go/build: handle cgo, //build comments

R=adg
CC=golang-dev
https://golang.org/cl/5018044

src/cmd/goinstall/main.go

@@ -13,7 +13,7 @@ import (
 	"go/token"
 	"io/ioutil"
 	"os"
-	"path/filepath"
+	"path/filepath" // use for file system paths
 	"regexp"
 	"runtime"
 	"strings"
@@ -190,7 +190,7 @@ func install(pkg, parent string) {
 	}()
 
 	// Don't allow trailing '/'
-	if _, f := filepath.Split(pkg); f == "" {
+	if strings.HasSuffix(pkg, "/") {
 		errorf("%s should not have trailing '/'\n", pkg)
 		return
 	}
@@ -225,16 +225,17 @@ func install(pkg, parent string) {
 		terrorf(tree, "%s: %v\n", pkg, err)
 		return
 	}
-	dir := filepath.Join(tree.SrcDir(), pkg)
+	dir := filepath.Join(tree.SrcDir(), filepath.FromSlash(pkg))
 
 	// Install prerequisites.
-	dirInfo, err := build.ScanDir(dir, parent == "")
+	dirInfo, err := build.ScanDir(dir)
 	if err != nil {
 		terrorf(tree, "%s: %v\n", pkg, err)
 		return
 	}
-	if len(dirInfo.GoFiles)+len(dirInfo.CgoFiles) == 0 {
-		terrorf(tree, "%s: package has no files\n", pkg)
+	// We reserve package main to identify commands.
+	if parent != "" && dirInfo.Package == "main" {
+		terrorf(tree, "%s: found only package main in %s; cannot import", pkg, dir)
 		return
 	}
 	for _, p := range dirInfo.Imports {

src/cmd/goinstall/make.go

@@ -10,7 +10,7 @@ import (
 	"bytes"
 	"go/build"
 	"os"
-	"path/filepath"
+	"path" // use for import paths
 	"strings"
 	"template"
 )
@@ -44,10 +44,10 @@ func makeMakefile(dir, pkg string, tree *build.Tree, isCmd bool) ([]byte, os.Err
 	targDir := tree.PkgDir()
 	if isCmd {
 		// use the last part of the package name for targ
-		_, targ = filepath.Split(pkg)
+		_, targ = path.Split(pkg)
 		targDir = tree.BinDir()
 	}
-	dirInfo, err := build.ScanDir(dir, isCmd)
+	dirInfo, err := build.ScanDir(dir)
 	if err != nil {
 		return nil, err
 	}

src/cmd/gotest/gotest.go

@@ -165,7 +165,7 @@ func setEnvironment() {
 func getTestFileNames() {
 	names := fileNames
 	if len(names) == 0 {
-		info, err := build.ScanDir(".", true)
+		info, err := build.ScanDir(".")
 		if err != nil {
 			Fatalf("scanning directory: %v", err)
 		}

src/pkg/go/build/build_test.go

@@ -27,7 +27,7 @@ var buildPkgs = []struct {
 		&DirInfo{
 			GoFiles:      []string{"pkgtest.go"},
 			SFiles:       []string{"sqrt_" + runtime.GOARCH + ".s"},
-			PkgName:      "pkgtest",
+			Package:      "pkgtest",
 			Imports:      []string{"os"},
 			TestImports:  []string{"fmt", "pkgtest"},
 			TestGoFiles:  sortstr([]string{"sqrt_test.go", "sqrt_" + runtime.GOARCH + "_test.go"}),
@@ -38,17 +38,19 @@ var buildPkgs = []struct {
 		"go/build/cmdtest",
 		&DirInfo{
 			GoFiles: []string{"main.go"},
-			PkgName: "main",
+			Package: "main",
 			Imports: []string{"go/build/pkgtest"},
 		},
 	},
 	{
 		"go/build/cgotest",
 		&DirInfo{
-			CgoFiles: []string{"cgotest.go"},
-			CFiles:   []string{"cgotest.c"},
-			Imports:  []string{"C", "unsafe"},
-			PkgName:  "cgotest",
+			CgoFiles:     []string{"cgotest.go"},
+			CFiles:       []string{"cgotest.c"},
+			Imports:      []string{"C", "unsafe"},
+			Package:      "cgotest",
+			CgoLDFLAGS:   []string{"-lregexp"},
+			CgoPkgConfig: []string{"cairo", "moscow"},
 		},
 	},
 }
@@ -56,11 +58,11 @@ var buildPkgs = []struct {
 const cmdtestOutput = "3"
 
 func TestBuild(t *testing.T) {
+	var ctxt = Context{GOOS: "darwin", GOARCH: "amd64"}
 	for _, tt := range buildPkgs {
 		tree := Path[0] // Goroot
 		dir := filepath.Join(tree.SrcDir(), tt.dir)
-
-		info, err := ScanDir(dir, true)
+		info, err := ctxt.ScanDir(dir)
 		if err != nil {
 			t.Errorf("ScanDir(%#q): %v", tt.dir, err)
 			continue
@@ -70,6 +72,13 @@ func TestBuild(t *testing.T) {
 			continue
 		}
 
+		if tt.dir == "go/build/cgotest" {
+			// Don't actually run cgo.
+			// Among other things our test depends
+			// on pkg-config, which is not present on all systems.
+			continue
+		}
+
 		s, err := Build(tree, tt.dir, info)
 		if err != nil {
 			t.Errorf("Build(%#q): %v", tt.dir, err)

src/pkg/go/build/cgotest/cgotest.go

@@ -6,6 +6,9 @@ package cgotest
 
 /*
 char* greeting = "hello, world";
+#cgo darwin/amd64 LDFLAGS: -lregexp
+#cgo linux CFLAGS: -m32
+#cgo pkg-config: cairo moscow
 */
 // #include "cgotest.h"
 import "C"

src/pkg/go/build/syslist_test.go

@@ -55,8 +55,8 @@ var tests = []GoodFileTest{
 
 func TestGoodOSArch(t *testing.T) {
 	for _, test := range tests {
-		if DefaultContext.goodOSArch(test.name) != test.result {
-			t.Fatalf("goodOSArch(%q) != %v", test.name, test.result)
+		if DefaultContext.goodOSArchFile(test.name) != test.result {
+			t.Fatalf("goodOSArchFile(%q) != %v", test.name, test.result)
 		}
 	}
 }