cmd/dist: move cmd/go z files to cmd/go/internal/cfg

This is one CL in a long sequence of changes to break up the
go command from one package into a plausible group of packages.

This sequence is concerned only with moving code, not changing
or cleaning up code. There will still be more cleanup after this sequence.

The entire sequence will be submitted together: it is not a goal
for the tree to build at every step.

For #18653.

Change-Id: I6ee5b053683034ea9462a9a0a4ea4f5ad24fa5a1
Reviewed-on: https://go-review.googlesource.com/36192Reviewed-by: David Crawshaw <crawshaw@golang.org>

.gitignore

@@ -31,8 +31,8 @@ _testmain.go
 /pkg/
 /src/*.*/
 /src/cmd/cgo/zdefaultcc.go
-/src/cmd/go/zdefaultcc.go
-/src/cmd/go/zosarch.go
+/src/cmd/go/internal/cfg/zdefaultcc.go
+/src/cmd/go/internal/cfg/zosarch.go
 /src/cmd/internal/obj/zbootstrap.go
 /src/go/build/zcgo.go
 /src/go/doc/headscan

src/cmd/dist/build.go

@@ -471,7 +471,7 @@ var deptab = []struct {
 	prefix string   // prefix of target
 	dep    []string // dependency tweaks for targets with that prefix
 }{
-	{"cmd/go", []string{
+	{"cmd/go/internal/cfg", []string{
 		"zdefaultcc.go",
 		"zosarch.go",
 	}},
@@ -543,7 +543,7 @@ func install(dir string) {
 	path := pathf("%s/src/%s", goroot, dir)
 	name := filepath.Base(dir)
 
-	ispkg := !strings.HasPrefix(dir, "cmd/") || strings.HasPrefix(dir, "cmd/internal/") || strings.HasPrefix(dir, "cmd/asm/internal/")
+	ispkg := !strings.HasPrefix(dir, "cmd/") || strings.Contains(dir, "/internal/")
 
 	// Start final link command line.
 	// Note: code below knows that link.p[targ] is the target.

src/cmd/dist/buildgo.go

@@ -25,7 +25,20 @@ import (
 // It is invoked to write cmd/go/zdefaultcc.go
 // but we also write cmd/cgo/zdefaultcc.go
 func mkzdefaultcc(dir, file string) {
-	out := fmt.Sprintf(
+	outGo := fmt.Sprintf(
+		"// auto generated by go tool dist\n"+
+			"\n"+
+			"package cfg\n"+
+			"\n"+
+			"const DefaultCC = `%s`\n"+
+			"const DefaultCXX = `%s`\n"+
+			"const DefaultPkgConfig = `%s`\n",
+		defaultcctarget, defaultcxxtarget, defaultpkgconfigtarget)
+
+	writefile(outGo, file, writeSkipSame)
+
+	// Convert file name to replace: turn go/internal/cfg into cgo.
+	outCgo := fmt.Sprintf(
 		"// auto generated by go tool dist\n"+
 			"\n"+
 			"package main\n"+
@@ -35,12 +48,9 @@ func mkzdefaultcc(dir, file string) {
 			"const defaultPkgConfig = `%s`\n",
 		defaultcctarget, defaultcxxtarget, defaultpkgconfigtarget)
 
-	writefile(out, file, writeSkipSame)
-
-	// Convert file name to replace: turn go into cgo.
-	i := len(file) - len("go/zdefaultcc.go")
-	file = file[:i] + "c" + file[i:]
-	writefile(out, file, writeSkipSame)
+	i := len(file) - len("go/internal/cfg/zdefaultcc.go")
+	file = file[:i] + "cgo/zdefaultcc.go"
+	writefile(outCgo, file, writeSkipSame)
 }
 
 // mkzcgo writes zosarch.go for cmd/go.
@@ -54,8 +64,8 @@ func mkzosarch(dir, file string) {
 
 	var buf bytes.Buffer
 	buf.WriteString("// auto generated by go tool dist\n\n")
-	buf.WriteString("package main\n\n")
-	fmt.Fprintf(&buf, "var osArchSupportsCgo = map[string]bool{\n")
+	buf.WriteString("package cfg\n\n")
+	fmt.Fprintf(&buf, "var OSArchSupportsCgo = map[string]bool{\n")
 	for _, plat := range list {
 		fmt.Fprintf(&buf, "\t%q: %v,\n", plat, cgoEnabled[plat])
 	}