cmd/go: fix bad shared lib name with buildmode=shared

Use import paths of packages to build a shared lib name.
Use arguments for meta-packages 'std', 'cmd', and 'all'.

Fixes #12236

Change-Id: If274d63301686ef34e198287eb012f9062541ea0
Reviewed-on: https://go-review.googlesource.com/13921Reviewed-by: Ian Lance Taylor <iant@golang.org>
Run-TryBot: Ian Lance Taylor <iant@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>

src/cmd/go/build.go

@@ -480,7 +480,12 @@ func runBuild(cmd *Command, args []string) {
 
 	var a *action
 	if buildBuildmode == "shared" {
-		a = b.libaction(libname(args), pkgsFilter(packages(args)), modeBuild, depMode)
+		pkgs := pkgsFilter(packages(args))
+		if libName, err := libname(args, pkgs); err != nil {
+			fatalf("%s", err.Error())
+		} else {
+			a = b.libaction(libName, pkgs, modeBuild, depMode)
+		}
 	} else {
 		a = &action{}
 		for _, p := range pkgsFilter(packages(args)) {
@@ -504,28 +509,49 @@ See also: go build, go get, go clean.
 	`,
 }
 
+// isMetaPackage checks if name is a reserved package name that expands to multiple packages
+func isMetaPackage(name string) bool {
+	return name == "std" || name == "cmd" || name == "all"
+}
+
 // libname returns the filename to use for the shared library when using
 // -buildmode=shared.  The rules we use are:
-//  1) Drop any trailing "/..."s if present
-//  2) Change / to -
-//  3) Join arguments with ,
-// So std -> libstd.so
-//    a b/... -> liba,b.so
-//    gopkg.in/tomb.v2 -> libgopkg.in-tomb.v2.so
-func libname(args []string) string {
+// Use arguments for special 'meta' packages:
+//	std --> libstd.so
+//	std cmd --> libstd,cmd.so
+// Use import paths for other cases, changing '/' to '-':
+//	somelib --> libsubdir-somelib.so
+//	./ or ../ --> libsubdir-somelib.so
+//	gopkg.in/tomb.v2 -> libgopkg.in-tomb.v2.so
+//	./... ---> libpkg1,pkg2.so - subset of all import paths
+// Name parts are joined with ','.
+func libname(args []string, pkgs []*Package) (string, error) {
 	var libname string
-	for _, arg := range args {
-		arg = strings.TrimSuffix(arg, "/...")
-		arg = strings.Replace(arg, "/", "-", -1)
+	appendName := func(arg string) {
 		if libname == "" {
 			libname = arg
 		} else {
 			libname += "," + arg
 		}
 	}
+	var haveNonMeta bool
+	for _, arg := range args {
+		if isMetaPackage(arg) {
+			appendName(arg)
+		} else {
+			haveNonMeta = true
+		}
+	}
+	if len(libname) == 0 { // non-meta packages only. use import paths
+		for _, pkg := range pkgs {
+			appendName(strings.Replace(pkg.ImportPath, "/", "-", -1))
+		}
+	} else if haveNonMeta { // have both meta package and a non-meta one
+		return "", errors.New("mixing of meta and non-meta packages is not allowed")
+	}
 	// TODO(mwhudson): Needs to change for platforms that use different naming
 	// conventions...
-	return "lib" + libname + ".so"
+	return "lib" + libname + ".so", nil
 }
 
 func runInstall(cmd *Command, args []string) {
@@ -558,7 +584,11 @@ func runInstall(cmd *Command, args []string) {
 	b.init()
 	var a *action
 	if buildBuildmode == "shared" {
-		a = b.libaction(libname(args), pkgs, modeInstall, modeInstall)
+		if libName, err := libname(args, pkgs); err != nil {
+			fatalf("%s", err.Error())
+		} else {
+			a = b.libaction(libName, pkgs, modeInstall, modeInstall)
+		}
 	} else {
 		a = &action{}
 		var tools []*action

src/cmd/go/main.go

@@ -353,7 +353,7 @@ func importPathsNoDotExpansion(args []string) []string {
 		} else {
 			a = path.Clean(a)
 		}
-		if a == "all" || a == "std" || a == "cmd" {
+		if isMetaPackage(a) {
 			out = append(out, allPackages(a)...)
 			continue
 		}
@@ -554,7 +554,7 @@ func allPackages(pattern string) []string {
 func matchPackages(pattern string) []string {
 	match := func(string) bool { return true }
 	treeCanMatch := func(string) bool { return true }
-	if pattern != "all" && pattern != "std" && pattern != "cmd" {
+	if !isMetaPackage(pattern) {
 		match = matchPattern(pattern)
 		treeCanMatch = treeCanMatchPattern(pattern)
 	}

src/cmd/go/pkg_test.go

@@ -71,3 +71,95 @@ func TestParseMetaGoImports(t *testing.T) {
 		}
 	}
 }
+
+func TestSharedLibName(t *testing.T) {
+	// TODO(avdva) - make these values platform-specific
+	prefix := "lib"
+	suffix := ".so"
+	testData := []struct {
+		args      []string
+		pkgs      []*Package
+		expected  string
+		expectErr bool
+	}{
+		{
+			[]string{"std"},
+			[]*Package{},
+			"std",
+			false,
+		},
+		{
+			[]string{"std", "cmd"},
+			[]*Package{},
+			"std,cmd",
+			false,
+		},
+		{
+			[]string{},
+			[]*Package{&Package{ImportPath: "gopkg.in/somelib"}},
+			"gopkg.in-somelib",
+			false,
+		},
+		{
+			[]string{"./..."},
+			[]*Package{&Package{ImportPath: "somelib"}},
+			"somelib",
+			false,
+		},
+		{
+			[]string{"../somelib", "../somelib"},
+			[]*Package{&Package{ImportPath: "somelib"}},
+			"somelib",
+			false,
+		},
+		{
+			[]string{"../lib1", "../lib2"},
+			[]*Package{&Package{ImportPath: "gopkg.in/lib1"}, &Package{ImportPath: "gopkg.in/lib2"}},
+			"gopkg.in-lib1,gopkg.in-lib2",
+			false,
+		},
+		{
+			[]string{"./..."},
+			[]*Package{
+				&Package{ImportPath: "gopkg.in/dir/lib1"},
+				&Package{ImportPath: "gopkg.in/lib2"},
+				&Package{ImportPath: "gopkg.in/lib3"},
+			},
+			"gopkg.in-dir-lib1,gopkg.in-lib2,gopkg.in-lib3",
+			false,
+		},
+		{
+			[]string{"std", "../lib2"},
+			[]*Package{},
+			"",
+			true,
+		},
+		{
+			[]string{"all", "./"},
+			[]*Package{},
+			"",
+			true,
+		},
+		{
+			[]string{"cmd", "fmt"},
+			[]*Package{},
+			"",
+			true,
+		},
+	}
+	for _, data := range testData {
+		computed, err := libname(data.args, data.pkgs)
+		if err != nil {
+			if !data.expectErr {
+				t.Errorf("libname returned an error %q, expected a name", err.Error())
+			}
+		} else if data.expectErr {
+			t.Errorf("libname returned %q, expected an error", computed)
+		} else {
+			expected := prefix + data.expected + suffix
+			if expected != computed {
+				t.Errorf("libname returned %q, expected %q", computed, expected)
+			}
+		}
+	}
+}