internal/buildcfg: move build configuration out of cmd/internal/objabi

The go/build package needs access to this configuration,
so move it into a new package available to the standard library.

Change-Id: I868a94148b52350c76116451f4ad9191246adcff
Reviewed-on: https://go-review.googlesource.com/c/go/+/310731
Trust: Russ Cox <rsc@golang.org>
Run-TryBot: Russ Cox <rsc@golang.org>
Reviewed-by: Austin Clements <austin@google.com>
Reviewed-by: Jay Conrod <jayconrod@google.com>

2 files changed, 26 insertions, 15 deletions

diff --git a/src/cmd/dist/buildruntime.go b/src/cmd/dist/buildruntime.go
index 3ef551e187..54e935ad3b 100644
--- a/src/cmd/dist/buildruntime.go
+++ b/src/cmd/dist/buildruntime.go
@@ -32,22 +32,15 @@ func mkzversion(dir, file string) {
 	writefile(buf.String(), file, writeSkipSame)
 }
 
-// mkzbootstrap writes cmd/internal/objabi/zbootstrap.go:
+// mkbuildcfg writes internal/buildcfg/zbootstrap.go:
 //
-//	package objabi
+//	package buildcfg
 //
 //	const defaultGOROOT = <goroot>
 //	const defaultGO386 = <go386>
-//	const defaultGOARM = <goarm>
-//	const defaultGOMIPS = <gomips>
-//	const defaultGOMIPS64 = <gomips64>
-//	const defaultGOPPC64 = <goppc64>
+//	...
 //	const defaultGOOS = runtime.GOOS
 //	const defaultGOARCH = runtime.GOARCH
-//	const defaultGOEXPERIMENT = <goexperiment>
-//	const defaultGO_EXTLINK_ENABLED = <goextlinkenabled>
-//	const version = <version>
-//	const stackGuardMultiplierDefault = <multiplier value>
 //
 // The use of runtime.GOOS and runtime.GOARCH makes sure that
 // a cross-compiled compiler expects to compile for its own target
@@ -58,11 +51,11 @@ func mkzversion(dir, file string) {
 // the resulting compiler will default to generating linux/ppc64 object files.
 // This is more useful than having it default to generating objects for the
 // original target (in this example, a Mac).
-func mkzbootstrap(file string) {
+func mkbuildcfg(file string) {
 	var buf bytes.Buffer
 	fmt.Fprintf(&buf, "// Code generated by go tool dist; DO NOT EDIT.\n")
 	fmt.Fprintln(&buf)
-	fmt.Fprintf(&buf, "package objabi\n")
+	fmt.Fprintf(&buf, "package buildcfg\n")
 	fmt.Fprintln(&buf)
 	fmt.Fprintf(&buf, "import \"runtime\"\n")
 	fmt.Fprintln(&buf)
@@ -71,12 +64,28 @@ func mkzbootstrap(file string) {
 	fmt.Fprintf(&buf, "const defaultGOMIPS = `%s`\n", gomips)
 	fmt.Fprintf(&buf, "const defaultGOMIPS64 = `%s`\n", gomips64)
 	fmt.Fprintf(&buf, "const defaultGOPPC64 = `%s`\n", goppc64)
-	fmt.Fprintf(&buf, "const defaultGOOS = runtime.GOOS\n")
-	fmt.Fprintf(&buf, "const defaultGOARCH = runtime.GOARCH\n")
 	fmt.Fprintf(&buf, "const defaultGOEXPERIMENT = `%s`\n", goexperiment)
 	fmt.Fprintf(&buf, "const defaultGO_EXTLINK_ENABLED = `%s`\n", goextlinkenabled)
 	fmt.Fprintf(&buf, "const defaultGO_LDSO = `%s`\n", defaultldso)
 	fmt.Fprintf(&buf, "const version = `%s`\n", findgoversion())
+	fmt.Fprintf(&buf, "const defaultGOOS = runtime.GOOS\n")
+	fmt.Fprintf(&buf, "const defaultGOARCH = runtime.GOARCH\n")
+
+	writefile(buf.String(), file, writeSkipSame)
+}
+
+// mkobjabi writes cmd/internal/objabi/zbootstrap.go:
+//
+//	package objabi
+//
+//	const stackGuardMultiplierDefault = <multiplier value>
+//
+func mkobjabi(file string) {
+	var buf bytes.Buffer
+	fmt.Fprintf(&buf, "// Code generated by go tool dist; DO NOT EDIT.\n")
+	fmt.Fprintln(&buf)
+	fmt.Fprintf(&buf, "package objabi\n")
+	fmt.Fprintln(&buf)
 	fmt.Fprintf(&buf, "const stackGuardMultiplierDefault = %d\n", stackGuardMultiplierDefault())
 
 	writefile(buf.String(), file, writeSkipSame)
diff --git a/src/cmd/dist/buildtool.go b/src/cmd/dist/buildtool.go
index 44b1886968..26b33e389f 100644
--- a/src/cmd/dist/buildtool.go
+++ b/src/cmd/dist/buildtool.go
@@ -58,6 +58,7 @@ var bootstrapDirs = []string{
 	"debug/macho",
 	"debug/pe",
 	"go/constant",
+	"internal/buildcfg",
 	"internal/goexperiment",
 	"internal/goversion",
 	"internal/race",
@@ -98,7 +99,8 @@ func bootstrapBuildTools() {
 	}
 	xprintf("Building Go toolchain1 using %s.\n", goroot_bootstrap)
 
-	mkzbootstrap(pathf("%s/src/cmd/internal/objabi/zbootstrap.go", goroot))
+	mkbuildcfg(pathf("%s/src/internal/buildcfg/zbootstrap.go", goroot))
+	mkobjabi(pathf("%s/src/cmd/internal/objabi/zbootstrap.go", goroot))
 
 	// Use $GOROOT/pkg/bootstrap as the bootstrap workspace root.
 	// We use a subdirectory of $GOROOT/pkg because that's the