cmd/go: special case shared library name when passed "$prefix/..."

Before golang.org/cl/13921, "go install -buildmode=shared prefix/..." created a
file called "libprefix.so", which was obviously a problem when prefix was
something like "." or "../".  However, now it expands the ... into all the
matched packages, joins them with -, which can clearly be a very long name
indeed. Because I plan to build shared libraries for Ubuntu by running commands
exactly like "go install -buildmode=shared prefix/...", this special cases this
to produce the old behaviour (but de-relativises prefix first).

Fixes #13714

Change-Id: I4fd8d4934279f9a18cc70a13e4ef3e23f6abcb6e
Reviewed-on: https://go-review.googlesource.com/18114
Reviewed-by: Ian Lance Taylor <iant@golang.org>

src/cmd/go/build.go

@@ -520,11 +520,14 @@ func isMetaPackage(name string) bool {
 // Use arguments for special 'meta' packages:
 //	std --> libstd.so
 //	std cmd --> libstd,cmd.so
+// A single non-meta argument with trailing "/..." is special cased:
+//	foo/... --> libfoo.so
+//	(A relative path like "./..."  expands the "." first)
 // 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
+//	a/... b/... ---> liba/c,b/d.so - all matching import paths
 // Name parts are joined with ','.
 func libname(args []string, pkgs []*Package) (string, error) {
 	var libname string
@@ -544,9 +547,22 @@ func libname(args []string, pkgs []*Package) (string, error) {
 		}
 	}
 	if len(libname) == 0 { // non-meta packages only. use import paths
+		if len(args) == 1 && strings.HasSuffix(args[0], "/...") {
+			// Special case of "foo/..." as mentioned above.
+			arg := strings.TrimSuffix(args[0], "/...")
+			if build.IsLocalImport(arg) {
+				cwd, _ := os.Getwd()
+				bp, _ := buildContext.ImportDir(filepath.Join(cwd, arg), build.FindOnly)
+				if bp.ImportPath != "" && bp.ImportPath != "." {
+					arg = bp.ImportPath
+				}
+			}
+			appendName(strings.Replace(arg, "/", "-", -1))
+		} else {
 			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")
 	}

src/cmd/go/pkg_test.go

@@ -5,6 +5,9 @@
 package main
 
 import (
+	"io/ioutil"
+	"os"
+	"path/filepath"
 	"reflect"
 	"strings"
 	"testing"
@@ -90,73 +93,86 @@ func TestSharedLibName(t *testing.T) {
 		pkgs      []*Package
 		expected  string
 		expectErr bool
+		rootedAt  string
 	}{
 		{
-			[]string{"std"},
+			args:     []string{"std"},
-			[]*Package{},
+			pkgs:     []*Package{},
-			"std",
+			expected: "std",
-			false,
 		},
 		{
-			[]string{"std", "cmd"},
+			args:     []string{"std", "cmd"},
-			[]*Package{},
+			pkgs:     []*Package{},
-			"std,cmd",
+			expected: "std,cmd",
-			false,
 		},
 		{
-			[]string{},
+			args:     []string{},
-			[]*Package{&Package{ImportPath: "gopkg.in/somelib"}},
+			pkgs:     []*Package{&Package{ImportPath: "gopkg.in/somelib"}},
-			"gopkg.in-somelib",
+			expected: "gopkg.in-somelib",
-			false,
 		},
 		{
-			[]string{"./..."},
+			args:     []string{"./..."},
-			[]*Package{&Package{ImportPath: "somelib"}},
+			pkgs:     []*Package{&Package{ImportPath: "somelib"}},
-			"somelib",
+			expected: "somelib",
-			false,
+			rootedAt: "somelib",
 		},
 		{
-			[]string{"../somelib", "../somelib"},
+			args:     []string{"../somelib", "../somelib"},
-			[]*Package{&Package{ImportPath: "somelib"}},
+			pkgs:     []*Package{&Package{ImportPath: "somelib"}},
-			"somelib",
+			expected: "somelib",
-			false,
 		},
 		{
-			[]string{"../lib1", "../lib2"},
+			args:     []string{"../lib1", "../lib2"},
-			[]*Package{&Package{ImportPath: "gopkg.in/lib1"}, &Package{ImportPath: "gopkg.in/lib2"}},
+			pkgs:     []*Package{&Package{ImportPath: "gopkg.in/lib1"}, &Package{ImportPath: "gopkg.in/lib2"}},
-			"gopkg.in-lib1,gopkg.in-lib2",
+			expected: "gopkg.in-lib1,gopkg.in-lib2",
-			false,
 		},
 		{
-			[]string{"./..."},
+			args: []string{"./..."},
-			[]*Package{
+			pkgs: []*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",
+			expected: "gopkg.in",
-			false,
+			rootedAt: "gopkg.in",
 		},
 		{
-			[]string{"std", "../lib2"},
+			args:      []string{"std", "../lib2"},
-			[]*Package{},
+			pkgs:      []*Package{},
-			"",
+			expectErr: true,
-			true,
 		},
 		{
-			[]string{"all", "./"},
+			args:      []string{"all", "./"},
-			[]*Package{},
+			pkgs:      []*Package{},
-			"",
+			expectErr: true,
-			true,
 		},
 		{
-			[]string{"cmd", "fmt"},
+			args:      []string{"cmd", "fmt"},
-			[]*Package{},
+			pkgs:      []*Package{},
-			"",
+			expectErr: true,
-			true,
 		},
 	}
 	for _, data := range testData {
+		func() {
+			if data.rootedAt != "" {
+				tmpGopath, err := ioutil.TempDir("", "gopath")
+				if err != nil {
+					t.Fatal(err)
+				}
+				oldGopath := buildContext.GOPATH
+				defer func() {
+					os.RemoveAll(tmpGopath)
+					buildContext.GOPATH = oldGopath
+					os.Chdir(cwd)
+				}()
+				root := filepath.Join(tmpGopath, "src", data.rootedAt)
+				err = os.MkdirAll(root, 0755)
+				if err != nil {
+					t.Fatal(err)
+				}
+				buildContext.GOPATH = tmpGopath
+				os.Chdir(root)
+			}
 			computed, err := libname(data.args, data.pkgs)
 			if err != nil {
 				if !data.expectErr {
@@ -170,5 +186,6 @@ func TestSharedLibName(t *testing.T) {
 					t.Errorf("libname returned %q, expected %q", computed, expected)
 				}
 			}
+		}()
 	}
 }