootBinGo, "std")
-	checkNotStale(toolenv(), gorootBinGo, "cmd")
+	checkNotStale(toolenv(), gorootBinGo, toolsToInstall...)
 	if debug {
 		run("", ShowOutput|CheckExit, pathf("%s/compile", tooldir), "-V=full")
 		checkNotStale(toolenv(), goBootstrap, toolchain...)
@@ -1677,7 +1689,7 @@ func cmdbootstrap() {
 
 	if distpack {
 		xprintf("Packaging archives for %s/%s.\n", goos, goarch)
-		run("", ShowOutput|CheckExit, pathf("%s/distpack", tooldir))
+		run("", ShowOutput|CheckExit, gorootBinGo, "tool", "distpack")
 	}
 
 	// Print trailing banner unless instructed otherwise.

src/cmd/distpack/pack.go

@@ -171,6 +171,7 @@ func main() {
 			switch strings.TrimSuffix(path.Base(name), ".exe") {
 			default:
 				return false
+			// Keep in sync with toolsIncludedInDistpack in cmd/dist/build.go.
 			case "asm", "cgo", "compile", "cover", "link", "preprofile", "vet":
 			}
 		}
@@ -179,6 +180,7 @@ func main() {
 
 	// Add go and gofmt to bin, using cross-compiled binaries
 	// if this is a cross-compiled distribution.
+	// Keep in sync with binExesIncludedInDistpack in cmd/dist/build.go.
 	binExes := []string{
 		"go",
 		"gofmt",