internal/platform,cmd/dist: export the list of supported platforms

Also switch internal/platform to commit the generated code instead of
regenerating it in cmd/dist. Nothing in the generated code depends on
the target configuration, and committing the source file makes it
more amenable to searching and indexing (particularly on
https://cs.opensource.google/go/go).

For #60939.

Change-Id: I9133dfd5129b3c4d7457267589dfac5e7ecbef65
Reviewed-on: https://go-review.googlesource.com/c/go/+/505175
TryBot-Result: Gopher Robot <gobot@golang.org>
Auto-Submit: Bryan Mills <bcmills@google.com>
Reviewed-by: Austin Clements <austin@google.com>
Run-TryBot: Bryan Mills <bcmills@google.com>

9 files changed, 275 insertions, 45 deletions

diff --git a/.gitignore b/.gitignore
index 52263cdb80..7978d68b76 100644
--- a/.gitignore
+++ b/.gitignore
@@ -33,12 +33,10 @@ _testmain.go
 /src/cmd/cgo/zdefaultcc.go
 /src/cmd/dist/dist
 /src/cmd/go/internal/cfg/zdefaultcc.go
-/src/cmd/go/internal/cfg/zosarch.go
 /src/cmd/internal/objabi/zbootstrap.go
 /src/go/build/zcgo.go
 /src/go/doc/headscan
 /src/internal/buildcfg/zbootstrap.go
-/src/internal/platform/zosarch.go
 /src/runtime/internal/sys/zversion.go
 /src/unicode/maketables
 /src/time/tzdata/zzipdata.go
diff --git a/src/cmd/dist/build.go b/src/cmd/dist/build.go
index 4b77ed36f7..8973a87168 100644
--- a/src/cmd/dist/build.go
+++ b/src/cmd/dist/build.go
@@ -631,7 +631,6 @@ var gentab = []struct {
 }{
 	{"go/build", "zcgo.go", mkzcgo},
 	{"cmd/go/internal/cfg", "zdefaultcc.go", mkzdefaultcc},
-	{"internal/platform", "zosarch.go", mkzosarch},
 	{"runtime/internal/sys", "zversion.go", mkzversion},
 	{"time/tzdata", "zzipdata.go", mktzdata},
 }
@@ -1899,11 +1898,12 @@ func cmdversion() {
 // cmdlist lists all supported platforms.
 func cmdlist() {
 	jsonFlag := flag.Bool("json", false, "produce JSON output")
+	brokenFlag := flag.Bool("broken", false, "include broken ports")
 	xflagparse(0)
 
 	var plats []string
 	for p := range cgoEnabled {
-		if broken[p] {
+		if broken[p] && !*brokenFlag {
 			continue
 		}
 		plats = append(plats, p)
@@ -1922,6 +1922,7 @@ func cmdlist() {
 		GOARCH       string
 		CgoSupported bool
 		FirstClass   bool
+		Broken       bool `json:",omitempty"`
 	}
 	var results []jsonResult
 	for _, p := range plats {
@@ -1930,7 +1931,9 @@ func cmdlist() {
 			GOOS:         fields[0],
 			GOARCH:       fields[1],
 			CgoSupported: cgoEnabled[p],
-			FirstClass:   firstClass[p]})
+			FirstClass:   firstClass[p],
+			Broken:       broken[p],
+		})
 	}
 	out, err := json.MarshalIndent(results, "", "\t")
 	if err != nil {
diff --git a/src/cmd/dist/buildruntime.go b/src/cmd/dist/buildruntime.go
index b3fe8b02d8..1de78f0fdb 100644
--- a/src/cmd/dist/buildruntime.go
+++ b/src/cmd/dist/buildruntime.go
@@ -6,7 +6,6 @@ package main
 
 import (
 	"fmt"
-	"sort"
 	"strings"
 )
 
@@ -80,25 +79,3 @@ func mkobjabi(file string) {
 
 	writefile(buf.String(), file, writeSkipSame)
 }
-
-// mkzosarch writes zosarch.go for internal/platform.
-func mkzosarch(dir, file string) {
-	// sort for deterministic file contents.
-	var list []string
-	for plat := range cgoEnabled {
-		list = append(list, plat)
-	}
-	sort.Strings(list)
-
-	var buf strings.Builder
-	writeHeader(&buf)
-	fmt.Fprintf(&buf, "package platform\n")
-	fmt.Fprintln(&buf)
-	fmt.Fprintf(&buf, "var osArchSupportsCgo = map[string]bool{\n")
-	for _, plat := range list {
-		fmt.Fprintf(&buf, "\t\t%s: %v,\n", quote(plat), cgoEnabled[plat])
-	}
-	fmt.Fprintf(&buf, "}\n")
-
-	writefile(buf.String(), file, writeSkipSame)
-}
diff --git a/src/cmd/dist/buildtool.go b/src/cmd/dist/buildtool.go
index 5e026f7bed..e638d51af7 100644
--- a/src/cmd/dist/buildtool.go
+++ b/src/cmd/dist/buildtool.go
@@ -126,7 +126,6 @@ func bootstrapBuildTools() {
 
 	mkbuildcfg(pathf("%s/src/internal/buildcfg/zbootstrap.go", goroot))
 	mkobjabi(pathf("%s/src/cmd/internal/objabi/zbootstrap.go", goroot))
-	mkzosarch("", pathf("%s/src/internal/platform/zosarch.go", goroot))
 
 	// Use $GOROOT/pkg/bootstrap as the bootstrap workspace root.
 	// We use a subdirectory of $GOROOT/pkg because that's the
diff --git a/src/cmd/dist/main.go b/src/cmd/dist/main.go
index 5f3e5bc9bd..f3425a9dd8 100644
--- a/src/cmd/dist/main.go
+++ b/src/cmd/dist/main.go
@@ -16,14 +16,14 @@ func usage() {
 	xprintf(`usage: go tool dist [command]
 Commands are:
 
-banner         print installation banner
-bootstrap      rebuild everything
-clean          deletes all built files
-env [-p]       print environment (-p: include $PATH)
-install [dir]  install individual directory
-list [-json]   list all supported platforms
-test [-h]      run Go test(s)
-version        print Go version
+banner                  print installation banner
+bootstrap               rebuild everything
+clean                   deletes all built files
+env [-p]                print environment (-p: include $PATH)
+install [dir]           install individual directory
+list [-json] [-broken]  list all supported platforms
+test [-h]               run Go test(s)
+version                 print Go version
 
 All commands take -v flags to emit extra information.
 `)
diff --git a/src/cmd/distpack/pack.go b/src/cmd/distpack/pack.go
index 6867ac17c2..e8b5255e63 100644
--- a/src/cmd/distpack/pack.go
+++ b/src/cmd/distpack/pack.go
@@ -127,7 +127,6 @@ func main() {
 		// Generated during cmd/dist. See ../dist/build.go:/gentab.
 		"src/cmd/go/internal/cfg/zdefaultcc.go",
 		"src/go/build/zcgo.go",
-		"src/internal/platform/zosarch.go",
 		"src/runtime/internal/sys/zversion.go",
 		"src/time/tzdata/zzipdata.go",
 
diff --git a/src/internal/platform/supported.go b/src/internal/platform/supported.go
index e762bb304e..230a952d2d 100644
--- a/src/internal/platform/supported.go
+++ b/src/internal/platform/supported.go
@@ -2,8 +2,19 @@
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
+//go:generate go test . -run=TestGenerated -fix
+
 package platform
 
+// An OSArch is a pair of GOOS and GOARCH values indicating a platform.
+type OSArch struct {
+	GOOS, GOARCH string
+}
+
+func (p OSArch) String() string {
+	return p.GOOS + "/" + p.GOARCH
+}
+
 // RaceDetectorSupported reports whether goos/goarch supports the race
 // detector. There is a copy of this function in cmd/dist/test.go.
 // Race detector only supports 48-bit VMA on arm64. But it will always
@@ -123,11 +134,11 @@ func BuildModeSupported(compiler, buildmode, goos, goarch string) bool {
 		return true
 	}
 
-	platform := goos + "/" + goarch
-	if _, ok := osArchSupportsCgo[platform]; !ok {
+	if _, ok := distInfo[OSArch{goos, goarch}]; !ok {
 		return false // platform unrecognized
 	}
 
+	platform := goos + "/" + goarch
 	switch buildmode {
 	case "archive":
 		return true
@@ -239,11 +250,6 @@ func DefaultPIE(goos, goarch string, isRace bool) bool {
 	return false
 }
 
-// CgoSupported reports whether goos/goarch supports cgo.
-func CgoSupported(goos, goarch string) bool {
-	return osArchSupportsCgo[goos+"/"+goarch]
-}
-
 // ExecutableHasDWARF reports whether the linked executable includes DWARF
 // symbols on goos/goarch.
 func ExecutableHasDWARF(goos, goarch string) bool {
@@ -253,3 +259,28 @@ func ExecutableHasDWARF(goos, goarch string) bool {
 	}
 	return true
 }
+
+// osArchInfo describes information about an OSArch extracted from cmd/dist and
+// stored in the generated distInfo map.
+type osArchInfo struct {
+	CgoSupported bool
+	FirstClass   bool
+	Broken       bool
+}
+
+// CgoSupported reports whether goos/goarch supports cgo.
+func CgoSupported(goos, goarch string) bool {
+	return distInfo[OSArch{goos, goarch}].CgoSupported
+}
+
+// FirstClass reports whether goos/goarch is considered a “first class” port.
+// (See https://go.dev/wiki/PortingPolicy#first-class-ports.)
+func FirstClass(goos, goarch string) bool {
+	return distInfo[OSArch{goos, goarch}].FirstClass
+}
+
+// Broken reportsr whether goos/goarch is considered a broken port.
+// (See https://go.dev/wiki/PortingPolicy#broken-ports.)
+func Broken(goos, goarch string) bool {
+	return distInfo[OSArch{goos, goarch}].Broken
+}
diff --git a/src/internal/platform/zosarch.go b/src/internal/platform/zosarch.go
new file mode 100644
index 0000000000..7f5a290332
--- /dev/null
+++ b/src/internal/platform/zosarch.go
@@ -0,0 +1,114 @@
+// Code generated by go test internal/platform -fix. DO NOT EDIT.
+
+// To change the information in this file, edit the cgoEnabled and/or firstClass
+// maps in cmd/dist/build.go, then run 'go generate internal/platform'.
+
+package platform
+
+// List is the list of all valid GOOS/GOARCH combinations,
+// including known-broken ports.
+var List = []OSArch{
+	{"aix", "ppc64"},
+	{"android", "386"},
+	{"android", "amd64"},
+	{"android", "arm"},
+	{"android", "arm64"},
+	{"darwin", "amd64"},
+	{"darwin", "arm64"},
+	{"dragonfly", "amd64"},
+	{"freebsd", "386"},
+	{"freebsd", "amd64"},
+	{"freebsd", "arm"},
+	{"freebsd", "arm64"},
+	{"freebsd", "riscv64"},
+	{"illumos", "amd64"},
+	{"ios", "amd64"},
+	{"ios", "arm64"},
+	{"js", "wasm"},
+	{"linux", "386"},
+	{"linux", "amd64"},
+	{"linux", "arm"},
+	{"linux", "arm64"},
+	{"linux", "loong64"},
+	{"linux", "mips"},
+	{"linux", "mips64"},
+	{"linux", "mips64le"},
+	{"linux", "mipsle"},
+	{"linux", "ppc64"},
+	{"linux", "ppc64le"},
+	{"linux", "riscv64"},
+	{"linux", "s390x"},
+	{"linux", "sparc64"},
+	{"netbsd", "386"},
+	{"netbsd", "amd64"},
+	{"netbsd", "arm"},
+	{"netbsd", "arm64"},
+	{"openbsd", "386"},
+	{"openbsd", "amd64"},
+	{"openbsd", "arm"},
+	{"openbsd", "arm64"},
+	{"openbsd", "mips64"},
+	{"openbsd", "ppc64"},
+	{"plan9", "386"},
+	{"plan9", "amd64"},
+	{"plan9", "arm"},
+	{"solaris", "amd64"},
+	{"wasip1", "wasm"},
+	{"windows", "386"},
+	{"windows", "amd64"},
+	{"windows", "arm"},
+	{"windows", "arm64"},
+}
+
+var distInfo = map[OSArch]osArchInfo{
+	{"aix", "ppc64"}:       {CgoSupported: true},
+	{"android", "386"}:     {CgoSupported: true},
+	{"android", "amd64"}:   {CgoSupported: true},
+	{"android", "arm"}:     {CgoSupported: true},
+	{"android", "arm64"}:   {CgoSupported: true},
+	{"darwin", "amd64"}:    {CgoSupported: true, FirstClass: true},
+	{"darwin", "arm64"}:    {CgoSupported: true, FirstClass: true},
+	{"dragonfly", "amd64"}: {CgoSupported: true},
+	{"freebsd", "386"}:     {CgoSupported: true},
+	{"freebsd", "amd64"}:   {CgoSupported: true},
+	{"freebsd", "arm"}:     {CgoSupported: true},
+	{"freebsd", "arm64"}:   {CgoSupported: true},
+	{"freebsd", "riscv64"}: {CgoSupported: true},
+	{"illumos", "amd64"}:   {CgoSupported: true},
+	{"ios", "amd64"}:       {CgoSupported: true},
+	{"ios", "arm64"}:       {CgoSupported: true},
+	{"js", "wasm"}:         {},
+	{"linux", "386"}:       {CgoSupported: true, FirstClass: true},
+	{"linux", "amd64"}:     {CgoSupported: true, FirstClass: true},
+	{"linux", "arm"}:       {CgoSupported: true, FirstClass: true},
+	{"linux", "arm64"}:     {CgoSupported: true, FirstClass: true},
+	{"linux", "loong64"}:   {CgoSupported: true},
+	{"linux", "mips"}:      {CgoSupported: true},
+	{"linux", "mips64"}:    {CgoSupported: true},
+	{"linux", "mips64le"}:  {CgoSupported: true},
+	{"linux", "mipsle"}:    {CgoSupported: true},
+	{"linux", "ppc64"}:     {},
+	{"linux", "ppc64le"}:   {CgoSupported: true},
+	{"linux", "riscv64"}:   {CgoSupported: true},
+	{"linux", "s390x"}:     {CgoSupported: true},
+	{"linux", "sparc64"}:   {CgoSupported: true, Broken: true},
+	{"netbsd", "386"}:      {CgoSupported: true},
+	{"netbsd", "amd64"}:    {CgoSupported: true},
+	{"netbsd", "arm"}:      {CgoSupported: true},
+	{"netbsd", "arm64"}:    {CgoSupported: true},
+	{"openbsd", "386"}:     {CgoSupported: true},
+	{"openbsd", "amd64"}:   {CgoSupported: true},
+	{"openbsd", "arm"}:     {CgoSupported: true},
+	{"openbsd", "arm64"}:   {CgoSupported: true},
+	{"openbsd", "mips64"}:  {CgoSupported: true, Broken: true},
+	{"openbsd", "ppc64"}:   {Broken: true},
+	{"plan9", "386"}:       {},
+	{"plan9", "amd64"}:     {},
+	{"plan9", "arm"}:       {},
+	{"solaris", "amd64"}:   {CgoSupported: true},
+	{"wasip1", "wasm"}:     {},
+	{"windows", "386"}:     {CgoSupported: true, FirstClass: true},
+	{"windows", "amd64"}:   {CgoSupported: true, FirstClass: true},
+	{"windows", "arm"}:     {},
+	{"windows", "arm64"}:   {CgoSupported: true},
+}
diff --git a/src/internal/platform/zosarch_test.go b/src/internal/platform/zosarch_test.go
new file mode 100644
index 0000000000..e8ffe9e75d
--- /dev/null
+++ b/src/internal/platform/zosarch_test.go
@@ -0,0 +1,109 @@
+// Copyright 2023 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package platform_test
+
+import (
+	"bytes"
+	"encoding/json"
+	"flag"
+	"internal/diff"
+	"internal/testenv"
+	"os"
+	"os/exec"
+	"testing"
+	"text/template"
+)
+
+var flagFix = flag.Bool("fix", false, "if true, fix out-of-date generated files")
+
+// TestGenerated verifies that zosarch.go is up to date,
+// or regenerates it if the -fix flag is set.
+func TestGenerated(t *testing.T) {
+	testenv.MustHaveGoRun(t)
+
+	// Here we use 'go run cmd/dist' instead of 'go tool dist' in case the
+	// installed cmd/dist is stale or missing. We don't want to miss a
+	// skew in the data due to a stale binary.
+	cmd := testenv.Command(t, "go", "run", "cmd/dist", "list", "-json", "-broken")
+
+	// cmd/dist requires GOROOT to be set explicitly in the environment.
+	cmd.Env = append(cmd.Environ(), "GOROOT="+testenv.GOROOT(t))
+
+	out, err := cmd.Output()
+	if err != nil {
+		if ee, ok := err.(*exec.ExitError); ok && len(ee.Stderr) > 0 {
+			t.Logf("stderr:\n%s", ee.Stderr)
+		}
+		t.Fatalf("%v: %v", cmd, err)
+	}
+
+	type listEntry struct {
+		GOOS, GOARCH string
+		CgoSupported bool
+		FirstClass   bool
+		Broken       bool
+	}
+	var entries []listEntry
+	if err := json.Unmarshal(out, &entries); err != nil {
+		t.Fatal(err)
+	}
+
+	tmplOut := new(bytes.Buffer)
+	tmpl := template.Must(template.New("zosarch").Parse(zosarchTmpl))
+	err = tmpl.Execute(tmplOut, entries)
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	cmd = testenv.Command(t, "gofmt")
+	cmd.Stdin = bytes.NewReader(tmplOut.Bytes())
+	want, err := cmd.Output()
+	if err != nil {
+		t.Logf("stdin:\n%s", tmplOut.Bytes())
+		if ee, ok := err.(*exec.ExitError); ok && len(ee.Stderr) > 0 {
+			t.Logf("stderr:\n%s", ee.Stderr)
+		}
+		t.Fatalf("%v: %v", cmd, err)
+	}
+
+	got, err := os.ReadFile("zosarch.go")
+	if err == nil && bytes.Equal(got, want) {
+		return
+	}
+
+	if !*flagFix {
+		if err != nil {
+			t.Log(err)
+		} else {
+			t.Logf("diff:\n%s", diff.Diff("zosarch.go", got, "want", want))
+		}
+		t.Fatalf("zosarch.go is missing or out of date; to regenerate, run\ngo generate internal/platform")
+	}
+
+	if err := os.WriteFile("zosarch.go", want, 0666); err != nil {
+		t.Fatal(err)
+	}
+}
+
+const zosarchTmpl = `// Code generated by go test internal/platform -fix. DO NOT EDIT.
+
+// To change the information in this file, edit the cgoEnabled and/or firstClass
+// maps in cmd/dist/build.go, then run 'go generate internal/platform'.
+
+package platform
+
+// List is the list of all valid GOOS/GOARCH combinations,
+// including known-broken ports.
+var List = []OSArch{
+{{range .}}	{ {{ printf "%q" .GOOS }}, {{ printf "%q" .GOARCH }} },
+{{end}}
+}
+
+var distInfo = map[OSArch]osArchInfo {
+{{range .}}	{ {{ printf "%q" .GOOS }}, {{ printf "%q" .GOARCH }} }:
+{ {{if .CgoSupported}}CgoSupported: true, {{end}}{{if .FirstClass}}FirstClass: true, {{end}}{{if .Broken}} Broken: true, {{end}} },
+{{end}}
+}
+`