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 golang#60939.

Change-Id: I9133dfd5129b3c4d7457267589dfac5e7ecbef65
Reviewed-on: https://go-review.googlesource.com/c/go/+/505175
TryBot-Result: Gopher Robot <[email protected]>
Auto-Submit: Bryan Mills <[email protected]>
Reviewed-by: Austin Clements <[email protected]>
Run-TryBot: Bryan Mills <[email protected]>

Author: Bryan C. Mills

.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

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 {

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)
-}

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

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.
 `)

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",
 

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
+}