cmd/go: many improvements

* correct dependency calculations
* comment meaning of action fields
* new alias "std" like "all" but standard packages only
* add -o flag to 'go build'
* set up for parallel build (still serial)
* understand that import "C" depends on cgo, runtime/cgo

R=golang-dev, mikioh.mikioh
CC=golang-dev
https://golang.org/cl/5502055

src/cmd/go/help.go

@@ -27,6 +27,9 @@ The special import path "all" expands to all package directories
 found in all the GOPATH trees.  For example, 'go list all' 
 lists all the packages on the local system.
 
+The special import path "std" is like all but expands to just the
+packages in the standard Go library.
+
 An import path can also name a package to be downloaded from
 a remote repository.  Run 'go help remote' for details.
 

src/cmd/go/list.go

@@ -33,11 +33,12 @@ being passed to the template is:
         ImportPath string // import path of package in dir
         Dir        string // directory containing package sources
         Version    string // version of installed package (TODO)
+        Stale      bool   // would 'go install' do anything for this package?
 
         // Source files
         GoFiles  []string // .go source files (excluding CgoFiles)
         CFiles   []string // .c source files
-        HFiles []string // .h source files
+        HFiles   []string // .h source files
         SFiles   []string // .s source files
         CgoFiles []string // .go sources files that import "C"
 

src/cmd/go/main.go

@@ -185,8 +185,10 @@ func help(args []string) {
 
 // importPaths returns the import paths to use for the given command line.
 func importPaths(args []string) []string {
-	if len(args) == 1 && args[0] == "all" {
-		return allPackages()
+	if len(args) == 1 {
+		if args[0] == "all" || args[0] == "std" {
+			return allPackages(args[0])
+		}
 	}
 	if len(args) == 0 {
 		return []string{"."}
@@ -236,10 +238,13 @@ func run(cmdline ...string) {
 
 // allPackages returns all the packages that can be found
 // under the $GOPATH directories and $GOROOT.
-func allPackages() []string {
+func allPackages(what string) []string {
 	have := map[string]bool{
 		"builtin": true, // ignore pseudo-package that exists only for documentation
 	}
+	if !build.DefaultContext.CgoEnabled {
+		have["runtime/cgo"] = true // ignore during walk
+	}
 	var pkgs []string
 
 	// Commands
@@ -270,6 +275,9 @@ func allPackages() []string {
 	})
 
 	for _, t := range build.Path {
+		if what == "std" && !t.Goroot {
+			continue
+		}
 		src := t.SrcDir() + string(filepath.Separator)
 		filepath.Walk(src, func(path string, fi os.FileInfo, err error) error {
 			if err != nil || !fi.IsDir() {
@@ -281,15 +289,21 @@ func allPackages() []string {
 				return filepath.SkipDir
 			}
 
+			name := filepath.ToSlash(path[len(src):])
+			if what == "std" && strings.Contains(name, ".") {
+				return filepath.SkipDir
+			}
+			if have[name] {
+				return nil
+			}
+
 			_, err = build.ScanDir(path)
 			if err != nil {
 				return nil
 			}
-			name := filepath.ToSlash(path[len(src):])
-			if !have[name] {
-				pkgs = append(pkgs, name)
-				have[name] = true
-			}
+
+			pkgs = append(pkgs, name)
+			have[name] = true
 
 			// Avoid go/build test data.
 			// TODO: Move it into a testdata directory.

src/cmd/go/run.go

@@ -33,7 +33,7 @@ func runRun(cmd *Command, args []string) {
 	var b builder
 	b.init(*runA, *runN, *runX)
 	p := goFilesPackage(args, "")
-	p.targ = "" // force rebuild - no up-to-date copy anywhere
+	p.target = "" // must build - not up to date
 	a1 := b.action(modeBuild, modeBuild, p)
 	a := &action{f: (*builder).runProgram, deps: []*action{a1}}
 	b.do(a)
@@ -42,6 +42,6 @@ func runRun(cmd *Command, args []string) {
 // runProgram is the action for running a binary that has already
 // been compiled.  We ignore exit status.
 func (b *builder) runProgram(a *action) error {
-	run(a.deps[0].pkgbin)
+	run(a.deps[0].target)
 	return nil
 }

src/make.bash

@@ -89,7 +89,7 @@ echo; echo; echo %%%% making runtime generated files %%%%; echo
 (
 	cd "$GOROOT"/src/pkg/runtime
 	./autogen.sh
-	gomake install  # copy runtime.h to pkg directory
+	gomake install; gomake clean # copy runtime.h to pkg directory
 ) || exit 1
 
 if $USE_GO_TOOL; then
@@ -98,7 +98,7 @@ if $USE_GO_TOOL; then
 	./buildscript_${GOOS}_$GOARCH.sh
 
 	echo '# Building Go code.'
-	GOPATH="" go install -a all
+	go install -a std
 else
 	echo; echo; echo %%%% making pkg %%%%; echo
 	gomake -C pkg install

src/run.bash

@@ -34,7 +34,7 @@ if $rebuild; then
 	if $USE_GO_TOOL; then
 		echo
 		echo '# Package builds'
-		time GOPATH="" go install -a all
+		time go install -a std
 	else
 		(xcd pkg
 			gomake clean
@@ -46,7 +46,7 @@ fi
 if $USE_GO_TOOL; then
 	echo
 	echo '# Package tests'
-	time GOPATH="" go test all -short
+	time go test std -short
 else
 	(xcd pkg
 	gomake testshort