Imported Upstream version 2012.03.22upstream-weekly/2012.03.22

18 files changed, 1156 insertions, 164 deletions

diff --git a/src/pkg/go/build/Makefile b/src/pkg/go/build/Makefile
deleted file mode 100644
index 3bb3912cb..000000000
--- a/src/pkg/go/build/Makefile
+++ /dev/null
@@ -1,11 +0,0 @@
-# Copyright 2009 The Go Authors. All rights reserved.
-# Use of this source code is governed by a BSD-style
-# license that can be found in the LICENSE file.
-
-syslist.go: ../../../Make.inc Makefile
-	echo '// Generated automatically by make.' >$@
-	echo >>$@
-	echo 'package build' >>$@
-	echo >>$@
-	echo 'const goosList = "$(GOOS_LIST)"' >>$@
-	echo 'const goarchList = "$(GOARCH_LIST)"' >>$@
diff --git a/src/pkg/go/build/build.go b/src/pkg/go/build/build.go
index eece76105..d113dc135 100644
--- a/src/pkg/go/build/build.go
+++ b/src/pkg/go/build/build.go
@@ -34,7 +34,7 @@ type Context struct {
 	CgoEnabled  bool     // whether cgo can be used
 	BuildTags   []string // additional tags to recognize in +build lines
 	UseAllFiles bool     // use files regardless of +build lines, file names
-	Gccgo       bool     // assume use of gccgo when computing object paths
+	Compiler    string   // compiler to assume when computing target paths
 
 	// By default, Import uses the operating system's file system calls
 	// to read directories and files.  To read from other sources,
@@ -210,6 +210,7 @@ func (ctxt *Context) SrcDirs() []string {
 // if set, or else the compiled code's GOARCH, GOOS, and GOROOT.
 var Default Context = defaultContext()
 
+// This list is also known to ../../../cmd/dist/build.c.
 var cgoEnabled = map[string]bool{
 	"darwin/386":    true,
 	"darwin/amd64":  true,
@@ -228,6 +229,7 @@ func defaultContext() Context {
 	c.GOOS = envOr("GOOS", runtime.GOOS)
 	c.GOROOT = runtime.GOROOT()
 	c.GOPATH = envOr("GOPATH", "")
+	c.Compiler = runtime.Compiler
 
 	switch os.Getenv("CGO_ENABLED") {
 	case "1":
@@ -277,11 +279,12 @@ type Package struct {
 	PkgObj     string // installed .a file
 
 	// Source files
-	GoFiles  []string // .go source files (excluding CgoFiles, TestGoFiles, XTestGoFiles)
-	CgoFiles []string // .go source files that import "C"
-	CFiles   []string // .c source files
-	HFiles   []string // .h source files
-	SFiles   []string // .s source files
+	GoFiles   []string // .go source files (excluding CgoFiles, TestGoFiles, XTestGoFiles)
+	CgoFiles  []string // .go source files that import "C"
+	CFiles    []string // .c source files
+	HFiles    []string // .h source files
+	SFiles    []string // .s source files
+	SysoFiles []string // .syso system object files to add to archive
 
 	// Cgo directives
 	CgoPkgConfig []string // Cgo pkg-config directives
@@ -314,42 +317,58 @@ func (ctxt *Context) ImportDir(dir string, mode ImportMode) (*Package, error) {
 	return ctxt.Import(".", dir, mode)
 }
 
+// NoGoError is the error used by Import to describe a directory
+// containing no Go source files.
+type NoGoError struct {
+	Dir string
+}
+
+func (e *NoGoError) Error() string {
+	return "no Go source files in " + e.Dir
+}
+
 // Import returns details about the Go package named by the import path,
-// interpreting local import paths relative to the src directory.  If the path
-// is a local import path naming a package that can be imported using a
-// standard import path, the returned package will set p.ImportPath to
-// that path.
+// interpreting local import paths relative to the srcDir directory.
+// If the path is a local import path naming a package that can be imported
+// using a standard import path, the returned package will set p.ImportPath
+// to that path.
 //
 // In the directory containing the package, .go, .c, .h, and .s files are
 // considered part of the package except for:
 //
 //	- .go files in package documentation
-//	- files starting with _ or .
+//	- files starting with _ or . (likely editor temporary files)
 //	- files with build constraints not satisfied by the context
 //
 // If an error occurs, Import returns a non-nil error also returns a non-nil
 // *Package containing partial information.
 //
-func (ctxt *Context) Import(path string, src string, mode ImportMode) (*Package, error) {
+func (ctxt *Context) Import(path string, srcDir string, mode ImportMode) (*Package, error) {
 	p := &Package{
 		ImportPath: path,
 	}
 
 	var pkga string
-	if ctxt.Gccgo {
+	var pkgerr error
+	switch ctxt.Compiler {
+	case "gccgo":
 		dir, elem := pathpkg.Split(p.ImportPath)
 		pkga = "pkg/gccgo/" + dir + "lib" + elem + ".a"
-	} else {
+	case "gc":
 		pkga = "pkg/" + ctxt.GOOS + "_" + ctxt.GOARCH + "/" + p.ImportPath + ".a"
+	default:
+		// Save error for end of function.
+		pkgerr = fmt.Errorf("import %q: unknown compiler %q", path, ctxt.Compiler)
 	}
 
 	binaryOnly := false
 	if IsLocalImport(path) {
-		if src == "" {
+		pkga = "" // local imports have no installed path
+		if srcDir == "" {
 			return p, fmt.Errorf("import %q: import relative to unknown directory", path)
 		}
 		if !ctxt.isAbsPath(path) {
-			p.Dir = ctxt.joinPath(src, path)
+			p.Dir = ctxt.joinPath(srcDir, path)
 		}
 		// Determine canonical import path, if any.
 		if ctxt.GOROOT != "" {
@@ -396,7 +415,7 @@ func (ctxt *Context) Import(path string, src string, mode ImportMode) (*Package,
 		if ctxt.GOROOT != "" {
 			dir := ctxt.joinPath(ctxt.GOROOT, "src", "pkg", path)
 			isDir := ctxt.isDir(dir)
-			binaryOnly = !isDir && mode&AllowBinary != 0 && ctxt.isFile(ctxt.joinPath(ctxt.GOROOT, pkga))
+			binaryOnly = !isDir && mode&AllowBinary != 0 && pkga != "" && ctxt.isFile(ctxt.joinPath(ctxt.GOROOT, pkga))
 			if isDir || binaryOnly {
 				p.Dir = dir
 				p.Goroot = true
@@ -407,7 +426,7 @@ func (ctxt *Context) Import(path string, src string, mode ImportMode) (*Package,
 		for _, root := range ctxt.gopath() {
 			dir := ctxt.joinPath(root, "src", path)
 			isDir := ctxt.isDir(dir)
-			binaryOnly = !isDir && mode&AllowBinary != 0 && ctxt.isFile(ctxt.joinPath(root, pkga))
+			binaryOnly = !isDir && mode&AllowBinary != 0 && pkga != "" && ctxt.isFile(ctxt.joinPath(root, pkga))
 			if isDir || binaryOnly {
 				p.Dir = dir
 				p.Root = root
@@ -426,14 +445,16 @@ Found:
 		}
 		p.PkgRoot = ctxt.joinPath(p.Root, "pkg")
 		p.BinDir = ctxt.joinPath(p.Root, "bin")
-		p.PkgObj = ctxt.joinPath(p.Root, pkga)
+		if pkga != "" {
+			p.PkgObj = ctxt.joinPath(p.Root, pkga)
+		}
 	}
 
 	if mode&FindOnly != 0 {
-		return p, nil
+		return p, pkgerr
 	}
 	if binaryOnly && (mode&AllowBinary) != 0 {
-		return p, nil
+		return p, pkgerr
 	}
 
 	dirs, err := ctxt.readDir(p.Dir)
@@ -467,7 +488,13 @@ Found:
 		ext := name[i:]
 		switch ext {
 		case ".go", ".c", ".s", ".h", ".S":
-			// tentatively okay
+			// tentatively okay - read to make sure
+		case ".syso":
+			// binary objects to add to package archive
+			// Likely of the form foo_windows.syso, but
+			// the name was vetted above with goodOSArchFile.
+			p.SysoFiles = append(p.SysoFiles, name)
+			continue
 		default:
 			// skip
 			continue
@@ -586,7 +613,7 @@ Found:
 		}
 	}
 	if p.Name == "" {
-		return p, fmt.Errorf("no Go source files in %s", p.Dir)
+		return p, &NoGoError{p.Dir}
 	}
 
 	p.Imports, p.ImportPos = cleanImports(imported)
@@ -601,7 +628,7 @@ Found:
 		sort.Strings(p.SFiles)
 	}
 
-	return p, nil
+	return p, pkgerr
 }
 
 func cleanImports(m map[string][]token.Position) ([]string, map[string][]token.Position) {
@@ -614,8 +641,8 @@ func cleanImports(m map[string][]token.Position) ([]string, map[string][]token.P
 }
 
 // Import is shorthand for Default.Import.
-func Import(path, src string, mode ImportMode) (*Package, error) {
-	return Default.Import(path, src, mode)
+func Import(path, srcDir string, mode ImportMode) (*Package, error) {
+	return Default.Import(path, srcDir, mode)
 }
 
 // ImportDir is shorthand for Default.ImportDir.
@@ -848,7 +875,7 @@ func splitQuoted(s string) (r []string, err error) {
 //	!cgo (if cgo is disabled)
 //	tag (if tag is listed in ctxt.BuildTags)
 //	!tag (if tag is not listed in ctxt.BuildTags)
-//	a slash-separated list of any of these
+//	a comma-separated list of any of these
 //
 func (ctxt *Context) match(name string) bool {
 	if name == "" {
@@ -862,11 +889,11 @@ func (ctxt *Context) match(name string) bool {
 		return false
 	}
 	if strings.HasPrefix(name, "!") { // negation
-		return !ctxt.match(name[1:])
+		return len(name) > 1 && !ctxt.match(name[1:])
 	}
 
 	// Tags must be letters, digits, underscores.
-	// Unlike in Go identifiers, all digits is fine (e.g., "386").
+	// Unlike in Go identifiers, all digits are fine (e.g., "386").
 	for _, c := range name {
 		if !unicode.IsLetter(c) && !unicode.IsDigit(c) && c != '_' {
 			return false
diff --git a/src/pkg/go/build/build_test.go b/src/pkg/go/build/build_test.go
index 06b8b0e94..560ebad5c 100644
--- a/src/pkg/go/build/build_test.go
+++ b/src/pkg/go/build/build_test.go
@@ -36,6 +36,7 @@ func TestMatch(t *testing.T) {
 	nomatch(runtime.GOOS + "," + runtime.GOARCH + ",!foo")
 	match(runtime.GOOS + "," + runtime.GOARCH + ",!bar")
 	nomatch(runtime.GOOS + "," + runtime.GOARCH + ",bar")
+	nomatch("!")
 }
 
 func TestDotSlashImport(t *testing.T) {
diff --git a/src/pkg/go/build/deps_test.go b/src/pkg/go/build/deps_test.go
new file mode 100644
index 000000000..4e9f32a03
--- /dev/null
+++ b/src/pkg/go/build/deps_test.go
@@ -0,0 +1,424 @@
+// Copyright 2012 The Go Authors.  All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+// This file exercises the import parser but also checks that
+// some low-level packages do not have new dependencies added.
+
+package build_test
+
+import (
+	"go/build"
+	"sort"
+	"testing"
+)
+
+// pkgDeps defines the expected dependencies between packages in
+// the Go source tree.  It is a statement of policy.
+// Changes should not be made to this map without prior discussion.
+//
+// The map contains two kinds of entries:
+// 1) Lower-case keys are standard import paths and list the
+// allowed imports in that package.
+// 2) Upper-case keys define aliases for package sets, which can then
+// be used as dependencies by other rules.
+//
+// DO NOT CHANGE THIS DATA TO FIX BUILDS.
+// 
+var pkgDeps = map[string][]string{
+	// L0 is the lowest level, core, nearly unavoidable packages.
+	"errors":      {},
+	"io":          {"errors", "sync"},
+	"runtime":     {"unsafe"},
+	"sync":        {"sync/atomic"},
+	"sync/atomic": {"unsafe"},
+	"unsafe":      {},
+
+	"L0": {
+		"errors",
+		"io",
+		"runtime",
+		"sync",
+		"sync/atomic",
+		"unsafe",
+	},
+
+	// L1 adds simple functions and strings processing,
+	// but not Unicode tables.
+	"math":          {"unsafe"},
+	"math/cmplx":    {"math"},
+	"math/rand":     {"L0", "math"},
+	"sort":          {"math"},
+	"strconv":       {"L0", "unicode/utf8", "math"},
+	"unicode/utf16": {},
+	"unicode/utf8":  {},
+
+	"L1": {
+		"L0",
+		"math",
+		"math/cmplx",
+		"math/rand",
+		"sort",
+		"strconv",
+		"unicode/utf16",
+		"unicode/utf8",
+	},
+
+	// L2 adds Unicode and strings processing.
+	"bufio":   {"L0", "unicode/utf8", "bytes"},
+	"bytes":   {"L0", "unicode", "unicode/utf8"},
+	"path":    {"L0", "unicode/utf8", "strings"},
+	"strings": {"L0", "unicode", "unicode/utf8"},
+	"unicode": {},
+
+	"L2": {
+		"L1",
+		"bufio",
+		"bytes",
+		"path",
+		"strings",
+		"unicode",
+	},
+
+	// L3 adds reflection and some basic utility packages
+	// and interface definitions, but nothing that makes
+	// system calls.
+	"crypto":          {"L2", "hash"}, // interfaces
+	"crypto/cipher":   {"L2"},         // interfaces
+	"encoding/base32": {"L2"},
+	"encoding/base64": {"L2"},
+	"encoding/binary": {"L2", "reflect"},
+	"hash":            {"L2"}, // interfaces
+	"hash/adler32":    {"L2", "hash"},
+	"hash/crc32":      {"L2", "hash"},
+	"hash/crc64":      {"L2", "hash"},
+	"hash/fnv":        {"L2", "hash"},
+	"image":           {"L2", "image/color"}, // interfaces
+	"image/color":     {"L2"},                // interfaces
+	"reflect":         {"L2"},
+
+	"L3": {
+		"L2",
+		"crypto",
+		"crypto/cipher",
+		"encoding/base32",
+		"encoding/base64",
+		"encoding/binary",
+		"hash",
+		"hash/adler32",
+		"hash/crc32",
+		"hash/crc64",
+		"hash/fnv",
+		"image",
+		"image/color",
+		"reflect",
+	},
+
+	// End of linear dependency definitions.
+
+	// Operating system access.
+	"syscall":       {"L0", "unicode/utf16"},
+	"time":          {"L0", "syscall"},
+	"os":            {"L1", "os", "syscall", "time"},
+	"path/filepath": {"L2", "os", "syscall"},
+	"io/ioutil":     {"L2", "os", "path/filepath", "time"},
+	"os/exec":       {"L2", "os", "syscall"},
+	"os/signal":     {"L2", "os", "syscall"},
+
+	// OS enables basic operating system functionality,
+	// but not direct use of package syscall, nor os/signal.
+	"OS": {
+		"io/ioutil",
+		"os",
+		"os/exec",
+		"path/filepath",
+		"time",
+	},
+
+	// Formatted I/O: few dependencies (L1) but we must add reflect.
+	"fmt": {"L1", "os", "reflect"},
+	"log": {"L1", "os", "fmt", "time"},
+
+	// Packages used by testing must be low-level (L2+fmt).
+	"regexp":         {"L2", "regexp/syntax"},
+	"regexp/syntax":  {"L2"},
+	"runtime/debug":  {"L2", "fmt", "io/ioutil", "os"},
+	"runtime/pprof":  {"L2", "fmt", "text/tabwriter"},
+	"text/tabwriter": {"L2"},
+
+	"testing":        {"L2", "flag", "fmt", "os", "runtime/pprof", "time"},
+	"testing/iotest": {"L2", "log"},
+	"testing/quick":  {"L2", "flag", "fmt", "reflect"},
+
+	// L4 is defined as L3+fmt+log+time, because in general once
+	// you're using L3 packages, use of fmt, log, or time is not a big deal.
+	"L4": {
+		"L3",
+		"fmt",
+		"log",
+		"time",
+	},
+
+	// Go parser.
+	"go/ast":     {"L4", "OS", "go/scanner", "go/token"},
+	"go/doc":     {"L4", "go/ast", "go/token", "regexp", "text/template"},
+	"go/parser":  {"L4", "OS", "go/ast", "go/scanner", "go/token"},
+	"go/printer": {"L4", "OS", "go/ast", "go/scanner", "go/token", "text/tabwriter"},
+	"go/scanner": {"L4", "OS", "go/token"},
+	"go/token":   {"L4"},
+
+	"GOPARSER": {
+		"go/ast",
+		"go/doc",
+		"go/parser",
+		"go/printer",
+		"go/scanner",
+		"go/token",
+	},
+
+	// One of a kind.
+	"archive/tar":         {"L4", "OS"},
+	"archive/zip":         {"L4", "OS", "compress/flate"},
+	"compress/bzip2":      {"L4"},
+	"compress/flate":      {"L4"},
+	"compress/gzip":       {"L4", "compress/flate"},
+	"compress/lzw":        {"L4"},
+	"compress/zlib":       {"L4", "compress/flate"},
+	"database/sql":        {"L4", "database/sql/driver"},
+	"database/sql/driver": {"L4", "time"},
+	"debug/dwarf":         {"L4"},
+	"debug/elf":           {"L4", "OS", "debug/dwarf"},
+	"debug/gosym":         {"L4"},
+	"debug/macho":         {"L4", "OS", "debug/dwarf"},
+	"debug/pe":            {"L4", "OS", "debug/dwarf"},
+	"encoding/ascii85":    {"L4"},
+	"encoding/asn1":       {"L4", "math/big"},
+	"encoding/csv":        {"L4"},
+	"encoding/gob":        {"L4", "OS"},
+	"encoding/hex":        {"L4"},
+	"encoding/json":       {"L4"},
+	"encoding/pem":        {"L4"},
+	"encoding/xml":        {"L4"},
+	"flag":                {"L4", "OS"},
+	"go/build":            {"L4", "OS", "GOPARSER"},
+	"html":                {"L4"},
+	"image/draw":          {"L4"},
+	"image/gif":           {"L4", "compress/lzw"},
+	"image/jpeg":          {"L4"},
+	"image/png":           {"L4", "compress/zlib"},
+	"index/suffixarray":   {"L4", "regexp"},
+	"math/big":            {"L4"},
+	"mime":                {"L4", "OS", "syscall"},
+	"net/url":             {"L4"},
+	"text/scanner":        {"L4", "OS"},
+	"text/template/parse": {"L4"},
+
+	"html/template": {
+		"L4", "OS", "encoding/json", "html", "text/template",
+		"text/template/parse",
+	},
+	"text/template": {
+		"L4", "OS", "net/url", "text/template/parse",
+	},
+
+	// Cgo.
+	"runtime/cgo": {"L0", "C"},
+	"CGO":         {"C", "runtime/cgo"},
+
+	// Fake entry to satisfy the pseudo-import "C"
+	// that shows up in programs that use cgo.
+	"C": {},
+
+	"os/user": {"L4", "CGO", "syscall"},
+
+	// Basic networking.
+	// Because net must be used by any package that wants to
+	// do networking portably, it must have a small dependency set: just L1+basic os.
+	"net": {"L1", "CGO", "os", "syscall", "time"},
+
+	// NET enables use of basic network-related packages.
+	"NET": {
+		"net",
+		"mime",
+		"net/textproto",
+		"net/url",
+	},
+
+	// Uses of networking.
+	"log/syslog":    {"L4", "OS", "net"},
+	"net/mail":      {"L4", "NET", "OS"},
+	"net/textproto": {"L4", "OS", "net"},
+
+	// Core crypto.
+	"crypto/aes":    {"L3"},
+	"crypto/des":    {"L3"},
+	"crypto/hmac":   {"L3"},
+	"crypto/md5":    {"L3"},
+	"crypto/rc4":    {"L3"},
+	"crypto/sha1":   {"L3"},
+	"crypto/sha256": {"L3"},
+	"crypto/sha512": {"L3"},
+	"crypto/subtle": {"L3"},
+
+	"CRYPTO": {
+		"crypto/aes",
+		"crypto/des",
+		"crypto/hmac",
+		"crypto/md5",
+		"crypto/rc4",
+		"crypto/sha1",
+		"crypto/sha256",
+		"crypto/sha512",
+		"crypto/subtle",
+	},
+
+	// Random byte, number generation.
+	// This would be part of core crypto except that it imports
+	// math/big, which imports fmt.
+	"crypto/rand": {"L4", "CRYPTO", "OS", "math/big", "syscall"},
+
+	// Mathematical crypto: dependencies on fmt (L4) and math/big.
+	// We could avoid some of the fmt, but math/big imports fmt anyway.
+	"crypto/dsa":      {"L4", "CRYPTO", "math/big"},
+	"crypto/ecdsa":    {"L4", "CRYPTO", "crypto/elliptic", "math/big"},
+	"crypto/elliptic": {"L4", "CRYPTO", "math/big"},
+	"crypto/rsa":      {"L4", "CRYPTO", "crypto/rand", "math/big"},
+
+	"CRYPTO-MATH": {
+		"CRYPTO",
+		"crypto/dsa",
+		"crypto/ecdsa",
+		"crypto/elliptic",
+		"crypto/rand",
+		"crypto/rsa",
+		"encoding/asn1",
+		"math/big",
+	},
+
+	// SSL/TLS.
+	"crypto/tls": {
+		"L4", "CRYPTO-MATH", "CGO", "OS",
+		"crypto/x509", "encoding/pem", "net", "syscall",
+	},
+	"crypto/x509":      {"L4", "CRYPTO-MATH", "OS", "CGO", "crypto/x509/pkix", "encoding/pem", "syscall"},
+	"crypto/x509/pkix": {"L4", "CRYPTO-MATH"},
+
+	// Simple net+crypto-aware packages.
+	"mime/multipart": {"L4", "OS", "mime", "crypto/rand", "net/textproto"},
+	"net/smtp":       {"L4", "CRYPTO", "NET", "crypto/tls"},
+
+	// HTTP, kingpin of dependencies.
+	"net/http": {
+		"L4", "NET", "OS",
+		"compress/gzip", "crypto/tls", "mime/multipart", "runtime/debug",
+	},
+
+	// HTTP-using packages.
+	"expvar":            {"L4", "OS", "encoding/json", "net/http"},
+	"net/http/cgi":      {"L4", "NET", "OS", "crypto/tls", "net/http", "regexp"},
+	"net/http/fcgi":     {"L4", "NET", "OS", "net/http", "net/http/cgi"},
+	"net/http/httptest": {"L4", "NET", "OS", "crypto/tls", "flag", "net/http"},
+	"net/http/httputil": {"L4", "NET", "OS", "net/http"},
+	"net/http/pprof":    {"L4", "OS", "html/template", "net/http", "runtime/pprof"},
+	"net/rpc":           {"L4", "NET", "encoding/gob", "net/http", "text/template"},
+	"net/rpc/jsonrpc":   {"L4", "NET", "encoding/json", "net/rpc"},
+}
+
+// isMacro reports whether p is a package dependency macro
+// (uppercase name).
+func isMacro(p string) bool {
+	return 'A' <= p[0] && p[0] <= 'Z'
+}
+
+func allowed(pkg string) map[string]bool {
+	m := map[string]bool{}
+	var allow func(string)
+	allow = func(p string) {
+		if m[p] {
+			return
+		}
+		m[p] = true // set even for macros, to avoid loop on cycle
+
+		// Upper-case names are macro-expanded.
+		if isMacro(p) {
+			for _, pp := range pkgDeps[p] {
+				allow(pp)
+			}
+		}
+	}
+	for _, pp := range pkgDeps[pkg] {
+		allow(pp)
+	}
+	return m
+}
+
+var bools = []bool{false, true}
+var geese = []string{"darwin", "freebsd", "linux", "netbsd", "openbsd", "plan9", "windows"}
+var goarches = []string{"386", "amd64", "arm"}
+
+type osPkg struct {
+	goos, pkg string
+}
+
+// allowedErrors are the operating systems and packages known to contain errors
+// (currently just "no Go source files")
+var allowedErrors = map[osPkg]bool{
+	osPkg{"windows", "log/syslog"}: true,
+	osPkg{"plan9", "log/syslog"}:   true,
+}
+
+func TestDependencies(t *testing.T) {
+	var all []string
+
+	for k := range pkgDeps {
+		all = append(all, k)
+	}
+	sort.Strings(all)
+
+	ctxt := build.Default
+	test := func(mustImport bool) {
+		for _, pkg := range all {
+			if isMacro(pkg) {
+				continue
+			}
+			p, err := ctxt.Import(pkg, "", 0)
+			if err != nil {
+				if allowedErrors[osPkg{ctxt.GOOS, pkg}] {
+					continue
+				}
+				// Some of the combinations we try might not
+				// be reasonable (like arm,plan9,cgo), so ignore
+				// errors for the auto-generated combinations.
+				if !mustImport {
+					continue
+				}
+				t.Errorf("%s/%s/cgo=%v %v", ctxt.GOOS, ctxt.GOARCH, ctxt.CgoEnabled, err)
+				continue
+			}
+			ok := allowed(pkg)
+			var bad []string
+			for _, imp := range p.Imports {
+				if !ok[imp] {
+					bad = append(bad, imp)
+				}
+			}
+			if bad != nil {
+				t.Errorf("%s/%s/cgo=%v unexpected dependency: %s imports %v", ctxt.GOOS, ctxt.GOARCH, ctxt.CgoEnabled, pkg, bad)
+			}
+		}
+	}
+	test(true)
+
+	if testing.Short() {
+		t.Logf("skipping other systems")
+		return
+	}
+
+	for _, ctxt.GOOS = range geese {
+		for _, ctxt.GOARCH = range goarches {
+			for _, ctxt.CgoEnabled = range bools {
+				test(false)
+			}
+		}
+	}
+}
diff --git a/src/pkg/go/build/syslist.go b/src/pkg/go/build/syslist.go
index 8a2db8fa3..ea21f3c74 100644
--- a/src/pkg/go/build/syslist.go
+++ b/src/pkg/go/build/syslist.go
@@ -1,4 +1,6 @@
-// Generated automatically by make.
+// Copyright 2011 The Go Authors.  All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
 
 package build
 
diff --git a/src/pkg/go/parser/error_test.go b/src/pkg/go/parser/error_test.go
new file mode 100644
index 000000000..377c8b80c
--- /dev/null
+++ b/src/pkg/go/parser/error_test.go
@@ -0,0 +1,166 @@
+// Copyright 2012 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+// This file implements a parser test harness. The files in the testdata
+// directory are parsed and the errors reported are compared against the
+// error messages expected in the test files. The test files must end in
+// .src rather than .go so that they are not disturbed by gofmt runs.
+//
+// Expected errors are indicated in the test files by putting a comment
+// of the form /* ERROR "rx" */ immediately following an offending token.
+// The harness will verify that an error matching the regular expression
+// rx is reported at that source position.
+//
+// For instance, the following test file indicates that a "not declared"
+// error should be reported for the undeclared variable x:
+//
+//	package p
+//	func f() {
+//		_ = x /* ERROR "not declared" */ + 1
+//	}
+
+package parser
+
+import (
+	"go/scanner"
+	"go/token"
+	"io/ioutil"
+	"path/filepath"
+	"regexp"
+	"strings"
+	"testing"
+)
+
+const testdata = "testdata"
+
+// getFile assumes that each filename occurs at most once
+func getFile(filename string) (file *token.File) {
+	fset.Iterate(func(f *token.File) bool {
+		if f.Name() == filename {
+			if file != nil {
+				panic(filename + " used multiple times")
+			}
+			file = f
+		}
+		return true
+	})
+	return file
+}
+
+func getPos(filename string, offset int) token.Pos {
+	if f := getFile(filename); f != nil {
+		return f.Pos(offset)
+	}
+	return token.NoPos
+}
+
+// ERROR comments must be of the form /* ERROR "rx" */ and rx is
+// a regular expression that matches the expected error message.
+//
+var errRx = regexp.MustCompile(`^/\* *ERROR *"([^"]*)" *\*/$`)
+
+// expectedErrors collects the regular expressions of ERROR comments found
+// in files and returns them as a map of error positions to error messages.
+//
+func expectedErrors(t *testing.T, filename string, src []byte) map[token.Pos]string {
+	errors := make(map[token.Pos]string)
+
+	var s scanner.Scanner
+	// file was parsed already - do not add it again to the file
+	// set otherwise the position information returned here will
+	// not match the position information collected by the parser
+	s.Init(getFile(filename), src, nil, scanner.ScanComments)
+	var prev token.Pos // position of last non-comment, non-semicolon token
+
+	for {
+		pos, tok, lit := s.Scan()
+		switch tok {
+		case token.EOF:
+			return errors
+		case token.COMMENT:
+			s := errRx.FindStringSubmatch(lit)
+			if len(s) == 2 {
+				errors[prev] = string(s[1])
+			}
+		default:
+			prev = pos
+		}
+	}
+
+	panic("unreachable")
+}
+
+// compareErrors compares the map of expected error messages with the list
+// of found errors and reports discrepancies.
+//
+func compareErrors(t *testing.T, expected map[token.Pos]string, found scanner.ErrorList) {
+	for _, error := range found {
+		// error.Pos is a token.Position, but we want
+		// a token.Pos so we can do a map lookup
+		pos := getPos(error.Pos.Filename, error.Pos.Offset)
+		if msg, found := expected[pos]; found {
+			// we expect a message at pos; check if it matches
+			rx, err := regexp.Compile(msg)
+			if err != nil {
+				t.Errorf("%s: %v", error.Pos, err)
+				continue
+			}
+			if match := rx.MatchString(error.Msg); !match {
+				t.Errorf("%s: %q does not match %q", error.Pos, error.Msg, msg)
+				continue
+			}
+			// we have a match - eliminate this error
+			delete(expected, pos)
+		} else {
+			// To keep in mind when analyzing failed test output:
+			// If the same error position occurs multiple times in errors,
+			// this message will be triggered (because the first error at
+			// the position removes this position from the expected errors).
+			t.Errorf("%s: unexpected error: %s", error.Pos, error.Msg)
+		}
+	}
+
+	// there should be no expected errors left
+	if len(expected) > 0 {
+		t.Errorf("%d errors not reported:", len(expected))
+		for pos, msg := range expected {
+			t.Errorf("%s: %s\n", fset.Position(pos), msg)
+		}
+	}
+}
+
+func checkErrors(t *testing.T, filename string, input interface{}) {
+	src, err := readSource(filename, input)
+	if err != nil {
+		t.Error(err)
+		return
+	}
+
+	_, err = ParseFile(fset, filename, src, DeclarationErrors)
+	found, ok := err.(scanner.ErrorList)
+	if err != nil && !ok {
+		t.Error(err)
+		return
+	}
+
+	// we are expecting the following errors
+	// (collect these after parsing a file so that it is found in the file set)
+	expected := expectedErrors(t, filename, src)
+
+	// verify errors returned by the parser
+	compareErrors(t, expected, found)
+}
+
+func TestErrors(t *testing.T) {
+	list, err := ioutil.ReadDir(testdata)
+	if err != nil {
+		t.Fatal(err)
+	}
+	for _, fi := range list {
+		name := fi.Name()
+		if !fi.IsDir() && !strings.HasPrefix(name, ".") && strings.HasSuffix(name, ".src") {
+			checkErrors(t, filepath.Join(testdata, name), nil)
+		}
+	}
+}
diff --git a/src/pkg/go/parser/parser.go b/src/pkg/go/parser/parser.go
index a122baf08..e362e13a7 100644
--- a/src/pkg/go/parser/parser.go
+++ b/src/pkg/go/parser/parser.go
@@ -40,6 +40,13 @@ type parser struct {
 	tok token.Token // one token look-ahead
 	lit string      // token literal
 
+	// Error recovery
+	// (used to limit the number of calls to syncXXX functions
+	// w/o making scanning progress - avoids potential endless
+	// loops across multiple parser functions during error recovery)
+	syncPos token.Pos // last synchronization position
+	syncCnt int       // number of calls to syncXXX without progress
+
 	// Non-syntactic parser control
 	exprLev int // < 0: in control clause, >= 0: in expression
 
@@ -362,18 +369,36 @@ func (p *parser) expect(tok token.Token) token.Pos {
 // expectClosing is like expect but provides a better error message
 // for the common case of a missing comma before a newline.
 //
-func (p *parser) expectClosing(tok token.Token, construct string) token.Pos {
+func (p *parser) expectClosing(tok token.Token, context string) token.Pos {
 	if p.tok != tok && p.tok == token.SEMICOLON && p.lit == "\n" {
-		p.error(p.pos, "missing ',' before newline in "+construct)
+		p.error(p.pos, "missing ',' before newline in "+context)
 		p.next()
 	}
 	return p.expect(tok)
 }
 
 func (p *parser) expectSemi() {
+	// semicolon is optional before a closing ')' or '}'
 	if p.tok != token.RPAREN && p.tok != token.RBRACE {
-		p.expect(token.SEMICOLON)
+		if p.tok == token.SEMICOLON {
+			p.next()
+		} else {
+			p.errorExpected(p.pos, "';'")
+			syncStmt(p)
+		}
+	}
+}
+
+func (p *parser) atComma(context string) bool {
+	if p.tok == token.COMMA {
+		return true
+	}
+	if p.tok == token.SEMICOLON && p.lit == "\n" {
+		p.error(p.pos, "missing ',' before newline in "+context)
+		return true // "insert" the comma and continue
+
 	}
+	return false
 }
 
 func assert(cond bool, msg string) {
@@ -382,6 +407,68 @@ func assert(cond bool, msg string) {
 	}
 }
 
+// syncStmt advances to the next statement.
+// Used for synchronization after an error.
+//
+func syncStmt(p *parser) {
+	for {
+		switch p.tok {
+		case token.BREAK, token.CONST, token.CONTINUE, token.DEFER,
+			token.FALLTHROUGH, token.FOR, token.GO, token.GOTO,
+			token.IF, token.RETURN, token.SELECT, token.SWITCH,
+			token.TYPE, token.VAR:
+			// Return only if parser made some progress since last
+			// sync or if it has not reached 10 sync calls without
+			// progress. Otherwise consume at least one token to
+			// avoid an endless parser loop (it is possible that
+			// both parseOperand and parseStmt call syncStmt and
+			// correctly do not advance, thus the need for the
+			// invocation limit p.syncCnt).
+			if p.pos == p.syncPos && p.syncCnt < 10 {
+				p.syncCnt++
+				return
+			}
+			if p.pos > p.syncPos {
+				p.syncPos = p.pos
+				p.syncCnt = 0
+				return
+			}
+			// Reaching here indicates a parser bug, likely an
+			// incorrect token list in this function, but it only
+			// leads to skipping of possibly correct code if a
+			// previous error is present, and thus is preferred
+			// over a non-terminating parse.
+		case token.EOF:
+			return
+		}
+		p.next()
+	}
+}
+
+// syncDecl advances to the next declaration.
+// Used for synchronization after an error.
+//
+func syncDecl(p *parser) {
+	for {
+		switch p.tok {
+		case token.CONST, token.TYPE, token.VAR:
+			// see comments in syncStmt
+			if p.pos == p.syncPos && p.syncCnt < 10 {
+				p.syncCnt++
+				return
+			}
+			if p.pos > p.syncPos {
+				p.syncPos = p.pos
+				p.syncCnt = 0
+				return
+			}
+		case token.EOF:
+			return
+		}
+		p.next()
+	}
+}
+
 // ----------------------------------------------------------------------------
 // Identifiers
 
@@ -522,9 +609,11 @@ func (p *parser) makeIdentList(list []ast.Expr) []*ast.Ident {
 	for i, x := range list {
 		ident, isIdent := x.(*ast.Ident)
 		if !isIdent {
-			pos := x.Pos()
-			p.errorExpected(pos, "identifier")
-			ident = &ast.Ident{NamePos: pos, Name: "_"}
+			if _, isBad := x.(*ast.BadExpr); !isBad {
+				// only report error if it's a new one
+				p.errorExpected(x.Pos(), "identifier")
+			}
+			ident = &ast.Ident{NamePos: x.Pos(), Name: "_"}
 		}
 		idents[i] = ident
 	}
@@ -688,7 +777,7 @@ func (p *parser) parseParameterList(scope *ast.Scope, ellipsisOk bool) (params [
 			// Go spec: The scope of an identifier denoting a function
 			// parameter or result variable is the function body.
 			p.declare(field, nil, scope, ast.Var, idents...)
-			if p.tok != token.COMMA {
+			if !p.atComma("parameter list") {
 				break
 			}
 			p.next()
@@ -991,19 +1080,19 @@ func (p *parser) parseOperand(lhs bool) ast.Expr {
 
 	case token.FUNC:
 		return p.parseFuncTypeOrLit()
+	}
 
-	default:
-		if typ := p.tryIdentOrType(true); typ != nil {
-			// could be type for composite literal or conversion
-			_, isIdent := typ.(*ast.Ident)
-			assert(!isIdent, "type cannot be identifier")
-			return typ
-		}
+	if typ := p.tryIdentOrType(true); typ != nil {
+		// could be type for composite literal or conversion
+		_, isIdent := typ.(*ast.Ident)
+		assert(!isIdent, "type cannot be identifier")
+		return typ
 	}
 
+	// we have an error
 	pos := p.pos
 	p.errorExpected(pos, "operand")
-	p.next() // make progress
+	syncStmt(p)
 	return &ast.BadExpr{From: pos, To: p.pos}
 }
 
@@ -1078,7 +1167,7 @@ func (p *parser) parseCallOrConversion(fun ast.Expr) *ast.CallExpr {
 			ellipsis = p.pos
 			p.next()
 		}
-		if p.tok != token.COMMA {
+		if !p.atComma("argument list") {
 			break
 		}
 		p.next()
@@ -1118,7 +1207,7 @@ func (p *parser) parseElementList() (list []ast.Expr) {
 
 	for p.tok != token.RBRACE && p.tok != token.EOF {
 		list = append(list, p.parseElement(true))
-		if p.tok != token.COMMA {
+		if !p.atComma("composite literal") {
 			break
 		}
 		p.next()
@@ -1262,8 +1351,8 @@ L:
 				x = p.parseTypeAssertion(p.checkExpr(x))
 			default:
 				pos := p.pos
-				p.next() // make progress
 				p.errorExpected(pos, "selector or type assertion")
+				p.next() // make progress
 				x = &ast.BadExpr{From: pos, To: p.pos}
 			}
 		case token.LBRACK:
@@ -1471,7 +1560,10 @@ func (p *parser) parseCallExpr() *ast.CallExpr {
 	if call, isCall := x.(*ast.CallExpr); isCall {
 		return call
 	}
-	p.errorExpected(x.Pos(), "function/method call")
+	if _, isBad := x.(*ast.BadExpr); !isBad {
+		// only report error if it's a new one
+		p.errorExpected(x.Pos(), "function/method call")
+	}
 	return nil
 }
 
@@ -1862,7 +1954,7 @@ func (p *parser) parseStmt() (s ast.Stmt) {
 
 	switch p.tok {
 	case token.CONST, token.TYPE, token.VAR:
-		s = &ast.DeclStmt{Decl: p.parseDecl()}
+		s = &ast.DeclStmt{Decl: p.parseDecl(syncStmt)}
 	case
 		// tokens that may start an expression
 		token.IDENT, token.INT, token.FLOAT, token.IMAG, token.CHAR, token.STRING, token.FUNC, token.LPAREN, // operands
@@ -1904,7 +1996,7 @@ func (p *parser) parseStmt() (s ast.Stmt) {
 		// no statement found
 		pos := p.pos
 		p.errorExpected(pos, "statement")
-		p.next() // make progress
+		syncStmt(p)
 		s = &ast.BadStmt{From: pos, To: p.pos}
 	}
 
@@ -2095,8 +2187,13 @@ func (p *parser) parseReceiver(scope *ast.Scope) *ast.FieldList {
 	recv := par.List[0]
 	base := deref(recv.Type)
 	if _, isIdent := base.(*ast.Ident); !isIdent {
-		p.errorExpected(base.Pos(), "(unqualified) identifier")
-		par.List = []*ast.Field{{Type: &ast.BadExpr{From: recv.Pos(), To: recv.End()}}}
+		if _, isBad := base.(*ast.BadExpr); !isBad {
+			// only report error if it's a new one
+			p.errorExpected(base.Pos(), "(unqualified) identifier")
+		}
+		par.List = []*ast.Field{
+			{Type: &ast.BadExpr{From: recv.Pos(), To: recv.End()}},
+		}
 	}
 
 	return par
@@ -2152,7 +2249,7 @@ func (p *parser) parseFuncDecl() *ast.FuncDecl {
 	return decl
 }
 
-func (p *parser) parseDecl() ast.Decl {
+func (p *parser) parseDecl(sync func(*parser)) ast.Decl {
 	if p.trace {
 		defer un(trace(p, "Declaration"))
 	}
@@ -2174,9 +2271,8 @@ func (p *parser) parseDecl() ast.Decl {
 	default:
 		pos := p.pos
 		p.errorExpected(pos, "declaration")
-		p.next() // make progress
-		decl := &ast.BadDecl{From: pos, To: p.pos}
-		return decl
+		sync(p)
+		return &ast.BadDecl{From: pos, To: p.pos}
 	}
 
 	return p.parseGenDecl(p.tok, f)
@@ -2215,7 +2311,7 @@ func (p *parser) parseFile() *ast.File {
 		if p.mode&ImportsOnly == 0 {
 			// rest of package body
 			for p.tok != token.EOF {
-				decls = append(decls, p.parseDecl())
+				decls = append(decls, p.parseDecl(syncDecl))
 			}
 		}
 	}
diff --git a/src/pkg/go/parser/parser_test.go b/src/pkg/go/parser/parser_test.go
index 93ca3d6aa..5e45acd00 100644
--- a/src/pkg/go/parser/parser_test.go
+++ b/src/pkg/go/parser/parser_test.go
@@ -14,87 +14,14 @@ import (
 
 var fset = token.NewFileSet()
 
-var illegalInputs = []interface{}{
-	nil,
-	3.14,
-	[]byte(nil),
-	"foo!",
-	`package p; func f() { if /* should have condition */ {} };`,
-	`package p; func f() { if ; /* should have condition */ {} };`,
-	`package p; func f() { if f(); /* should have condition */ {} };`,
-	`package p; const c; /* should have constant value */`,
-	`package p; func f() { if _ = range x; true {} };`,
-	`package p; func f() { switch _ = range x; true {} };`,
-	`package p; func f() { for _ = range x ; ; {} };`,
-	`package p; func f() { for ; ; _ = range x {} };`,
-	`package p; func f() { for ; _ = range x ; {} };`,
-	`package p; func f() { switch t = t.(type) {} };`,
-	`package p; func f() { switch t, t = t.(type) {} };`,
-	`package p; func f() { switch t = t.(type), t {} };`,
-	`package p; var a = [1]int; /* illegal expression */`,
-	`package p; var a = [...]int; /* illegal expression */`,
-	`package p; var a = struct{} /* illegal expression */`,
-	`package p; var a = func(); /* illegal expression */`,
-	`package p; var a = interface{} /* illegal expression */`,
-	`package p; var a = []int /* illegal expression */`,
-	`package p; var a = map[int]int /* illegal expression */`,
-	`package p; var a = chan int; /* illegal expression */`,
-	`package p; var a = []int{[]int}; /* illegal expression */`,
-	`package p; var a = ([]int); /* illegal expression */`,
-	`package p; var a = a[[]int:[]int]; /* illegal expression */`,
-	`package p; var a = <- chan int; /* illegal expression */`,
-	`package p; func f() { select { case _ <- chan int: } };`,
-}
-
-func TestParseIllegalInputs(t *testing.T) {
-	for _, src := range illegalInputs {
-		_, err := ParseFile(fset, "", src, 0)
-		if err == nil {
-			t.Errorf("ParseFile(%v) should have failed", src)
-		}
-	}
-}
-
-var validPrograms = []string{
-	"package p\n",
-	`package p;`,
-	`package p; import "fmt"; func f() { fmt.Println("Hello, World!") };`,
-	`package p; func f() { if f(T{}) {} };`,
-	`package p; func f() { _ = (<-chan int)(x) };`,
-	`package p; func f() { _ = (<-chan <-chan int)(x) };`,
-	`package p; func f(func() func() func());`,
-	`package p; func f(...T);`,
-	`package p; func f(float, ...int);`,
-	`package p; func f(x int, a ...int) { f(0, a...); f(1, a...,) };`,
-	`package p; func f(int,) {};`,
-	`package p; func f(...int,) {};`,
-	`package p; func f(x ...int,) {};`,
-	`package p; type T []int; var a []bool; func f() { if a[T{42}[0]] {} };`,
-	`package p; type T []int; func g(int) bool { return true }; func f() { if g(T{42}[0]) {} };`,
-	`package p; type T []int; func f() { for _ = range []int{T{42}[0]} {} };`,
-	`package p; var a = T{{1, 2}, {3, 4}}`,
-	`package p; func f() { select { case <- c: case c <- d: case c <- <- d: case <-c <- d: } };`,
-	`package p; func f() { select { case x := (<-c): } };`,
-	`package p; func f() { if ; true {} };`,
-	`package p; func f() { switch ; {} };`,
-	`package p; func f() { for _ = range "foo" + "bar" {} };`,
-}
-
-func TestParseValidPrograms(t *testing.T) {
-	for _, src := range validPrograms {
-		_, err := ParseFile(fset, "", src, SpuriousErrors)
-		if err != nil {
-			t.Errorf("ParseFile(%q): %v", src, err)
-		}
-	}
-}
-
 var validFiles = []string{
 	"parser.go",
 	"parser_test.go",
+	"error_test.go",
+	"short_test.go",
 }
 
-func TestParse3(t *testing.T) {
+func TestParse(t *testing.T) {
 	for _, filename := range validFiles {
 		_, err := ParseFile(fset, filename, nil, DeclarationErrors)
 		if err != nil {
@@ -116,7 +43,7 @@ func nameFilter(filename string) bool {
 
 func dirFilter(f os.FileInfo) bool { return nameFilter(f.Name()) }
 
-func TestParse4(t *testing.T) {
+func TestParseDir(t *testing.T) {
 	path := "."
 	pkgs, err := ParseDir(fset, path, dirFilter, 0)
 	if err != nil {
@@ -158,7 +85,7 @@ func TestParseExpr(t *testing.T) {
 	}
 
 	// it must not crash
-	for _, src := range validPrograms {
+	for _, src := range valids {
 		ParseExpr(src)
 	}
 }
diff --git a/src/pkg/go/parser/short_test.go b/src/pkg/go/parser/short_test.go
new file mode 100644
index 000000000..238492bf3
--- /dev/null
+++ b/src/pkg/go/parser/short_test.go
@@ -0,0 +1,75 @@
+// Copyright 2009 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+// This file contains test cases for short valid and invalid programs.
+
+package parser
+
+import "testing"
+
+var valids = []string{
+	"package p\n",
+	`package p;`,
+	`package p; import "fmt"; func f() { fmt.Println("Hello, World!") };`,
+	`package p; func f() { if f(T{}) {} };`,
+	`package p; func f() { _ = (<-chan int)(x) };`,
+	`package p; func f() { _ = (<-chan <-chan int)(x) };`,
+	`package p; func f(func() func() func());`,
+	`package p; func f(...T);`,
+	`package p; func f(float, ...int);`,
+	`package p; func f(x int, a ...int) { f(0, a...); f(1, a...,) };`,
+	`package p; func f(int,) {};`,
+	`package p; func f(...int,) {};`,
+	`package p; func f(x ...int,) {};`,
+	`package p; type T []int; var a []bool; func f() { if a[T{42}[0]] {} };`,
+	`package p; type T []int; func g(int) bool { return true }; func f() { if g(T{42}[0]) {} };`,
+	`package p; type T []int; func f() { for _ = range []int{T{42}[0]} {} };`,
+	`package p; var a = T{{1, 2}, {3, 4}}`,
+	`package p; func f() { select { case <- c: case c <- d: case c <- <- d: case <-c <- d: } };`,
+	`package p; func f() { select { case x := (<-c): } };`,
+	`package p; func f() { if ; true {} };`,
+	`package p; func f() { switch ; {} };`,
+	`package p; func f() { for _ = range "foo" + "bar" {} };`,
+}
+
+func TestValid(t *testing.T) {
+	for _, src := range valids {
+		checkErrors(t, src, src)
+	}
+}
+
+var invalids = []string{
+	`foo /* ERROR "expected 'package'" */ !`,
+	`package p; func f() { if { /* ERROR "expected operand" */ } };`,
+	`package p; func f() { if ; { /* ERROR "expected operand" */ } };`,
+	`package p; func f() { if f(); { /* ERROR "expected operand" */ } };`,
+	`package p; const c; /* ERROR "expected '='" */`,
+	`package p; func f() { if _ /* ERROR "expected condition" */ = range x; true {} };`,
+	`package p; func f() { switch _ /* ERROR "expected condition" */ = range x; true {} };`,
+	`package p; func f() { for _ = range x ; /* ERROR "expected '{'" */ ; {} };`,
+	`package p; func f() { for ; ; _ = range /* ERROR "expected operand" */ x {} };`,
+	`package p; func f() { for ; _ /* ERROR "expected condition" */ = range x ; {} };`,
+	`package p; func f() { switch t /* ERROR "expected condition" */ = t.(type) {} };`,
+	`package p; func f() { switch t /* ERROR "expected condition" */ , t = t.(type) {} };`,
+	`package p; func f() { switch t /* ERROR "expected condition" */ = t.(type), t {} };`,
+	`package p; var a = [ /* ERROR "expected expression" */ 1]int;`,
+	`package p; var a = [ /* ERROR "expected expression" */ ...]int;`,
+	`package p; var a = struct /* ERROR "expected expression" */ {}`,
+	`package p; var a = func /* ERROR "expected expression" */ ();`,
+	`package p; var a = interface /* ERROR "expected expression" */ {}`,
+	`package p; var a = [ /* ERROR "expected expression" */ ]int`,
+	`package p; var a = map /* ERROR "expected expression" */ [int]int`,
+	`package p; var a = chan /* ERROR "expected expression" */ int;`,
+	`package p; var a = []int{[ /* ERROR "expected expression" */ ]int};`,
+	`package p; var a = ( /* ERROR "expected expression" */ []int);`,
+	`package p; var a = a[[ /* ERROR "expected expression" */ ]int:[]int];`,
+	`package p; var a = <-  /* ERROR "expected expression" */ chan int;`,
+	`package p; func f() { select { case _ <- chan  /* ERROR "expected expression" */ int: } };`,
+}
+
+func TestInvalid(t *testing.T) {
+	for _, src := range invalids {
+		checkErrors(t, src, src)
+	}
+}
diff --git a/src/pkg/go/parser/testdata/commas.src b/src/pkg/go/parser/testdata/commas.src
new file mode 100644
index 000000000..af6e70645
--- /dev/null
+++ b/src/pkg/go/parser/testdata/commas.src
@@ -0,0 +1,19 @@
+// Copyright 2012 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+// Test case for error messages/parser synchronization
+// after missing commas.
+
+package p
+
+var _ = []int{
+	0 /* ERROR "missing ','" */
+}
+
+var _ = []int{
+	0,
+	1,
+	2,
+	3 /* ERROR "missing ','" */
+}
diff --git a/src/pkg/go/parser/testdata/issue3106.src b/src/pkg/go/parser/testdata/issue3106.src
new file mode 100644
index 000000000..82796c8ce
--- /dev/null
+++ b/src/pkg/go/parser/testdata/issue3106.src
@@ -0,0 +1,46 @@
+// Copyright 2012 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+// Test case for issue 3106: Better synchronization of
+// parser after certain syntax errors.
+
+package main
+
+func f() {
+	var m Mutex
+	c := MakeCond(&m)
+	percent := 0
+	const step = 10
+	for i := 0; i < 5; i++ {
+		go func() {
+			for {
+				// Emulates some useful work.
+				time.Sleep(1e8)
+				m.Lock()
+				defer
+				if /* ERROR "expected operand, found 'if'" */ percent == 100 {
+					m.Unlock()
+					break
+				}
+				percent++
+				if percent % step == 0 {
+					//c.Signal()
+				}
+				m.Unlock()
+			}
+		}()
+	}
+	for {
+		m.Lock()
+		if percent == 0 || percent % step != 0 {
+			c.Wait()
+		}
+		fmt.Print(",")
+		if percent == 100 {
+			m.Unlock()
+			break
+		}
+		m.Unlock()
+	}
+}
diff --git a/src/pkg/go/printer/example_test.go b/src/pkg/go/printer/example_test.go
new file mode 100644
index 000000000..e570040ba
--- /dev/null
+++ b/src/pkg/go/printer/example_test.go
@@ -0,0 +1,67 @@
+// Copyright 2012 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package printer_test
+
+import (
+	"bytes"
+	"fmt"
+	"go/ast"
+	"go/parser"
+	"go/printer"
+	"go/token"
+	"strings"
+	"testing"
+)
+
+// Dummy test function so that godoc does not use the entire file as example.
+func Test(*testing.T) {}
+
+func parseFunc(filename, functionname string) (fun *ast.FuncDecl, fset *token.FileSet) {
+	fset = token.NewFileSet()
+	if file, err := parser.ParseFile(fset, filename, nil, 0); err == nil {
+		for _, d := range file.Decls {
+			if f, ok := d.(*ast.FuncDecl); ok && f.Name.Name == functionname {
+				fun = f
+				return
+			}
+		}
+	}
+	panic("function not found")
+}
+
+func ExampleFprint() {
+	// Parse source file and extract the AST without comments for
+	// this function, with position information referring to the
+	// file set fset.
+	funcAST, fset := parseFunc("example_test.go", "ExampleFprint")
+
+	// Print the function body into buffer buf.
+	// The file set is provided to the printer so that it knows
+	// about the original source formatting and can add additional
+	// line breaks where they were present in the source.
+	var buf bytes.Buffer
+	printer.Fprint(&buf, fset, funcAST.Body)
+
+	// Remove braces {} enclosing the function body, unindent,
+	// and trim leading and trailing white space.
+	s := buf.String()
+	s = s[1 : len(s)-1]
+	s = strings.TrimSpace(strings.Replace(s, "\n\t", "\n", -1))
+
+	// Print the cleaned-up body text to stdout.
+	fmt.Println(s)
+
+	// output:
+	// funcAST, fset := parseFunc("example_test.go", "ExampleFprint")
+	//
+	// var buf bytes.Buffer
+	// printer.Fprint(&buf, fset, funcAST.Body)
+	//
+	// s := buf.String()
+	// s = s[1 : len(s)-1]
+	// s = strings.TrimSpace(strings.Replace(s, "\n\t", "\n", -1))
+	//
+	// fmt.Println(s)
+}
diff --git a/src/pkg/go/printer/nodes.go b/src/pkg/go/printer/nodes.go
index 05b4ef59a..727d2a371 100644
--- a/src/pkg/go/printer/nodes.go
+++ b/src/pkg/go/printer/nodes.go
@@ -15,7 +15,7 @@ import (
 	"unicode/utf8"
 )
 
-// Other formatting issues:
+// Formatting issues:
 // - better comment formatting for /*-style comments at the end of a line (e.g. a declaration)
 //   when the comment spans multiple lines; if such a comment is just two lines, formatting is
 //   not idempotent
@@ -365,7 +365,7 @@ func (p *printer) setLineComment(text string) {
 }
 
 func (p *printer) isMultiLine(n ast.Node) bool {
-	return p.lineFor(n.End())-p.lineFor(n.Pos()) > 1
+	return p.lineFor(n.End())-p.lineFor(n.Pos()) > 0
 }
 
 func (p *printer) fieldList(fields *ast.FieldList, isStruct, isIncomplete bool) {
@@ -964,6 +964,41 @@ func (p *printer) controlClause(isForStmt bool, init ast.Stmt, expr ast.Expr, po
 	}
 }
 
+// indentList reports whether an expression list would look better if it
+// were indented wholesale (starting with the very first element, rather
+// than starting at the first line break).
+//
+func (p *printer) indentList(list []ast.Expr) bool {
+	// Heuristic: indentList returns true if there are more than one multi-
+	// line element in the list, or if there is any element that is not
+	// starting on the same line as the previous one ends.
+	if len(list) >= 2 {
+		var b = p.lineFor(list[0].Pos())
+		var e = p.lineFor(list[len(list)-1].End())
+		if 0 < b && b < e {
+			// list spans multiple lines
+			n := 0 // multi-line element count
+			line := b
+			for _, x := range list {
+				xb := p.lineFor(x.Pos())
+				xe := p.lineFor(x.End())
+				if line < xb {
+					// x is not starting on the same
+					// line as the previous one ended
+					return true
+				}
+				if xb < xe {
+					// x is a multi-line element
+					n++
+				}
+				line = xe
+			}
+			return n > 1
+		}
+	}
+	return false
+}
+
 func (p *printer) stmt(stmt ast.Stmt, nextIsRBrace bool) {
 	p.print(stmt.Pos())
 
@@ -1030,7 +1065,18 @@ func (p *printer) stmt(stmt ast.Stmt, nextIsRBrace bool) {
 		p.print(token.RETURN)
 		if s.Results != nil {
 			p.print(blank)
-			p.exprList(s.Pos(), s.Results, 1, 0, token.NoPos)
+			// Use indentList heuristic to make corner cases look
+			// better (issue 1207). A more systematic approach would
+			// always indent, but this would cause significant
+			// reformatting of the code base and not necessarily
+			// lead to more nicely formatted code in general.
+			if p.indentList(s.Results) {
+				p.print(indent)
+				p.exprList(s.Pos(), s.Results, 1, noIndent, token.NoPos)
+				p.print(unindent)
+			} else {
+				p.exprList(s.Pos(), s.Results, 1, 0, token.NoPos)
+			}
 		}
 
 	case *ast.BranchStmt:
@@ -1200,9 +1246,9 @@ func keepTypeColumn(specs []ast.Spec) []bool {
 	return m
 }
 
-func (p *printer) valueSpec(s *ast.ValueSpec, keepType, doIndent bool) {
+func (p *printer) valueSpec(s *ast.ValueSpec, keepType bool) {
 	p.setComment(s.Doc)
-	p.identList(s.Names, doIndent) // always present
+	p.identList(s.Names, false) // always present
 	extraTabs := 3
 	if s.Type != nil || keepType {
 		p.print(vtab)
@@ -1290,7 +1336,7 @@ func (p *printer) genDecl(d *ast.GenDecl) {
 					if i > 0 {
 						p.linebreak(p.lineFor(s.Pos()), 1, ignore, newSection)
 					}
-					p.valueSpec(s.(*ast.ValueSpec), keepType[i], false)
+					p.valueSpec(s.(*ast.ValueSpec), keepType[i])
 					newSection = p.isMultiLine(s)
 				}
 			} else {
diff --git a/src/pkg/go/printer/testdata/declarations.golden b/src/pkg/go/printer/testdata/declarations.golden
index 7ed7cb61a..71ed32ed1 100644
--- a/src/pkg/go/printer/testdata/declarations.golden
+++ b/src/pkg/go/printer/testdata/declarations.golden
@@ -500,7 +500,7 @@ type _ struct {
 
 type _ struct {
 	a, b,
-	c, d		int	// this line should be indented
+	c, d	int	// this line should be indented
 	u, v, w, x	float	// this line should be indented
 	p, q,
 	r, s	float	// this line should be indented
@@ -562,10 +562,21 @@ var a2, b2,
 
 var (
 	a3, b3,
-	c3, d3		int	// this line should be indented
+	c3, d3	int	// this line should be indented
 	a4, b4, c4	int	// this line should be indented
 )
 
+// Test case from issue 3304: multi-line declarations must end
+// a formatting section and not influence indentation of the
+// next line.
+var (
+	minRefreshTimeSec	= flag.Int64("min_refresh_time_sec", 604800,
+		"minimum time window between two refreshes for a given user.")
+	x	= flag.Int64("refresh_user_rollout_percent", 100,
+		"temporary flag to ramp up the refresh user rpc")
+	aVeryLongVariableName	= stats.GetVarInt("refresh-user-count")
+)
+
 func _() {
 	var privateKey2 = &Block{Type:	"RSA PRIVATE KEY",
 		Headers:	map[string]string{},
diff --git a/src/pkg/go/printer/testdata/declarations.input b/src/pkg/go/printer/testdata/declarations.input
index df8c2b167..d74cff25d 100644
--- a/src/pkg/go/printer/testdata/declarations.input
+++ b/src/pkg/go/printer/testdata/declarations.input
@@ -577,6 +577,16 @@ c3, d3 int  // this line should be indented
 a4, b4, c4 int  // this line should be indented
 )
 
+// Test case from issue 3304: multi-line declarations must end
+// a formatting section and not influence indentation of the
+// next line.
+var (
+	minRefreshTimeSec = flag.Int64("min_refresh_time_sec", 604800,
+		"minimum time window between two refreshes for a given user.")
+	x = flag.Int64("refresh_user_rollout_percent", 100,
+		"temporary flag to ramp up the refresh user rpc")
+	aVeryLongVariableName = stats.GetVarInt("refresh-user-count")
+)
 
 func _() {
 	var privateKey2 = &Block{Type: "RSA PRIVATE KEY",
diff --git a/src/pkg/go/printer/testdata/statements.golden b/src/pkg/go/printer/testdata/statements.golden
index ffca21edb..4d70617bf 100644
--- a/src/pkg/go/printer/testdata/statements.golden
+++ b/src/pkg/go/printer/testdata/statements.golden
@@ -55,12 +55,24 @@ func _f() {
 	return T{
 		1,
 		2,
-	},
+	}, nil
+	return T{
+			1,
+			2,
+		},
+		T{
+			x:	3,
+			y:	4,
+		}, nil
+	return T{
+			1,
+			2,
+		},
 		nil
 	return T{
-		1,
-		2,
-	},
+			1,
+			2,
+		},
 		T{
 			x:	3,
 			y:	4,
@@ -70,10 +82,10 @@ func _f() {
 		z
 	return func() {}
 	return func() {
-		_ = 0
-	}, T{
-		1, 2,
-	}
+			_ = 0
+		}, T{
+			1, 2,
+		}
 	return func() {
 		_ = 0
 	}
@@ -84,6 +96,37 @@ func _f() {
 	}
 }
 
+// Formatting of multi-line returns: test cases from issue 1207.
+func F() (*T, os.Error) {
+	return &T{
+			X:	1,
+			Y:	2,
+		},
+		nil
+}
+
+func G() (*T, *T, os.Error) {
+	return &T{
+			X:	1,
+			Y:	2,
+		},
+		&T{
+			X:	3,
+			Y:	4,
+		},
+		nil
+}
+
+func _() interface{} {
+	return &fileStat{
+		name:		basename(file.name),
+		size:		mkSize(d.FileSizeHigh, d.FileSizeLow),
+		modTime:	mkModTime(d.LastWriteTime),
+		mode:		mkMode(d.FileAttributes),
+		sys:		mkSysFromFI(&d),
+	}, nil
+}
+
 // Formatting of if-statement headers.
 func _() {
 	if true {
diff --git a/src/pkg/go/printer/testdata/statements.input b/src/pkg/go/printer/testdata/statements.input
index 99945e955..bd03bc98b 100644
--- a/src/pkg/go/printer/testdata/statements.input
+++ b/src/pkg/go/printer/testdata/statements.input
@@ -55,6 +55,18 @@ func _f() {
 	return T{
 			1,
 			2,
+		}, nil
+	return T{
+			1,
+			2,
+		},
+		T{
+			x: 3,
+			y: 4,
+		}, nil
+	return T{
+			1,
+			2,
 		},
 		nil
 	return T{
@@ -84,6 +96,37 @@ func _f() {
 	}
 }
 
+// Formatting of multi-line returns: test cases from issue 1207.
+func F() (*T, os.Error) {
+       return &T{
+               X: 1,
+               Y: 2,
+       },
+               nil
+}
+
+func G() (*T, *T, os.Error) {
+       return &T{
+               X: 1,
+               Y: 2,
+       },
+               &T{
+                       X: 3,
+                       Y: 4,
+               },
+               nil
+}
+
+func _() interface{} {
+	return &fileStat{
+			name:    basename(file.name),
+			size:    mkSize(d.FileSizeHigh, d.FileSizeLow),
+			modTime: mkModTime(d.LastWriteTime),
+			mode:    mkMode(d.FileAttributes),
+			sys:     mkSysFromFI(&d),
+		}, nil
+}
+
 // Formatting of if-statement headers.
 func _() {
 	if true {}
diff --git a/src/pkg/go/scanner/scanner.go b/src/pkg/go/scanner/scanner.go
index 2395363b0..da508747a 100644
--- a/src/pkg/go/scanner/scanner.go
+++ b/src/pkg/go/scanner/scanner.go
@@ -109,7 +109,7 @@ const (
 func (s *Scanner) Init(file *token.File, src []byte, err ErrorHandler, mode Mode) {
 	// Explicitly initialize all fields since a scanner may be reused.
 	if file.Size() != len(src) {
-		panic("file size does not match src len")
+		panic(fmt.Sprintf("file size (%d) does not match src len (%d)", file.Size(), len(src)))
 	}
 	s.file = file
 	s.dir, _ = filepath.Split(file.Name())