libgo: update to Go1.13

    
    Reviewed-on: https://go-review.googlesource.com/c/gofrontend/+/194698

From-SVN: r275691

gcc/go/gofrontend/MERGE

-0950e905939f88c1421f8667ac4dc9e14528471c
+ceb1e4f5614b4772eed44f9cf57780e52f44753e
 
 The first line of this file holds the git revision number of the last
 merge done from the gofrontend repository.

libgo/MERGE

-60f14fddfee107dedd76c0be6b422a3d8ccc841a
+cc8838d645b2b7026c1f3aaceb011775c5ca3a08
 
 The first line of this file holds the git revision number of the
 last merge done from the master library sources.

libgo/Makefile.am

@@ -401,6 +401,7 @@ toolexeclibgounicode_DATA = \
 # Force them to be built.
 noinst_DATA = \
 	golang.org/x/net/nettest.gox \
+	internal/cfg.gox \
 	internal/testenv.gox \
 	internal/trace.gox \
 	net/internal/socktest.gox \

libgo/Makefile.in

@@ -856,10 +856,10 @@ toolexeclibgounicode_DATA = \
 # Some packages are only needed for tests, so unlike the other
 # internal packages nothing will explicitly depend on them.
 # Force them to be built.
-noinst_DATA = golang.org/x/net/nettest.gox internal/testenv.gox \
-	internal/trace.gox net/internal/socktest.gox \
-	os/signal/internal/pty.gox runtime/pprof/internal/profile.gox \
-	zdefaultcc.go
+noinst_DATA = golang.org/x/net/nettest.gox internal/cfg.gox \
+	internal/testenv.gox internal/trace.gox \
+	net/internal/socktest.gox os/signal/internal/pty.gox \
+	runtime/pprof/internal/profile.gox zdefaultcc.go
 @LIBGO_IS_RTEMS_FALSE@rtems_task_variable_add_file = 
 @LIBGO_IS_RTEMS_TRUE@rtems_task_variable_add_file = runtime/rtems-task-variable-add.c
 runtime_files = \

libgo/VERSION

-go1.13beta1
+go1.13

libgo/check-packages.txt

@@ -106,7 +106,6 @@ image/png
 index/suffixarray
 internal/cpu
 internal/fmtsort
-internal/oserror
 internal/poll
 internal/reflectlite
 internal/singleflight

libgo/go/cmd/cgo/gcc.go

@@ -811,10 +811,10 @@ func (p *Package) rewriteCall(f *File, call *Call) (string, bool) {
 	params := name.FuncType.Params
 	args := call.Call.Args
 
-	// Avoid a crash if the number of arguments is
-	// less than the number of parameters.
+	// Avoid a crash if the number of arguments doesn't match
+	// the number of parameters.
 	// This will be caught when the generated file is compiled.
-	if len(args) < len(params) {
+	if len(args) != len(params) {
 		return "", false
 	}
 
@@ -1257,6 +1257,8 @@ func (p *Package) isType(t ast.Expr) bool {
 		if strings.HasPrefix(t.Name, "_Ctype_") {
 			return true
 		}
+	case *ast.ParenExpr:
+		return p.isType(t.X)
 	case *ast.StarExpr:
 		return p.isType(t.X)
 	case *ast.ArrayType, *ast.StructType, *ast.FuncType, *ast.InterfaceType,

libgo/go/cmd/cgo/out.go

@@ -273,6 +273,35 @@ func (p *Package) writeDefs() {
 	}
 }
 
+// elfImportedSymbols is like elf.File.ImportedSymbols, but it
+// includes weak symbols.
+//
+// A bug in some versions of LLD (at least LLD 8) cause it to emit
+// several pthreads symbols as weak, but we need to import those. See
+// issue #31912 or https://bugs.llvm.org/show_bug.cgi?id=42442.
+//
+// When doing external linking, we hand everything off to the external
+// linker, which will create its own dynamic symbol tables. For
+// internal linking, this may turn weak imports into strong imports,
+// which could cause dynamic linking to fail if a symbol really isn't
+// defined. However, the standard library depends on everything it
+// imports, and this is the primary use of dynamic symbol tables with
+// internal linking.
+func elfImportedSymbols(f *elf.File) []elf.ImportedSymbol {
+	syms, _ := f.DynamicSymbols()
+	var imports []elf.ImportedSymbol
+	for _, s := range syms {
+		if (elf.ST_BIND(s.Info) == elf.STB_GLOBAL || elf.ST_BIND(s.Info) == elf.STB_WEAK) && s.Section == elf.SHN_UNDEF {
+			imports = append(imports, elf.ImportedSymbol{
+				Name:    s.Name,
+				Library: s.Library,
+				Version: s.Version,
+			})
+		}
+	}
+	return imports
+}
+
 func dynimport(obj string) {
 	stdout := os.Stdout
 	if *dynout != "" {
@@ -295,7 +324,7 @@ func dynimport(obj string) {
 				}
 			}
 		}
-		sym, _ := f.ImportedSymbols()
+		sym := elfImportedSymbols(f)
 		for _, s := range sym {
 			targ := s.Name
 			if s.Version != "" {

libgo/go/cmd/go/alldocs.go

@@ -78,6 +78,8 @@
 // If the arguments to build are a list of .go files from a single directory,
 // build treats them as a list of source files specifying a single package.
 //
+// When compiling packages, build ignores files that end in '_test.go'.
+//
 // When compiling a single main package, build writes
 // the resulting executable to an output file named after
 // the first source file ('go build ed.go rx.go' writes 'ed' or 'ed.exe')
@@ -88,8 +90,6 @@
 // build compiles the packages but discards the resulting object,
 // serving only as a check that the packages can be built.
 //
-// When compiling packages, build ignores files that end in '_test.go'.
-//
 // The -o flag forces build to write the resulting executable or object
 // to the named output file or directory, instead of the default behavior described
 // in the last two paragraphs. If the named output is a directory that exists,
@@ -566,17 +566,27 @@
 // The first step is to resolve which dependencies to add.
 //
 // For each named package or package pattern, get must decide which version of
-// the corresponding module to use. By default, get chooses the latest tagged
+// the corresponding module to use. By default, get looks up the latest tagged
 // release version, such as v0.4.5 or v1.2.3. If there are no tagged release
-// versions, get chooses the latest tagged pre-release version, such as
-// v0.0.1-pre1. If there are no tagged versions at all, get chooses the latest
-// known commit.
+// versions, get looks up the latest tagged pre-release version, such as
+// v0.0.1-pre1. If there are no tagged versions at all, get looks up the latest
+// known commit. If the module is not already required at a later version
+// (for example, a pre-release newer than the latest release), get will use
+// the version it looked up. Otherwise, get will use the currently
+// required version.
 //
 // This default version selection can be overridden by adding an @version
 // suffix to the package argument, as in 'go get golang.org/x/text@v0.3.0'.
+// The version may be a prefix: @v1 denotes the latest available version starting
+// with v1. See 'go help modules' under the heading 'Module queries' for the
+// full query syntax.
+//
 // For modules stored in source control repositories, the version suffix can
 // also be a commit hash, branch identifier, or other syntax known to the
-// source control system, as in 'go get golang.org/x/text@master'.
+// source control system, as in 'go get golang.org/x/text@master'. Note that
+// branches with names that overlap with other module query syntax cannot be
+// selected explicitly. For example, the suffix @v2 means the latest version
+// starting with v2, not the branch named v2.
 //
 // If a module under consideration is already a dependency of the current
 // development module, then get will update the required version.
@@ -586,12 +596,14 @@
 // depending on it as needed.
 //
 // The version suffix @latest explicitly requests the latest minor release of the
-// given path. The suffix @patch requests the latest patch release: if the path
-// is already in the build list, the selected version will have the same minor
-// version. If the path is not already in the build list, @patch is equivalent
-// to @latest. Neither @latest nor @patch will cause 'go get' to downgrade a module
-// in the build list if it is required at a newer pre-release version that is
-// newer than the latest released version.
+// module named by the given path. The suffix @upgrade is like @latest but
+// will not downgrade a module if it is already required at a revision or
+// pre-release version newer than the latest released version. The suffix
+// @patch requests the latest patch release: the latest released version
+// with the same major and minor version numbers as the currently required
+// version. Like @upgrade, @patch will not downgrade a module already required
+// at a newer version. If the path is not already required, @upgrade and @patch
+// are equivalent to @latest.
 //
 // Although get defaults to using the latest version of the module containing
 // a named package, it does not use the latest version of that module's
@@ -1006,6 +1018,7 @@
 //         Dir      string // absolute path to cached source root directory
 //         Sum      string // checksum for path, version (as in go.sum)
 //         GoModSum string // checksum for go.mod (as in go.sum)
+//         Latest   bool   // would @latest resolve to this version?
 //     }
 //
 // See 'go help modules' for more about module queries.
@@ -1562,6 +1575,9 @@
 // 	GOCACHE
 // 		The directory where the go command will store cached
 // 		information for reuse in future builds.
+// 	GODEBUG
+// 		Enable various debugging facilities. See 'go doc runtime'
+// 		for details.
 // 	GOENV
 // 		The location of the Go environment configuration file.
 // 		Cannot be set using 'go env -w'.
@@ -2496,12 +2512,25 @@
 // The string "latest" matches the latest available tagged version,
 // or else the underlying source repository's latest untagged revision.
 //
-// A revision identifier for the underlying source repository,
-// such as a commit hash prefix, revision tag, or branch name,
-// selects that specific code revision. If the revision is
-// also tagged with a semantic version, the query evaluates to
-// that semantic version. Otherwise the query evaluates to a
-// pseudo-version for the commit.
+// The string "upgrade" is like "latest", but if the module is
+// currently required at a later version than the version "latest"
+// would select (for example, a newer pre-release version), "upgrade"
+// will select the later version instead.
+//
+// The string "patch" matches the latest available tagged version
+// of a module with the same major and minor version numbers as the
+// currently required version. If no version is currently required,
+// "patch" is equivalent to "latest".
+//
+// A revision identifier for the underlying source repository, such as
+// a commit hash prefix, revision tag, or branch name, selects that
+// specific code revision. If the revision is also tagged with a
+// semantic version, the query evaluates to that semantic version.
+// Otherwise the query evaluates to a pseudo-version for the commit.
+// Note that branches and tags with names that are matched by other
+// query syntax cannot be selected this way. For example, the query
+// "v2" means the latest version starting with "v2", not the branch
+// named "v2".
 //
 // All queries prefer release versions to pre-release versions.
 // For example, "<v1.2.3" will prefer to return "v1.2.2"
@@ -2714,9 +2743,11 @@
 // 	GOSUMDB="sum.golang.org+<publickey>"
 // 	GOSUMDB="sum.golang.org+<publickey> https://sum.golang.org"
 //
-// The go command knows the public key of sum.golang.org; use of any other
-// database requires giving the public key explicitly. The URL defaults to
-// "https://" followed by the database name.
+// The go command knows the public key of sum.golang.org, and also that the name
+// sum.golang.google.cn (available inside mainland China) connects to the
+// sum.golang.org checksum database; use of any other database requires giving
+// the public key explicitly.
+// The URL defaults to "https://" followed by the database name.
 //
 // GOSUMDB defaults to "sum.golang.org", the Go checksum database run by Google.
 // See https://sum.golang.org/privacy for the service's privacy policy.

libgo/go/cmd/go/go_test.go

@@ -3177,6 +3177,12 @@ func TestGoTestFooTestWorks(t *testing.T) {
 	tg.run("test", "testdata/standalone_test.go")
 }
 
+func TestGoTestTestMainSeesTestingFlags(t *testing.T) {
+	tg := testgo(t)
+	defer tg.cleanup()
+	tg.run("test", "testdata/standalone_testmain_flag_test.go")
+}
+
 // Issue 22388
 func TestGoTestMainWithWrongSignature(t *testing.T) {
 	tg := testgo(t)

libgo/go/cmd/go/internal/cache/cache.go

@@ -173,7 +173,7 @@ func (c *Cache) get(id ActionID) (Entry, error) {
 		i++
 	}
 	tm, err := strconv.ParseInt(string(etime[i:]), 10, 64)
-	if err != nil || size < 0 {
+	if err != nil || tm < 0 {
 		return missing()
 	}
 
@@ -322,7 +322,7 @@ func (c *Cache) putIndexEntry(id ActionID, out OutputID, size int64, allowVerify
 	// in verify mode we are double-checking that the cache entries
 	// are entirely reproducible. As just noted, this may be unrealistic
 	// in some cases but the check is also useful for shaking out real bugs.
-	entry := []byte(fmt.Sprintf("v1 %x %x %20d %20d\n", id, out, size, time.Now().UnixNano()))
+	entry := fmt.Sprintf("v1 %x %x %20d %20d\n", id, out, size, time.Now().UnixNano())
 	if verify && allowVerify {
 		old, err := c.get(id)
 		if err == nil && (old.OutputID != out || old.Size != size) {
@@ -332,7 +332,28 @@ func (c *Cache) putIndexEntry(id ActionID, out OutputID, size int64, allowVerify
 		}
 	}
 	file := c.fileName(id, "a")
-	if err := ioutil.WriteFile(file, entry, 0666); err != nil {
+
+	// Copy file to cache directory.
+	mode := os.O_WRONLY | os.O_CREATE
+	f, err := os.OpenFile(file, mode, 0666)
+	if err != nil {
+		return err
+	}
+	_, err = f.WriteString(entry)
+	if err == nil {
+		// Truncate the file only *after* writing it.
+		// (This should be a no-op, but truncate just in case of previous corruption.)
+		//
+		// This differs from ioutil.WriteFile, which truncates to 0 *before* writing
+		// via os.O_TRUNC. Truncating only after writing ensures that a second write
+		// of the same content to the same file is idempotent, and does not — even
+		// temporarily! — undo the effect of the first write.
+		err = f.Truncate(int64(len(entry)))
+	}
+	if closeErr := f.Close(); err == nil {
+		err = closeErr
+	}
+	if err != nil {
 		// TODO(bcmills): This Remove potentially races with another go command writing to file.
 		// Can we eliminate it?
 		os.Remove(file)

libgo/go/cmd/go/internal/cfg/cfg.go

@@ -10,6 +10,7 @@ import (
 	"bytes"
 	"fmt"
 	"go/build"
+	"internal/cfg"
 	"io/ioutil"
 	"os"
 	"path/filepath"
@@ -221,61 +222,9 @@ func Getenv(key string) string {
 
 // CanGetenv reports whether key is a valid go/env configuration key.
 func CanGetenv(key string) bool {
-	return strings.Contains(knownEnv, "\t"+key+"\n")
+	return strings.Contains(cfg.KnownEnv, "\t"+key+"\n")
 }
 
-var knownEnv = `
-	AR
-	CC
-	CGO_CFLAGS
-	CGO_CFLAGS_ALLOW
-	CGO_CFLAGS_DISALLOW
-	CGO_CPPFLAGS
-	CGO_CPPFLAGS_ALLOW
-	CGO_CPPFLAGS_DISALLOW
-	CGO_CXXFLAGS
-	CGO_CXXFLAGS_ALLOW
-	CGO_CXXFLAGS_DISALLOW
-	CGO_ENABLED
-	CGO_FFLAGS
-	CGO_FFLAGS_ALLOW
-	CGO_FFLAGS_DISALLOW
-	CGO_LDFLAGS
-	CGO_LDFLAGS_ALLOW
-	CGO_LDFLAGS_DISALLOW
-	CXX
-	FC
-	GCCGO
-	GO111MODULE
-	GO386
-	GOARCH
-	GOARM
-	GOBIN
-	GOCACHE
-	GOENV
-	GOEXE
-	GOFLAGS
-	GOGCCFLAGS
-	GOHOSTARCH
-	GOHOSTOS
-	GOMIPS
-	GOMIPS64
-	GONOPROXY
-	GONOSUMDB
-	GOOS
-	GOPATH
-	GOPPC64
-	GOPRIVATE
-	GOPROXY
-	GOROOT
-	GOSUMDB
-	GOTMPDIR
-	GOTOOLDIR
-	GOWASM
-	GO_EXTLINK_ENABLED
-	PKG_CONFIG
-`
-
 var (
 	GOROOT       = BuildContext.GOROOT
 	GOBIN        = Getenv("GOBIN")

libgo/go/cmd/go/internal/get/vcs.go

@@ -164,8 +164,14 @@ var vcsGit = &vcsCmd{
 	// See golang.org/issue/9032.
 	tagSyncDefault: []string{"submodule update --init --recursive"},
 
-	scheme:     []string{"git", "https", "http", "git+ssh", "ssh"},
-	pingCmd:    "ls-remote -- {scheme}://{repo}",
+	scheme: []string{"git", "https", "http", "git+ssh", "ssh"},
+
+	// Leave out the '--' separator in the ls-remote command: git 2.7.4 does not
+	// support such a separator for that command, and this use should be safe
+	// without it because the {scheme} value comes from the predefined list above.
+	// See golang.org/issue/33836.
+	pingCmd: "ls-remote {scheme}://{repo}",
+
 	remoteRepo: gitRemoteRepo,
 }
 

libgo/go/cmd/go/internal/help/help.go

@@ -63,7 +63,7 @@ Args:
 		// helpSuccess is the help command using as many args as possible that would succeed.
 		helpSuccess := "go help"
 		if i > 0 {
-			helpSuccess = " " + strings.Join(args[:i], " ")
+			helpSuccess += " " + strings.Join(args[:i], " ")
 		}
 		fmt.Fprintf(os.Stderr, "go help %s: unknown help topic. Run '%s'.\n", strings.Join(args, " "), helpSuccess)
 		base.SetExitStatus(2) // failed at 'go help cmd'

libgo/go/cmd/go/internal/help/helpdoc.go

@@ -493,6 +493,9 @@ General-purpose environment variables:
 	GOCACHE
 		The directory where the go command will store cached
 		information for reuse in future builds.
+	GODEBUG
+		Enable various debugging facilities. See 'go doc runtime'
+		for details.
 	GOENV
 		The location of the Go environment configuration file.
 		Cannot be set using 'go env -w'.

libgo/go/cmd/go/internal/list/list.go

@@ -390,7 +390,7 @@ func runList(cmd *base.Command, args []string) {
 		if !*listE {
 			for _, m := range mods {
 				if m.Error != nil {
-					base.Errorf("go list -m %s: %v", m.Path, m.Error.Err)
+					base.Errorf("go list -m: %v", m.Error.Err)
 				}
 			}
 			base.ExitIfErrors()
@@ -459,7 +459,7 @@ func runList(cmd *base.Command, args []string) {
 				}
 				if pmain != nil {
 					pkgs = append(pkgs, pmain)
-					data := pmain.Internal.TestmainGo
+					data := *pmain.Internal.TestmainGo
 					h := cache.NewHash("testmain")
 					h.Write([]byte("testmain\n"))
 					h.Write(data)

libgo/go/cmd/go/internal/load/pkg.go

@@ -64,7 +64,7 @@ type PackagePublic struct {
 	Doc           string                `json:",omitempty"` // package documentation string
 	Target        string                `json:",omitempty"` // installed target for this package (may be executable)
 	Shlib         string                `json:",omitempty"` // the shared library that contains this package (only set when -linkshared)
-	Root          string                `json:",omitempty"` // Go root or Go path dir containing this package
+	Root          string                `json:",omitempty"` // Go root, Go path dir, or module root dir containing this package
 	ConflictDir   string                `json:",omitempty"` // Dir is hidden by this other directory
 	ForTest       string                `json:",omitempty"` // package is only for use in named test
 	Export        string                `json:",omitempty"` // file containing export data (set by go list -export)
@@ -177,8 +177,7 @@ type PackageInternal struct {
 	OmitDebug         bool                 // tell linker not to write debug information
 	GobinSubdir       bool                 // install target would be subdir of GOBIN
 	BuildInfo         string               // add this info to package main
-	TestinginitGo     []byte               // content for _testinginit.go
-	TestmainGo        []byte               // content for _testmain.go
+	TestmainGo        *[]byte              // content for _testmain.go
 
 	Asmflags   []string // -asmflags for this package
 	Gcflags    []string // -gcflags for this package
@@ -647,9 +646,14 @@ func loadPackageData(path, parentPath, parentDir, parentRoot string, parentIsStd
 				buildMode = build.ImportComment
 			}
 			data.p, data.err = cfg.BuildContext.ImportDir(r.dir, buildMode)
+			if data.p.Root == "" && cfg.ModulesEnabled {
+				if info := ModPackageModuleInfo(path); info != nil {
+					data.p.Root = info.Dir
+				}
+			}
 		} else if r.err != nil {
 			data.p = new(build.Package)
-			data.err = fmt.Errorf("unknown import path %q: %v", r.path, r.err)
+			data.err = r.err
 		} else if cfg.ModulesEnabled && path != "unsafe" {
 			data.p = new(build.Package)
 			data.err = fmt.Errorf("unknown import path %q: internal error: module loader did not resolve import", r.path)

libgo/go/cmd/go/internal/load/test.go

@@ -102,7 +102,6 @@ func TestPackagesAndErrors(p *Package, cover *TestCover) (pmain, ptest, pxtest *
 	var stk ImportStack
 	stk.Push(p.ImportPath + " (test)")
 	rawTestImports := str.StringList(p.TestImports)
-	var ptestImportsTesting, pxtestImportsTesting bool
 	for i, path := range p.TestImports {
 		p1 := loadImport(pre, path, p.Dir, p, &stk, p.Internal.Build.TestImportPos[path], ResolveImport)
 		if str.Contains(p1.Deps, p.ImportPath) || p1.ImportPath == p.ImportPath {
@@ -117,9 +116,6 @@ func TestPackagesAndErrors(p *Package, cover *TestCover) (pmain, ptest, pxtest *
 		}
 		p.TestImports[i] = p1.ImportPath
 		imports = append(imports, p1)
-		if path == "testing" {
-			ptestImportsTesting = true
-		}
 	}
 	stk.Pop()
 	stk.Push(p.ImportPath + "_test")
@@ -133,9 +129,6 @@ func TestPackagesAndErrors(p *Package, cover *TestCover) (pmain, ptest, pxtest *
 			ximports = append(ximports, p1)
 		}
 		p.XTestImports[i] = p1.ImportPath
-		if path == "testing" {
-			pxtestImportsTesting = true
-		}
 	}
 	stk.Pop()
 
@@ -145,9 +138,6 @@ func TestPackagesAndErrors(p *Package, cover *TestCover) (pmain, ptest, pxtest *
 		*ptest = *p
 		ptest.Error = ptestErr
 		ptest.ForTest = p.ImportPath
-		if ptestImportsTesting {
-			ptest.Internal.TestinginitGo = formatTestinginit(p)
-		}
 		ptest.GoFiles = nil
 		ptest.GoFiles = append(ptest.GoFiles, p.GoFiles...)
 		ptest.GoFiles = append(ptest.GoFiles, p.TestGoFiles...)
@@ -212,9 +202,6 @@ func TestPackagesAndErrors(p *Package, cover *TestCover) (pmain, ptest, pxtest *
 				Gccgoflags: p.Internal.Gccgoflags,
 			},
 		}
-		if pxtestImportsTesting {
-			pxtest.Internal.TestinginitGo = formatTestinginit(pxtest)
-		}
 		if pxtestNeedsPtest {
 			pxtest.Internal.Imports = append(pxtest.Internal.Imports, ptest)
 		}
@@ -337,7 +324,9 @@ func TestPackagesAndErrors(p *Package, cover *TestCover) (pmain, ptest, pxtest *
 	if err != nil && pmain.Error == nil {
 		pmain.Error = &PackageError{Err: err.Error()}
 	}
-	pmain.Internal.TestmainGo = data
+	if data != nil {
+		pmain.Internal.TestmainGo = &data
+	}
 
 	return pmain, ptest, pxtest
 }
@@ -485,15 +474,6 @@ func loadTestFuncs(ptest *Package) (*testFuncs, error) {
 	return t, err
 }
 
-// formatTestinginit returns the content of the _testinginit.go file for p.
-func formatTestinginit(p *Package) []byte {
-	var buf bytes.Buffer
-	if err := testinginitTmpl.Execute(&buf, p); err != nil {
-		panic("testinginit template execution failed") // shouldn't be possible
-	}
-	return buf.Bytes()
-}
-
 // formatTestmain returns the content of the _testmain.go file for t.
 func formatTestmain(t *testFuncs) ([]byte, error) {
 	var buf bytes.Buffer
@@ -623,23 +603,6 @@ func checkTestFunc(fn *ast.FuncDecl, arg string) error {
 	return nil
 }
 
-var testinginitTmpl = lazytemplate.New("init", `
-package {{.Name}}
-
-import _go_testing "testing"
-
-{{/*
-Call testing.Init before any other user initialization code runs.
-(This file is passed to the compiler first.)
-This provides the illusion of the old behavior where testing flags
-were registered as part of the testing package's initialization.
-*/}}
-var _ = func() bool {
-	_go_testing.Init()
-	return true
-}()
-`)
-
 var testmainTmpl = lazytemplate.New("main", `
 // Code generated by 'go test'. DO NOT EDIT.
 

libgo/go/cmd/go/internal/modcmd/download.go

@@ -43,6 +43,7 @@ corresponding to this Go struct:
         Dir      string // absolute path to cached source root directory
         Sum      string // checksum for path, version (as in go.sum)
         GoModSum string // checksum for go.mod (as in go.sum)
+        Latest   bool   // would @latest resolve to this version?
     }
 
 See 'go help modules' for more about module queries.
@@ -65,6 +66,7 @@ type moduleJSON struct {
 	Dir      string `json:",omitempty"`
 	Sum      string `json:",omitempty"`
 	GoModSum string `json:",omitempty"`
+	Latest   bool   `json:",omitempty"`
 }
 
 func runDownload(cmd *base.Command, args []string) {
@@ -87,7 +89,8 @@ func runDownload(cmd *base.Command, args []string) {
 		if info.Replace != nil {
 			info = info.Replace
 		}
-		if info.Version == "" {
+		if info.Version == "" && info.Error == nil {
+			// main module
 			continue
 		}
 		m := &moduleJSON{
@@ -95,9 +98,38 @@ func runDownload(cmd *base.Command, args []string) {
 			Version: info.Version,
 		}
 		mods = append(mods, m)
+		if info.Error != nil {
+			m.Error = info.Error.Err
+			continue
+		}
 		work.Add(m)
 	}
 
+	latest := map[string]string{} // path → version
+	if *downloadJSON {
+		// We need to populate the Latest field, but if the main module depends on a
+		// version newer than latest — or if the version requested on the command
+		// line is itself newer than latest — that's not trivial to determine from
+		// the info returned by ListModules. Instead, we issue a separate
+		// ListModules request for "latest", which should be inexpensive relative to
+		// downloading the modules.
+		var latestArgs []string
+		for _, m := range mods {
+			if m.Error != "" {
+				continue
+			}
+			latestArgs = append(latestArgs, m.Path+"@latest")
+		}
+
+		if len(latestArgs) > 0 {
+			for _, info := range modload.ListModules(latestArgs, listU, listVersions) {
+				if info.Version != "" {
+					latest[info.Path] = info.Version
+				}
+			}
+		}
+	}
+
 	work.Do(10, func(item interface{}) {
 		m := item.(*moduleJSON)
 		var err error
@@ -128,6 +160,9 @@ func runDownload(cmd *base.Command, args []string) {
 			m.Error = err.Error()
 			return
 		}
+		if latest[m.Path] == m.Version {
+			m.Latest = true
+		}
 	})
 
 	if *downloadJSON {
@@ -144,7 +179,7 @@ func runDownload(cmd *base.Command, args []string) {
 	} else {
 		for _, m := range mods {
 			if m.Error != "" {
-				base.Errorf("%s@%s: %s\n", m.Path, m.Version, m.Error)
+				base.Errorf("%s", m.Error)
 			}
 		}
 		base.ExitIfErrors()

libgo/go/cmd/go/internal/modfetch/codehost/vcs.go

@@ -341,7 +341,9 @@ func (r *vcsRepo) Stat(rev string) (*RevInfo, error) {
 }
 
 func (r *vcsRepo) fetch() {
-	_, r.fetchErr = Run(r.dir, r.cmd.fetch)
+	if len(r.cmd.fetch) > 0 {
+		_, r.fetchErr = Run(r.dir, r.cmd.fetch)
+	}
 }
 
 func (r *vcsRepo) statLocal(rev string) (*RevInfo, error) {

libgo/go/cmd/go/internal/modfetch/coderepo.go

@@ -31,7 +31,7 @@ type codeRepo struct {
 	codeRoot string
 	// codeDir is the directory (relative to root) at which we expect to find the module.
 	// If pathMajor is non-empty and codeRoot is not the full modPath,
-	// then we look in both codeDir and codeDir+modPath
+	// then we look in both codeDir and codeDir/pathMajor[1:].
 	codeDir string
 
 	// pathMajor is the suffix of modPath that indicates its major version,
@@ -192,7 +192,13 @@ func (r *codeRepo) Stat(rev string) (*RevInfo, error) {
 	codeRev := r.revToRev(rev)
 	info, err := r.code.Stat(codeRev)
 	if err != nil {
-		return nil, err
+		return nil, &module.ModuleError{
+			Path: r.modPath,
+			Err: &module.InvalidVersionError{
+				Version: rev,
+				Err:     err,
+			},
+		}
 	}
 	return r.convert(info, rev)
 }
@@ -248,20 +254,25 @@ func (r *codeRepo) convert(info *codehost.RevInfo, statVers string) (*RevInfo, e
 	// exist as required by info2.Version and the module path represented by r.
 	checkGoMod := func() (*RevInfo, error) {
 		// If r.codeDir is non-empty, then the go.mod file must exist: the module
-		// author, not the module consumer, gets to decide how to carve up the repo
+		// author — not the module consumer, — gets to decide how to carve up the repo
 		// into modules.
-		if r.codeDir != "" {
-			_, _, _, err := r.findDir(info2.Version)
-			if err != nil {
-				// TODO: It would be nice to return an error like "not a module".
-				// Right now we return "missing go.mod", which is a little confusing.
-				return nil, &module.ModuleError{
-					Path: r.modPath,
-					Err: &module.InvalidVersionError{
-						Version: info2.Version,
-						Err:     notExistError(err.Error()),
-					},
-				}
+		//
+		// Conversely, if the go.mod file exists, the module author — not the module
+		// consumer — gets to determine the module's path
+		//
+		// r.findDir verifies both of these conditions. Execute it now so that
+		// r.Stat will correctly return a notExistError if the go.mod location or
+		// declared module path doesn't match.
+		_, _, _, err := r.findDir(info2.Version)
+		if err != nil {
+			// TODO: It would be nice to return an error like "not a module".
+			// Right now we return "missing go.mod", which is a little confusing.
+			return nil, &module.ModuleError{
+				Path: r.modPath,
+				Err: &module.InvalidVersionError{
+					Version: info2.Version,
+					Err:     notExistError(err.Error()),
+				},
 			}
 		}
 
@@ -474,6 +485,11 @@ func (r *codeRepo) validatePseudoVersion(info *codehost.RevInfo, version string)
 		return fmt.Errorf("does not match version-control timestamp (%s)", info.Time.UTC().Format(time.RFC3339))
 	}
 
+	tagPrefix := ""
+	if r.codeDir != "" {
+		tagPrefix = r.codeDir + "/"
+	}
+
 	// A pseudo-version should have a precedence just above its parent revisions,
 	// and no higher. Otherwise, it would be possible for library authors to "pin"
 	// dependency versions (and bypass the usual minimum version selection) by
@@ -499,11 +515,26 @@ func (r *codeRepo) validatePseudoVersion(info *codehost.RevInfo, version string)
 			return fmt.Errorf("major version without preceding tag must be v0, not v1")
 		}
 		return nil
-	}
-
-	tagPrefix := ""
-	if r.codeDir != "" {
-		tagPrefix = r.codeDir + "/"
+	} else {
+		for _, tag := range info.Tags {
+			versionOnly := strings.TrimPrefix(tag, tagPrefix)
+			if versionOnly == base {
+				// The base version is canonical, so if the version from the tag is
+				// literally equal (not just equivalent), then the tag is canonical too.
+				//
+				// We allow pseudo-versions to be derived from non-canonical tags on the
+				// same commit, so that tags like "v1.1.0+some-metadata" resolve as
+				// close as possible to the canonical version ("v1.1.0") while still
+				// enforcing a total ordering ("v1.1.1-0.[…]" with a unique suffix).
+				//
+				// However, canonical tags already have a total ordering, so there is no
+				// reason not to use the canonical tag directly, and we know that the
+				// canonical tag must already exist because the pseudo-version is
+				// derived from it. In that case, referring to the revision by a
+				// pseudo-version derived from its own canonical tag is just confusing.
+				return fmt.Errorf("tag (%s) found on revision %s is already canonical, so should not be replaced with a pseudo-version derived from that tag", tag, rev)
+			}
+		}
 	}
 
 	tags, err := r.code.Tags(tagPrefix + base)
@@ -571,6 +602,10 @@ func (r *codeRepo) versionToRev(version string) (rev string, err error) {
 	return r.revToRev(version), nil
 }
 
+// findDir locates the directory within the repo containing the module.
+//
+// If r.pathMajor is non-empty, this can be either r.codeDir or — if a go.mod
+// file exists — r.codeDir/r.pathMajor[1:].
 func (r *codeRepo) findDir(version string) (rev, dir string, gomod []byte, err error) {
 	rev, err = r.versionToRev(version)
 	if err != nil {

libgo/go/cmd/go/internal/modfetch/coderepo_test.go

@@ -86,6 +86,26 @@ var codeRepoTests = []codeRepoTest{
 	{
 		vcs:     "git",
 		path:    "github.com/rsc/vgotest1",
+		rev:     "v0.0.0-20180219231006-80d85c5d4d17",
+		version: "v0.0.0-20180219231006-80d85c5d4d17",
+		name:    "80d85c5d4d17598a0e9055e7c175a32b415d6128",
+		short:   "80d85c5d4d17",
+		time:    time.Date(2018, 2, 19, 23, 10, 6, 0, time.UTC),
+		zip: []string{
+			"LICENSE",
+			"README.md",
+			"pkg/p.go",
+		},
+	},
+	{
+		vcs:  "git",
+		path: "github.com/rsc/vgotest1",
+		rev:  "v0.0.1-0.20180219231006-80d85c5d4d17",
+		err:  `github.com/rsc/vgotest1@v0.0.1-0.20180219231006-80d85c5d4d17: invalid pseudo-version: tag (v0.0.0) found on revision 80d85c5d4d17 is already canonical, so should not be replaced with a pseudo-version derived from that tag`,
+	},
+	{
+		vcs:     "git",
+		path:    "github.com/rsc/vgotest1",
 		rev:     "v1.0.0",
 		version: "v1.0.0",
 		name:    "80d85c5d4d17598a0e9055e7c175a32b415d6128",
@@ -105,7 +125,7 @@ var codeRepoTests = []codeRepoTest{
 		name:    "45f53230a74ad275c7127e117ac46914c8126160",
 		short:   "45f53230a74a",
 		time:    time.Date(2018, 7, 19, 1, 21, 27, 0, time.UTC),
-		ziperr:  "missing github.com/rsc/vgotest1/go.mod and .../v2/go.mod at revision v2.0.0",
+		err:     "missing github.com/rsc/vgotest1/go.mod and .../v2/go.mod at revision v2.0.0",
 	},
 	{
 		vcs:     "git",
@@ -136,15 +156,14 @@ var codeRepoTests = []codeRepoTest{
 		},
 	},
 	{
-		vcs:      "git",
-		path:     "github.com/rsc/vgotest1/v2",
-		rev:      "45f53230a",
-		version:  "v2.0.0",
-		name:     "45f53230a74ad275c7127e117ac46914c8126160",
-		short:    "45f53230a74a",
-		time:     time.Date(2018, 7, 19, 1, 21, 27, 0, time.UTC),
-		gomoderr: "missing github.com/rsc/vgotest1/go.mod and .../v2/go.mod at revision v2.0.0",
-		ziperr:   "missing github.com/rsc/vgotest1/go.mod and .../v2/go.mod at revision v2.0.0",
+		vcs:     "git",
+		path:    "github.com/rsc/vgotest1/v2",
+		rev:     "45f53230a",
+		version: "v2.0.0",
+		name:    "45f53230a74ad275c7127e117ac46914c8126160",
+		short:   "45f53230a74a",
+		time:    time.Date(2018, 7, 19, 1, 21, 27, 0, time.UTC),
+		err:     "missing github.com/rsc/vgotest1/go.mod and .../v2/go.mod at revision v2.0.0",
 	},
 	{
 		vcs:     "git",
@@ -154,7 +173,7 @@ var codeRepoTests = []codeRepoTest{
 		name:    "80d85c5d4d17598a0e9055e7c175a32b415d6128",
 		short:   "80d85c5d4d17",
 		time:    time.Date(2018, 2, 19, 23, 10, 6, 0, time.UTC),
-		ziperr:  "missing github.com/rsc/vgotest1/go.mod and .../v54321/go.mod at revision 80d85c5d4d17",
+		err:     "missing github.com/rsc/vgotest1/go.mod and .../v54321/go.mod at revision 80d85c5d4d17",
 	},
 	{
 		vcs:  "git",
@@ -210,24 +229,24 @@ var codeRepoTests = []codeRepoTest{
 		gomod:   "module \"github.com/rsc/vgotest1/v2\" // root go.mod\n",
 	},
 	{
-		vcs:      "git",
-		path:     "github.com/rsc/vgotest1/v2",
-		rev:      "v2.0.3",
-		version:  "v2.0.3",
-		name:     "f18795870fb14388a21ef3ebc1d75911c8694f31",
-		short:    "f18795870fb1",
-		time:     time.Date(2018, 2, 19, 23, 16, 4, 0, time.UTC),
-		gomoderr: "github.com/rsc/vgotest1/v2/go.mod has non-.../v2 module path \"github.com/rsc/vgotest\" at revision v2.0.3",
+		vcs:     "git",
+		path:    "github.com/rsc/vgotest1/v2",
+		rev:     "v2.0.3",
+		version: "v2.0.3",
+		name:    "f18795870fb14388a21ef3ebc1d75911c8694f31",
+		short:   "f18795870fb1",
+		time:    time.Date(2018, 2, 19, 23, 16, 4, 0, time.UTC),
+		err:     "github.com/rsc/vgotest1/v2/go.mod has non-.../v2 module path \"github.com/rsc/vgotest\" at revision v2.0.3",
 	},
 	{
-		vcs:      "git",
-		path:     "github.com/rsc/vgotest1/v2",
-		rev:      "v2.0.4",
-		version:  "v2.0.4",
-		name:     "1f863feb76bc7029b78b21c5375644838962f88d",
-		short:    "1f863feb76bc",
-		time:     time.Date(2018, 2, 20, 0, 3, 38, 0, time.UTC),
-		gomoderr: "github.com/rsc/vgotest1/go.mod and .../v2/go.mod both have .../v2 module paths at revision v2.0.4",
+		vcs:     "git",
+		path:    "github.com/rsc/vgotest1/v2",
+		rev:     "v2.0.4",
+		version: "v2.0.4",
+		name:    "1f863feb76bc7029b78b21c5375644838962f88d",
+		short:   "1f863feb76bc",
+		time:    time.Date(2018, 2, 20, 0, 3, 38, 0, time.UTC),
+		err:     "github.com/rsc/vgotest1/go.mod and .../v2/go.mod both have .../v2 module paths at revision v2.0.4",
 	},
 	{
 		vcs:     "git",
@@ -504,6 +523,7 @@ func TestCodeRepo(t *testing.T) {
 					tt.name = remap(tt.name, m)
 					tt.short = remap(tt.short, m)
 					tt.rev = remap(tt.rev, m)
+					tt.err = remap(tt.err, m)
 					tt.gomoderr = remap(tt.gomoderr, m)
 					tt.ziperr = remap(tt.ziperr, m)
 					t.Run(strings.ReplaceAll(tt.path, "/", "_")+"/"+tt.rev, f(tt))
@@ -515,7 +535,7 @@ func TestCodeRepo(t *testing.T) {
 }
 
 var hgmap = map[string]string{
-	"github.com/rsc/vgotest1/":                 "vcs-test.golang.org/hg/vgotest1.hg/",
+	"github.com/rsc/vgotest1":                  "vcs-test.golang.org/hg/vgotest1.hg",
 	"f18795870fb14388a21ef3ebc1d75911c8694f31": "a9ad6d1d14eb544f459f446210c7eb3b009807c6",
 	"ea65f87c8f52c15ea68f3bdd9925ef17e20d91e9": "f1fc0f22021b638d073d31c752847e7bf385def7",
 	"b769f2de407a4db81af9c5de0a06016d60d2ea09": "92c7eb888b4fac17f1c6bd2e1060a1b881a3b832",
@@ -631,9 +651,14 @@ var latestTests = []struct {
 		err:  "no commits",
 	},
 	{
-		vcs:     "git",
-		path:    "github.com/rsc/vgotest1",
-		version: "v0.0.0-20180219223237-a08abb797a67",
+		vcs:  "git",
+		path: "github.com/rsc/vgotest1",
+		err:  `github.com/rsc/vgotest1@v0.0.0-20180219223237-a08abb797a67: invalid version: go.mod has post-v0 module path "github.com/vgotest1/v2" at revision a08abb797a67`,
+	},
+	{
+		vcs:  "git",
+		path: "github.com/rsc/vgotest1/v2",
+		err:  `github.com/rsc/vgotest1/v2@v2.0.0-20180219223237-a08abb797a67: invalid version: github.com/rsc/vgotest1/go.mod and .../v2/go.mod both have .../v2 module paths at revision a08abb797a67`,
 	},
 	{
 		vcs:  "git",
@@ -641,6 +666,16 @@ var latestTests = []struct {
 		err:  "github.com/rsc/vgotest1/subdir@v0.0.0-20180219223237-a08abb797a67: invalid version: missing github.com/rsc/vgotest1/subdir/go.mod at revision a08abb797a67",
 	},
 	{
+		vcs:     "git",
+		path:    "vcs-test.golang.org/git/commit-after-tag.git",
+		version: "v1.0.1-0.20190715211727-b325d8217783",
+	},
+	{
+		vcs:     "git",
+		path:    "vcs-test.golang.org/git/no-tags.git",
+		version: "v0.0.0-20190715212047-e706ba1d9f6d",
+	},
+	{
 		vcs:     "mod",
 		path:    "swtch.com/testmod",
 		version: "v1.1.1",

libgo/go/cmd/go/internal/modfetch/fetch.go

@@ -701,9 +701,11 @@ to use and optionally its public key and URL, as in:
 	GOSUMDB="sum.golang.org+<publickey>"
 	GOSUMDB="sum.golang.org+<publickey> https://sum.golang.org"
 
-The go command knows the public key of sum.golang.org; use of any other
-database requires giving the public key explicitly. The URL defaults to
-"https://" followed by the database name.
+The go command knows the public key of sum.golang.org, and also that the name
+sum.golang.google.cn (available inside mainland China) connects to the
+sum.golang.org checksum database; use of any other database requires giving
+the public key explicitly.
+The URL defaults to "https://" followed by the database name.
 
 GOSUMDB defaults to "sum.golang.org", the Go checksum database run by Google.
 See https://sum.golang.org/privacy for the service's privacy policy.

libgo/go/cmd/go/internal/modfetch/proxy.go

@@ -345,7 +345,9 @@ func (p *proxyRepo) Stat(rev string) (*RevInfo, error) {
 func (p *proxyRepo) Latest() (*RevInfo, error) {
 	data, err := p.getBytes("@latest")
 	if err != nil {
-		// TODO return err if not 404
+		if !errors.Is(err, os.ErrNotExist) {
+			return nil, p.versionError("", err)
+		}
 		return p.latest()
 	}
 	info := new(RevInfo)

libgo/go/cmd/go/internal/modfetch/repo.go

@@ -240,7 +240,7 @@ func lookup(proxy, path string) (r Repo, err error) {
 
 var (
 	errModVendor       = errors.New("module lookup disabled by -mod=vendor")
-	errProxyOff        = errors.New("module lookup disabled by GOPROXY=off")
+	errProxyOff        = notExistError("module lookup disabled by GOPROXY=off")
 	errNoproxy   error = notExistError("disabled by GOPRIVATE/GONOPROXY")
 	errUseProxy  error = notExistError("path does not match GOPRIVATE/GONOPROXY")
 )

libgo/go/cmd/go/internal/modfetch/sumdb.go

@@ -60,7 +60,17 @@ func dbDial() (dbName string, db *sumweb.Conn, err error) {
 	// $GOSUMDB can be "key" or "key url",
 	// and the key can be a full verifier key
 	// or a host on our list of known keys.
-	key := strings.Fields(cfg.GOSUMDB)
+
+	// Special case: sum.golang.google.cn
+	// is an alias, reachable inside mainland China,
+	// for sum.golang.org. If there are more
+	// of these we should add a map like knownGOSUMDB.
+	gosumdb := cfg.GOSUMDB
+	if gosumdb == "sum.golang.google.cn" {
+		gosumdb = "sum.golang.org https://sum.golang.google.cn"
+	}
+
+	key := strings.Fields(gosumdb)
 	if len(key) >= 1 {
 		if k := knownGOSUMDB[key[0]]; k != "" {
 			key[0] = k
@@ -232,10 +242,10 @@ func (*dbClient) WriteConfig(file string, old, new []byte) error {
 }
 
 // ReadCache reads cached lookups or tiles from
-// GOPATH/pkg/mod/download/cache/sumdb,
+// GOPATH/pkg/mod/cache/download/sumdb,
 // which will be deleted by "go clean -modcache".
 func (*dbClient) ReadCache(file string) ([]byte, error) {
-	targ := filepath.Join(PkgMod, "download/cache/sumdb", file)
+	targ := filepath.Join(PkgMod, "cache/download/sumdb", file)
 	data, err := lockedfile.Read(targ)
 	// lockedfile.Write does not atomically create the file with contents.
 	// There is a moment between file creation and locking the file for writing,
@@ -249,7 +259,7 @@ func (*dbClient) ReadCache(file string) ([]byte, error) {
 
 // WriteCache updates cached lookups or tiles.
 func (*dbClient) WriteCache(file string, data []byte) {
-	targ := filepath.Join(PkgMod, "download/cache/sumdb", file)
+	targ := filepath.Join(PkgMod, "cache/download/sumdb", file)
 	os.MkdirAll(filepath.Dir(targ), 0777)
 	lockedfile.Write(targ, bytes.NewReader(data), 0666)
 }

libgo/go/cmd/go/internal/modload/build.go

@@ -79,7 +79,7 @@ func addUpdate(m *modinfo.ModulePublic) {
 		return
 	}
 
-	if info, err := Query(m.Path, "latest", m.Version, Allowed); err == nil && semver.Compare(info.Version, m.Version) > 0 {
+	if info, err := Query(m.Path, "upgrade", m.Version, Allowed); err == nil && semver.Compare(info.Version, m.Version) > 0 {
 		m.Update = &modinfo.ModulePublic{
 			Path:    m.Path,
 			Version: info.Version,

libgo/go/cmd/go/internal/modload/help.go

@@ -231,12 +231,25 @@ evaluates to the available tagged version nearest to the comparison target
 The string "latest" matches the latest available tagged version,
 or else the underlying source repository's latest untagged revision.
 
-A revision identifier for the underlying source repository,
-such as a commit hash prefix, revision tag, or branch name,
-selects that specific code revision. If the revision is
-also tagged with a semantic version, the query evaluates to
-that semantic version. Otherwise the query evaluates to a
-pseudo-version for the commit.
+The string "upgrade" is like "latest", but if the module is
+currently required at a later version than the version "latest"
+would select (for example, a newer pre-release version), "upgrade"
+will select the later version instead.
+
+The string "patch" matches the latest available tagged version
+of a module with the same major and minor version numbers as the
+currently required version. If no version is currently required,
+"patch" is equivalent to "latest".
+
+A revision identifier for the underlying source repository, such as
+a commit hash prefix, revision tag, or branch name, selects that
+specific code revision. If the revision is also tagged with a
+semantic version, the query evaluates to that semantic version.
+Otherwise the query evaluates to a pseudo-version for the commit.
+Note that branches and tags with names that are matched by other
+query syntax cannot be selected this way. For example, the query
+"v2" means the latest version starting with "v2", not the branch
+named "v2".
 
 All queries prefer release versions to pre-release versions.
 For example, "<v1.2.3" will prefer to return "v1.2.2"

libgo/go/cmd/go/internal/modload/import.go

@@ -22,6 +22,7 @@ import (
 	"cmd/go/internal/par"
 	"cmd/go/internal/search"
 	"cmd/go/internal/semver"
+	"cmd/go/internal/str"
 )
 
 type ImportMissingError struct {
@@ -35,6 +36,9 @@ type ImportMissingError struct {
 
 func (e *ImportMissingError) Error() string {
 	if e.Module.Path == "" {
+		if str.HasPathPrefix(e.ImportPath, "cmd") {
+			return fmt.Sprintf("package %s is not in GOROOT (%s)", e.ImportPath, filepath.Join(cfg.GOROOT, "src", e.ImportPath))
+		}
 		return "cannot find module providing package " + e.ImportPath
 	}
 	return "missing module for import: " + e.Module.Path + "@" + e.Module.Version + " provides " + e.ImportPath
@@ -74,6 +78,9 @@ func Import(path string) (m module.Version, dir string, err error) {
 		dir := filepath.Join(cfg.GOROOT, "src", path)
 		return module.Version{}, dir, nil
 	}
+	if str.HasPathPrefix(path, "cmd") {
+		return module.Version{}, "", &ImportMissingError{ImportPath: path}
+	}
 
 	// -mod=vendor is special.
 	// Everything must be in the main module or the main module's vendor directory.

libgo/go/cmd/go/internal/modload/list.go

@@ -5,6 +5,7 @@
 package modload
 
 import (
+	"errors"
 	"fmt"
 	"os"
 	"strings"
@@ -70,9 +71,7 @@ func listModules(args []string, listVersions bool) []*modinfo.ModulePublic {
 				mods = append(mods, &modinfo.ModulePublic{
 					Path:    path,
 					Version: vers,
-					Error: &modinfo.ModuleError{
-						Err: err.Error(),
-					},
+					Error:   modinfoError(path, vers, err),
 				})
 				continue
 			}
@@ -116,19 +115,15 @@ func listModules(args []string, listVersions bool) []*modinfo.ModulePublic {
 						mods = append(mods, moduleInfo(module.Version{Path: arg, Version: info.Version}, false))
 					} else {
 						mods = append(mods, &modinfo.ModulePublic{
-							Path: arg,
-							Error: &modinfo.ModuleError{
-								Err: err.Error(),
-							},
+							Path:  arg,
+							Error: modinfoError(arg, "", err),
 						})
 					}
 					continue
 				}
 				mods = append(mods, &modinfo.ModulePublic{
-					Path: arg,
-					Error: &modinfo.ModuleError{
-						Err: fmt.Sprintf("module %q is not a known dependency", arg),
-					},
+					Path:  arg,
+					Error: modinfoError(arg, "", errors.New("not a known dependency")),
 				})
 			} else {
 				fmt.Fprintf(os.Stderr, "warning: pattern %q matched no module dependencies\n", arg)
@@ -138,3 +133,21 @@ func listModules(args []string, listVersions bool) []*modinfo.ModulePublic {
 
 	return mods
 }
+
+// modinfoError wraps an error to create an error message in
+// modinfo.ModuleError with minimal redundancy.
+func modinfoError(path, vers string, err error) *modinfo.ModuleError {
+	var nerr *NoMatchingVersionError
+	var merr *module.ModuleError
+	if errors.As(err, &nerr) {
+		// NoMatchingVersionError contains the query, so we don't mention the
+		// query again in ModuleError.
+		err = &module.ModuleError{Path: path, Err: err}
+	} else if !errors.As(err, &merr) {
+		// If the error does not contain path and version, wrap it in a
+		// module.ModuleError.
+		err = &module.ModuleError{Path: path, Version: vers, Err: err}
+	}
+
+	return &modinfo.ModuleError{Err: err.Error()}
+}

libgo/go/cmd/go/internal/modload/load.go

@@ -100,11 +100,31 @@ func ImportPathsQuiet(patterns []string, tags map[string]bool) []*search.Match {
 						dir = filepath.Clean(dir)
 					}
 
+					// golang.org/issue/32917: We should resolve a relative path to a
+					// package path only if the relative path actually contains the code
+					// for that package.
+					if !dirContainsPackage(dir) {
+						// If we're outside of a module, ensure that the failure mode
+						// indicates that.
+						ModRoot()
+
+						// If the directory is local but does not exist, don't return it
+						// while loader is iterating, since this might trigger a fetch.
+						// After loader is done iterating, we still need to return the
+						// path, so that "go list -e" produces valid output.
+						if !iterating {
+							// We don't have a valid path to resolve to, so report the
+							// unresolved path.
+							m.Pkgs = append(m.Pkgs, pkg)
+						}
+						continue
+					}
+
 					// Note: The checks for @ here are just to avoid misinterpreting
 					// the module cache directories (formerly GOPATH/src/mod/foo@v1.5.2/bar).
 					// It's not strictly necessary but helpful to keep the checks.
 					if modRoot != "" && dir == modRoot {
-						pkg = Target.Path
+						pkg = targetPrefix
 					} else if modRoot != "" && strings.HasPrefix(dir, modRoot+string(filepath.Separator)) && !strings.Contains(dir[len(modRoot):], "@") {
 						suffix := filepath.ToSlash(dir[len(modRoot):])
 						if strings.HasPrefix(suffix, "/vendor/") {
@@ -121,7 +141,13 @@ func ImportPathsQuiet(patterns []string, tags map[string]bool) []*search.Match {
 								continue
 							}
 						} else {
-							pkg = Target.Path + suffix
+							modPkg := targetPrefix + suffix
+							if _, ok := dirInModule(modPkg, targetPrefix, modRoot, true); ok {
+								pkg = modPkg
+							} else if !iterating {
+								ModRoot()
+								base.Errorf("go: directory %s is outside main module", base.ShortPath(dir))
+							}
 						}
 					} else if sub := search.InDir(dir, cfg.GOROOTsrc); sub != "" && sub != "." && !strings.Contains(sub, "@") {
 						pkg = filepath.ToSlash(sub)
@@ -134,16 +160,6 @@ func ImportPathsQuiet(patterns []string, tags map[string]bool) []*search.Match {
 							base.Errorf("go: directory %s outside available modules", base.ShortPath(dir))
 						}
 					}
-					info, err := os.Stat(dir)
-					if err != nil || !info.IsDir() {
-						// If the directory is local but does not exist, don't return it
-						// while loader is iterating, since this would trigger a fetch.
-						// After loader is done iterating, we still need to return the
-						// path, so that "go list -e" produces valid output.
-						if iterating {
-							continue
-						}
-					}
 					m.Pkgs = append(m.Pkgs, pkg)
 				}
 
@@ -247,14 +263,30 @@ func pathInModuleCache(dir string) string {
 	return ""
 }
 
-// warnPattern returns list, the result of matching pattern,
-// but if list is empty then first it prints a warning about
-// the pattern not matching any packages.
-func warnPattern(pattern string, list []string) []string {
-	if len(list) == 0 {
-		fmt.Fprintf(os.Stderr, "warning: %q matched no packages\n", pattern)
+var dirContainsPackageCache sync.Map // absolute dir → bool
+
+func dirContainsPackage(dir string) bool {
+	isPkg, ok := dirContainsPackageCache.Load(dir)
+	if !ok {
+		_, err := cfg.BuildContext.ImportDir(dir, 0)
+		if err == nil {
+			isPkg = true
+		} else {
+			if fi, statErr := os.Stat(dir); statErr != nil || !fi.IsDir() {
+				// A non-directory or inaccessible directory is not a Go package.
+				isPkg = false
+			} else if _, noGo := err.(*build.NoGoError); noGo {
+				// A directory containing no Go source files is not a Go package.
+				isPkg = false
+			} else {
+				// An error other than *build.NoGoError indicates that the package exists
+				// but has some other problem (such as a syntax error).
+				isPkg = true
+			}
+		}
+		isPkg, _ = dirContainsPackageCache.LoadOrStore(dir, isPkg)
 	}
-	return list
+	return isPkg.(bool)
 }
 
 // ImportFromFiles adds modules to the build list as needed
@@ -355,11 +387,13 @@ func loadAll(testAll bool) []string {
 
 	var paths []string
 	for _, pkg := range loaded.pkgs {
-		if e, ok := pkg.err.(*ImportMissingError); ok && e.Module.Path == "" {
-			continue // Package doesn't actually exist.
+		if pkg.err != nil {
+			base.Errorf("%s: %v", pkg.stackText(), pkg.err)
+			continue
 		}
 		paths = append(paths, pkg.path)
 	}
+	base.ExitIfErrors()
 	return paths
 }
 
@@ -1108,7 +1142,9 @@ func (r *mvsReqs) required(mod module.Version) ([]module.Version, error) {
 		return nil, module.VersionError(mod, errors.New("parsing go.mod: missing module line"))
 	}
 	if mpath := f.Module.Mod.Path; mpath != origPath && mpath != mod.Path {
-		return nil, module.VersionError(mod, fmt.Errorf("parsing go.mod: unexpected module path %q", mpath))
+		return nil, module.VersionError(mod, fmt.Errorf(`parsing go.mod:
+	module declares its path as: %s
+	        but was required as: %s`, mpath, mod.Path))
 	}
 	if f.Go != nil {
 		r.versions.LoadOrStore(mod, f.Go.Version)

libgo/go/cmd/go/internal/modload/query.go

@@ -28,9 +28,10 @@ import (
 //   tagged version, with non-prereleases preferred over prereleases.
 //   If there are no tagged versions in the repo, latest returns the most
 //   recent commit.
+// - the literal string "upgrade", equivalent to "latest" except that if
+//   current is a newer version, current will be returned (see below).
 // - the literal string "patch", denoting the latest available tagged version
-//   with the same major and minor number as current. If current is "",
-//   "patch" is equivalent to "latest".
+//   with the same major and minor number as current (see below).
 // - v1, denoting the latest available tagged version v1.x.x.
 // - v1.2, denoting the latest available tagged version v1.2.x.
 // - v1.2.3, a semantic version string denoting that tagged version.
@@ -39,11 +40,12 @@ import (
 //   with non-prereleases preferred over prereleases.
 // - a repository commit identifier or tag, denoting that commit.
 //
-// current is optional, denoting the current version of the module.
-// If query is "latest" or "patch", current will be returned if it is a newer
-// semantic version or if it is a chronologically later pseudoversion. This
-// prevents accidental downgrades from newer prerelease or development
-// versions.
+// current denotes the current version of the module; it may be "" if the
+// current version is unknown or should not be considered. If query is
+// "upgrade" or "patch", current will be returned if it is a newer
+// semantic version or a chronologically later pseudo-version than the
+// version that would otherwise be chosen. This prevents accidental downgrades
+// from newer pre-release or development versions.
 //
 // If the allowed function is non-nil, Query excludes any versions for which
 // allowed returns false.
@@ -81,6 +83,10 @@ func queryProxy(proxy, path, query, current string, allowed func(module.Version)
 		ok = allowed
 		mayUseLatest = true
 
+	case query == "upgrade":
+		ok = allowed
+		mayUseLatest = true
+
 	case query == "patch":
 		if current == "" {
 			ok = allowed
@@ -202,9 +208,9 @@ func queryProxy(proxy, path, query, current string, allowed func(module.Version)
 			return nil, err
 		}
 
-		// For "latest" and "patch", make sure we don't accidentally downgrade
+		// For "upgrade" and "patch", make sure we don't accidentally downgrade
 		// from a newer prerelease or from a chronologically newer pseudoversion.
-		if current != "" && (query == "latest" || query == "patch") {
+		if current != "" && (query == "upgrade" || query == "patch") {
 			currentTime, err := modfetch.PseudoVersionTime(current)
 			if semver.Compare(rev.Version, current) < 0 || (err == nil && rev.Time.Before(currentTime)) {
 				return repo.Stat(current)
@@ -374,10 +380,10 @@ func QueryPattern(pattern, query string, allowed func(module.Version) bool) ([]Q
 			}
 			r.Packages = match(r.Mod, root, isLocal)
 			if len(r.Packages) == 0 {
-				return r, &packageNotInModuleError{
-					mod:     r.Mod,
-					query:   query,
-					pattern: pattern,
+				return r, &PackageNotInModuleError{
+					Mod:     r.Mod,
+					Query:   query,
+					Pattern: pattern,
 				}
 			}
 			return r, nil
@@ -440,30 +446,31 @@ func queryPrefixModules(candidateModules []string, queryModule func(path string)
 	wg.Wait()
 
 	// Classify the results. In case of failure, identify the error that the user
-	// is most likely to find helpful.
+	// is most likely to find helpful: the most useful class of error at the
+	// longest matching path.
 	var (
+		noPackage   *PackageNotInModuleError
 		noVersion   *NoMatchingVersionError
-		noPackage   *packageNotInModuleError
 		notExistErr error
 	)
 	for _, r := range results {
 		switch rErr := r.err.(type) {
 		case nil:
 			found = append(found, r.QueryResult)
+		case *PackageNotInModuleError:
+			if noPackage == nil {
+				noPackage = rErr
+			}
 		case *NoMatchingVersionError:
 			if noVersion == nil {
 				noVersion = rErr
 			}
-		case *packageNotInModuleError:
-			if noPackage == nil {
-				noPackage = rErr
-			}
 		default:
 			if errors.Is(rErr, os.ErrNotExist) {
 				if notExistErr == nil {
 					notExistErr = rErr
 				}
-			} else {
+			} else if err == nil {
 				err = r.err
 			}
 		}
@@ -503,37 +510,37 @@ type NoMatchingVersionError struct {
 
 func (e *NoMatchingVersionError) Error() string {
 	currentSuffix := ""
-	if (e.query == "latest" || e.query == "patch") && e.current != "" {
+	if (e.query == "upgrade" || e.query == "patch") && e.current != "" {
 		currentSuffix = fmt.Sprintf(" (current version is %s)", e.current)
 	}
 	return fmt.Sprintf("no matching versions for query %q", e.query) + currentSuffix
 }
 
-// A packageNotInModuleError indicates that QueryPattern found a candidate
+// A PackageNotInModuleError indicates that QueryPattern found a candidate
 // module at the requested version, but that module did not contain any packages
 // matching the requested pattern.
 //
-// NOTE: packageNotInModuleError MUST NOT implement Is(os.ErrNotExist).
+// NOTE: PackageNotInModuleError MUST NOT implement Is(os.ErrNotExist).
 //
 // If the module came from a proxy, that proxy had to return a successful status
 // code for the versions it knows about, and thus did not have the opportunity
 // to return a non-400 status code to suppress fallback.
-type packageNotInModuleError struct {
-	mod     module.Version
-	query   string
-	pattern string
+type PackageNotInModuleError struct {
+	Mod     module.Version
+	Query   string
+	Pattern string
 }
 
-func (e *packageNotInModuleError) Error() string {
+func (e *PackageNotInModuleError) Error() string {
 	found := ""
-	if e.query != e.mod.Version {
-		found = fmt.Sprintf(" (%s)", e.mod.Version)
+	if e.Query != e.Mod.Version {
+		found = fmt.Sprintf(" (%s)", e.Mod.Version)
 	}
 
-	if strings.Contains(e.pattern, "...") {
-		return fmt.Sprintf("module %s@%s%s found, but does not contain packages matching %s", e.mod.Path, e.query, found, e.pattern)
+	if strings.Contains(e.Pattern, "...") {
+		return fmt.Sprintf("module %s@%s%s found, but does not contain packages matching %s", e.Mod.Path, e.Query, found, e.Pattern)
 	}
-	return fmt.Sprintf("module %s@%s%s found, but does not contain package %s", e.mod.Path, e.query, found, e.pattern)
+	return fmt.Sprintf("module %s@%s%s found, but does not contain package %s", e.Mod.Path, e.Query, found, e.Pattern)
 }
 
 // ModuleHasRootPackage returns whether module m contains a package m.Path.

libgo/go/cmd/go/internal/modload/query_test.go

@@ -100,7 +100,7 @@ var queryTests = []struct {
 	{path: queryRepo, query: ">=v0.0.0", vers: "v0.0.0"},
 	{path: queryRepo, query: "v0.0.1", vers: "v0.0.1"},
 	{path: queryRepo, query: "v0.0.1+foo", vers: "v0.0.1"},
-	{path: queryRepo, query: "v0.0.99", err: `unknown revision v0.0.99`},
+	{path: queryRepo, query: "v0.0.99", err: `vcs-test.golang.org/git/querytest.git@v0.0.99: invalid version: unknown revision v0.0.99`},
 	{path: queryRepo, query: "v0", vers: "v0.3.0"},
 	{path: queryRepo, query: "v0.1", vers: "v0.1.2"},
 	{path: queryRepo, query: "v0.2", err: `no matching versions for query "v0.2"`},
@@ -112,15 +112,17 @@ var queryTests = []struct {
 	// unconditionally).
 	{path: queryRepo, query: "42abcb6df8ee", vers: "v1.9.10-pre2.0.20190513201126-42abcb6df8ee"},
 
-	{path: queryRepo, query: "v1.9.10-pre2+wrongmetadata", err: `unknown revision v1.9.10-pre2+wrongmetadata`},
-	{path: queryRepo, query: "v1.9.10-pre2", err: `unknown revision v1.9.10-pre2`},
+	{path: queryRepo, query: "v1.9.10-pre2+wrongmetadata", err: `vcs-test.golang.org/git/querytest.git@v1.9.10-pre2+wrongmetadata: invalid version: unknown revision v1.9.10-pre2+wrongmetadata`},
+	{path: queryRepo, query: "v1.9.10-pre2", err: `vcs-test.golang.org/git/querytest.git@v1.9.10-pre2: invalid version: unknown revision v1.9.10-pre2`},
 	{path: queryRepo, query: "latest", vers: "v1.9.9"},
-	{path: queryRepo, query: "latest", current: "v1.9.10-pre1", vers: "v1.9.10-pre1"},
-	{path: queryRepo, query: "latest", current: "v1.9.10-pre2+metadata", vers: "v1.9.10-pre2.0.20190513201126-42abcb6df8ee"},
-	{path: queryRepo, query: "latest", current: "v0.0.0-20190513201126-42abcb6df8ee", vers: "v0.0.0-20190513201126-42abcb6df8ee"},
-	{path: queryRepo, query: "latest", allow: "NOMATCH", err: `no matching versions for query "latest"`},
-	{path: queryRepo, query: "latest", current: "v1.9.9", allow: "NOMATCH", err: `no matching versions for query "latest" (current version is v1.9.9)`},
-	{path: queryRepo, query: "latest", current: "v1.99.99", err: `unknown revision v1.99.99`},
+	{path: queryRepo, query: "latest", current: "v1.9.10-pre1", vers: "v1.9.9"},
+	{path: queryRepo, query: "upgrade", vers: "v1.9.9"},
+	{path: queryRepo, query: "upgrade", current: "v1.9.10-pre1", vers: "v1.9.10-pre1"},
+	{path: queryRepo, query: "upgrade", current: "v1.9.10-pre2+metadata", vers: "v1.9.10-pre2.0.20190513201126-42abcb6df8ee"},
+	{path: queryRepo, query: "upgrade", current: "v0.0.0-20190513201126-42abcb6df8ee", vers: "v0.0.0-20190513201126-42abcb6df8ee"},
+	{path: queryRepo, query: "upgrade", allow: "NOMATCH", err: `no matching versions for query "upgrade"`},
+	{path: queryRepo, query: "upgrade", current: "v1.9.9", allow: "NOMATCH", err: `no matching versions for query "upgrade" (current version is v1.9.9)`},
+	{path: queryRepo, query: "upgrade", current: "v1.99.99", err: `vcs-test.golang.org/git/querytest.git@v1.99.99: invalid version: unknown revision v1.99.99`},
 	{path: queryRepo, query: "patch", current: "", vers: "v1.9.9"},
 	{path: queryRepo, query: "patch", current: "v0.1.0", vers: "v0.1.2"},
 	{path: queryRepo, query: "patch", current: "v1.9.0", vers: "v1.9.9"},
@@ -159,8 +161,11 @@ var queryTests = []struct {
 	{path: queryRepoV2, query: "v2.6.0-pre1", vers: "v2.6.0-pre1"},
 	{path: queryRepoV2, query: "latest", vers: "v2.5.5"},
 
-	{path: queryRepoV3, query: "e0cf3de987e6", vers: "v3.0.0-20180704024501-e0cf3de987e6"},
-	{path: queryRepoV3, query: "latest", vers: "v3.0.0-20180704024501-e0cf3de987e6"},
+	// e0cf3de987e6 is the latest commit on the master branch, and it's actually
+	// v1.19.10-pre1, not anything resembling v3: attempting to query it as such
+	// should fail.
+	{path: queryRepoV3, query: "e0cf3de987e6", err: `vcs-test.golang.org/git/querytest.git/v3@v3.0.0-20180704024501-e0cf3de987e6: invalid version: go.mod has non-.../v3 module path "vcs-test.golang.org/git/querytest.git" (and .../v3/go.mod does not exist) at revision e0cf3de987e6`},
+	{path: queryRepoV3, query: "latest", err: `no matching versions for query "latest"`},
 
 	{path: emptyRepo, query: "latest", vers: "v0.0.0-20180704023549-7bb914627242"},
 	{path: emptyRepo, query: ">v0.0.0", err: `no matching versions for query ">v0.0.0"`},
@@ -180,7 +185,10 @@ func TestQuery(t *testing.T) {
 			ok, _ := path.Match(allow, m.Version)
 			return ok
 		}
+		tt := tt
 		t.Run(strings.ReplaceAll(tt.path, "/", "_")+"/"+tt.query+"/"+tt.current+"/"+allow, func(t *testing.T) {
+			t.Parallel()
+
 			info, err := Query(tt.path, tt.query, tt.current, allowed)
 			if tt.err != "" {
 				if err == nil {

libgo/go/cmd/go/internal/mvs/mvs.go

@@ -216,8 +216,8 @@ func buildList(target module.Version, reqs Reqs, upgrade func(module.Version) (m
 		}
 	}
 
-	// Construct the list by traversing the graph again, replacing older
-	// modules with required minimum versions.
+	// The final list is the minimum version of each module found in the graph.
+
 	if v := min[target.Path]; v != target.Version {
 		// TODO(jayconrod): there is a special case in modload.mvsReqs.Max
 		// that prevents us from selecting a newer version of a module
@@ -228,19 +228,18 @@ func buildList(target module.Version, reqs Reqs, upgrade func(module.Version) (m
 	}
 
 	list := []module.Version{target}
-	listed := map[string]bool{target.Path: true}
-	for i := 0; i < len(list); i++ {
-		n := modGraph[list[i]]
+	for path, vers := range min {
+		if path != target.Path {
+			list = append(list, module.Version{Path: path, Version: vers})
+		}
+
+		n := modGraph[module.Version{Path: path, Version: vers}]
 		required := n.required
 		for _, r := range required {
 			v := min[r.Path]
 			if r.Path != target.Path && reqs.Max(v, r.Version) != v {
 				panic(fmt.Sprintf("mistake: version %q does not satisfy requirement %+v", v, r)) // TODO: Don't panic.
 			}
-			if !listed[r.Path] {
-				list = append(list, module.Version{Path: r.Path, Version: v})
-				listed[r.Path] = true
-			}
 		}
 	}
 
@@ -289,12 +288,12 @@ func Req(target module.Version, list []module.Version, base []string, reqs Reqs)
 	}
 
 	// Walk modules in reverse post-order, only adding those not implied already.
-	have := map[string]string{}
+	have := map[module.Version]bool{}
 	walk = func(m module.Version) error {
-		if v, ok := have[m.Path]; ok && reqs.Max(m.Version, v) == v {
+		if have[m] {
 			return nil
 		}
-		have[m.Path] = m.Version
+		have[m] = true
 		for _, m1 := range reqCache[m] {
 			walk(m1)
 		}
@@ -322,7 +321,7 @@ func Req(target module.Version, list []module.Version, base []string, reqs Reqs)
 			// Older version.
 			continue
 		}
-		if have[m.Path] != m.Version {
+		if !have[m] {
 			min = append(min, m)
 			walk(m)
 		}

libgo/go/cmd/go/internal/mvs/mvs_test.go

@@ -29,7 +29,7 @@ D5: E2
 G1: C4
 A2: B1 C4 D4
 build A: A B1 C2 D4 E2 F1
-upgrade* A: A B1 C4 D5 E2 G1
+upgrade* A: A B1 C4 D5 E2 F1 G1
 upgrade A C4: A B1 C4 D4 E2 F1 G1
 downgrade A2 D2: A2 C4 D2
 
@@ -38,7 +38,7 @@ A: B1 C2
 B1: D3
 C2: B2
 B2:
-build A: A B2 C2
+build A: A B2 C2 D3
 
 # Cross-dependency between D and E.
 # No matter how it arises, should get result of merging all build lists via max,
@@ -157,7 +157,18 @@ D1: E2
 E1: D2
 build A: A B C D2 E2
 
-# Upgrade from B1 to B2 should drop the transitive dep on D.
+# golang.org/issue/31248:
+# Even though we select X2, the requirement on I1
+# via X1 should be preserved.
+name: cross8
+M: A1 B1
+A1: X1
+B1: X2
+X1: I1
+X2: 
+build M: M A1 B1 I1 X2
+
+# Upgrade from B1 to B2 should not drop the transitive dep on D.
 name: drop
 A: B1 C1
 B1: D1
@@ -165,14 +176,14 @@ B2:
 C2:
 D2:
 build A: A B1 C1 D1
-upgrade* A: A B2 C2
+upgrade* A: A B2 C2 D2
 
 name: simplify
 A: B1 C1
 B1: C2
 C1: D1
 C2:
-build A: A B1 C2
+build A: A B1 C2 D1
 
 name: up1
 A: B1 C1
@@ -254,8 +265,9 @@ build A: A B1
 upgrade A B2: A B2
 upgrade* A: A B3
 
+# golang.org/issue/29773:
 # Requirements of older versions of the target
-# must not be carried over.
+# must be carried over.
 name: cycle2
 A: B1
 A1: C1
@@ -265,8 +277,8 @@ B2: A2
 C1: A2
 C2:
 D2:
-build A: A B1
-upgrade* A: A B2
+build A: A B1 C1 D1
+upgrade* A: A B2 C2 D2
 
 # Requirement minimization.
 
@@ -283,6 +295,14 @@ H1: G1
 req A: G1
 req A G: G1
 req A H: H1
+
+name: req3
+M: A1 B1
+A1: X1
+B1: X2
+X1: I1
+X2: 
+req M: A1 B1
 `
 
 func Test(t *testing.T) {

libgo/go/cmd/go/internal/test/test.go

@@ -843,7 +843,7 @@ func builderTest(b *work.Builder, p *load.Package) (buildAction, runAction, prin
 	if !cfg.BuildN {
 		// writeTestmain writes _testmain.go,
 		// using the test description gathered in t.
-		if err := ioutil.WriteFile(testDir+"_testmain.go", pmain.Internal.TestmainGo, 0666); err != nil {
+		if err := ioutil.WriteFile(testDir+"_testmain.go", *pmain.Internal.TestmainGo, 0666); err != nil {
 			return nil, nil, nil, err
 		}
 	}
@@ -1250,6 +1250,15 @@ func (c *runCache) tryCacheWithID(b *work.Builder, a *work.Action, id string) bo
 		return false
 	}
 
+	if a.Package.Root == "" {
+		// Caching does not apply to tests outside of any module, GOPATH, or GOROOT.
+		if cache.DebugTest {
+			fmt.Fprintf(os.Stderr, "testcache: caching disabled for package outside of module root, GOPATH, or GOROOT: %s\n", a.Package.ImportPath)
+		}
+		c.disableCache = true
+		return false
+	}
+
 	var cacheArgs []string
 	for _, arg := range testArgs {
 		i := strings.Index(arg, "=")
@@ -1437,8 +1446,8 @@ func computeTestInputsID(a *work.Action, testlog []byte) (cache.ActionID, error)
 			if !filepath.IsAbs(name) {
 				name = filepath.Join(pwd, name)
 			}
-			if !inDir(name, a.Package.Root) {
-				// Do not recheck files outside the GOPATH or GOROOT root.
+			if a.Package.Root == "" || !inDir(name, a.Package.Root) {
+				// Do not recheck files outside the module, GOPATH, or GOROOT root.
 				break
 			}
 			fmt.Fprintf(h, "stat %s %x\n", name, hashStat(name))
@@ -1446,8 +1455,8 @@ func computeTestInputsID(a *work.Action, testlog []byte) (cache.ActionID, error)
 			if !filepath.IsAbs(name) {
 				name = filepath.Join(pwd, name)
 			}
-			if !inDir(name, a.Package.Root) {
-				// Do not recheck files outside the GOPATH or GOROOT root.
+			if a.Package.Root == "" || !inDir(name, a.Package.Root) {
+				// Do not recheck files outside the module, GOPATH, or GOROOT root.
 				break
 			}
 			fh, err := hashOpen(name)

libgo/go/cmd/go/internal/version/exe.go

@@ -103,6 +103,11 @@ func (x *elfExe) ReadData(addr, size uint64) ([]byte, error) {
 }
 
 func (x *elfExe) DataStart() uint64 {
+	for _, s := range x.f.Sections {
+		if s.Name == ".go.buildinfo" {
+			return s.Addr
+		}
+	}
 	for _, p := range x.f.Progs {
 		if p.Type == elf.PT_LOAD && p.Flags&(elf.PF_X|elf.PF_W) == elf.PF_W {
 			return p.Vaddr
@@ -208,7 +213,13 @@ func (x *machoExe) ReadData(addr, size uint64) ([]byte, error) {
 }
 
 func (x *machoExe) DataStart() uint64 {
-	// Assume data is first non-empty writable segment.
+	// Look for section named "__go_buildinfo".
+	for _, sec := range x.f.Sections {
+		if sec.Name == "__go_buildinfo" {
+			return sec.Addr
+		}
+	}
+	// Try the first non-empty writable segment.
 	const RW = 3
 	for _, load := range x.f.Loads {
 		seg, ok := load.(*macho.Segment)

libgo/go/cmd/go/internal/work/build.go

@@ -30,6 +30,8 @@ along with their dependencies, but it does not install the results.
 If the arguments to build are a list of .go files from a single directory,
 build treats them as a list of source files specifying a single package.
 
+When compiling packages, build ignores files that end in '_test.go'.
+
 When compiling a single main package, build writes
 the resulting executable to an output file named after
 the first source file ('go build ed.go rx.go' writes 'ed' or 'ed.exe')
@@ -40,8 +42,6 @@ When compiling multiple packages or a single non-main package,
 build compiles the packages but discards the resulting object,
 serving only as a check that the packages can be built.
 
-When compiling packages, build ignores files that end in '_test.go'.
-
 The -o flag forces build to write the resulting executable or object
 to the named output file or directory, instead of the default behavior described
 in the last two paragraphs. If the named output is a directory that exists,

libgo/go/cmd/go/internal/work/buildid.go

@@ -203,8 +203,9 @@ func (b *Builder) toolID(name string) string {
 		// On the development branch, use the content ID part of the build ID.
 		id = contentID(f[len(f)-1])
 	} else {
-		// For a release, the output is like: "compile version go1.9.1". Use the whole line.
-		id = f[2]
+		// For a release, the output is like: "compile version go1.9.1 X:framepointer".
+		// Use the whole line.
+		id = strings.TrimSpace(line)
 	}
 
 	b.id.Lock()

libgo/go/cmd/go/internal/work/exec.go

@@ -542,15 +542,6 @@ func (b *Builder) build(a *Action) (err error) {
 		}
 	}
 
-	// Write out the _testinginit.go file for any test packages that import "testing".
-	if a.Package.Internal.TestinginitGo != nil {
-		initfile := objdir + "_testinginit.go"
-		if err := b.writeFile(initfile, a.Package.Internal.TestinginitGo); err != nil {
-			return err
-		}
-		gofiles = append([]string{initfile}, gofiles...)
-	}
-
 	// Run cgo.
 	if a.Package.UsesCgo() || a.Package.UsesSwig() {
 		// In a package using cgo, cgo compiles the C, C++ and assembly files with gcc.

libgo/go/cmd/go/testdata/flag_test.go

-// Copyright 2019 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 flag_test
 
 import (
 	"flag"
+	"log"
 	"testing"
 )
 
 var v = flag.Int("v", 0, "v flag")
 
-// Run this as go test pkg -args -v=7
+// Run this as go test pkg -v=7
 func TestVFlagIsSet(t *testing.T) {
 	if *v != 7 {
-		t.Fatal("v flag not set")
+		log.Fatal("v flag not set")
 	}
 }

libgo/go/cmd/go/testdata/mod/example.com_badchain_c_v1.1.0.txt

 example.com/badchain/c v1.1.0
 
 -- .mod --
-module example.com/badchain/wrong
+module badchain.example.com/c
 -- .info --
 {"Version":"v1.1.0"}
 -- c.go --

libgo/go/cmd/go/testdata/script/build_cache_output.txt

 env GO111MODULE=off
+env GODEBUG=gocachetest=1
 
 [!gc] skip
 [short] skip # clears cache, rebuilds too much
@@ -32,7 +33,7 @@ stderr 'main.go:2.* can inline main' # from compiler
 stderr '\d+ symbols' # from linker
 
 # Running a test should run the compiler, linker, and the test the first time.
-go test -v -x -gcflags=-m -ldflags=-v p_test.go
+go test -v -x -gcflags=-m -ldflags=-v p
 stderr 'compile( |\.exe"?)'
 stderr 'p_test.go:.*can inline Test' # from compile of p_test
 stderr 'testmain\.go:.*inlin' # from compile of testmain
@@ -42,7 +43,7 @@ stderr 'p\.test( |\.exe"?)'
 stdout 'TEST' # from test
 
 # ... but not the second, even though it still prints the compiler, linker, and test output.
-go test -v -x -gcflags=-m -ldflags=-v p_test.go
+go test -v -x -gcflags=-m -ldflags=-v p
 ! stderr 'compile( |\.exe"?)'
 stderr 'p_test.go:.*can inline Test' # from compile of p_test
 stderr 'testmain\.go:.*inlin' # from compile of testmain
@@ -60,7 +61,7 @@ func f(x *int) *int { return x }
 package main
 func main() {}
 
--- p_test.go --
+-- p/p_test.go --
 package p
 import "testing"
 func Test(t *testing.T) {println("TEST")}

libgo/go/cmd/go/testdata/script/cmd_import_error.txt

+env GO111MODULE=on
+
+# Regression test for golang.org/issue/31031:
+# Importing or loading a non-existent package in cmd/ should print
+# a clear error in module mode.
+
+! go list cmd/unknown
+stderr '^can''t load package: package cmd/unknown: package cmd/unknown is not in GOROOT \('$GOROOT'[/\\]src[/\\]cmd[/\\]unknown\)$'
+
+go list -f '{{range .DepsErrors}}{{.Err}}{{end}}' x.go
+stdout '^package cmd/unknown is not in GOROOT \('$GOROOT'[/\\]src[/\\]cmd[/\\]unknown\)$'
+
+-- x.go --
+package x
+
+import _ "cmd/unknown"

libgo/go/cmd/go/testdata/script/mod_doc.txt

@@ -3,6 +3,7 @@
 env GO111MODULE=on
 [short] skip
 
+# Check when module x is inside GOPATH/src.
 go doc y
 stdout 'Package y is.*alphabet'
 stdout 'import "x/y"'
@@ -16,13 +17,25 @@ stdout 'Hello returns a greeting'
 go doc quote
 stdout 'Package quote collects pithy sayings.'
 
-# Double-check go doc y when y is not in GOPATH/src.
-env GOPATH=$WORK/altgopath
+# Double-check when module x is outside GOPATH/src.
+env GOPATH=$WORK/emptygopath
 go doc x/y
 stdout 'Package y is.*alphabet'
 go doc y
 stdout 'Package y is.*alphabet'
 
+# Triple-check when module x is outside GOPATH/src,
+# but other packages with same import paths are in GOPATH/src.
+# Since go doc is running in module mode here, packages in active module
+# should be preferred over packages in GOPATH. See golang.org/issue/28992.
+env GOPATH=$WORK/gopath2
+go doc x/y
+! stdout 'Package y is.*GOPATH'
+stdout 'Package y is.*alphabet'
+go doc rsc.io/quote
+! stdout 'Package quote is located in a GOPATH workspace.'
+stdout 'Package quote collects pithy sayings.'
+
 -- go.mod --
 module x
 require rsc.io/quote v1.5.2
@@ -33,3 +46,13 @@ package y
 
 -- x.go --
 package x
+
+-- $WORK/gopath2/src/x/y/y.go --
+// Package y is located in a GOPATH workspace.
+package y
+-- $WORK/gopath2/src/rsc.io/quote/quote.go --
+// Package quote is located in a GOPATH workspace.
+package quote
+
+// Hello is located in a GOPATH workspace.
+func Hello() string { return "" }

libgo/go/cmd/go/testdata/script/mod_dot.txt

+env GO111MODULE=on
+
+# golang.org/issue/32917 and golang.org/issue/28459: 'go build' and 'go test'
+# in an empty directory should refer to the path '.' and should not attempt
+# to resolve an external module.
+cd dir
+! go get .
+stderr 'go get \.: path .* is not a package in module rooted at .*[/\\]dir$'
+! go list
+! stderr 'cannot find module providing package'
+stderr '^can.t load package: package \.: no Go files in '$WORK'[/\\]gopath[/\\]src[/\\]dir$'
+
+cd subdir
+! go list
+! stderr 'cannot find module providing package'
+stderr '^can.t load package: package \.: no Go files in '$WORK'[/\\]gopath[/\\]src[/\\]dir[/\\]subdir$'
+cd ..
+
+# golang.org/issue/30590: if a package is found in the filesystem
+# but is not in the main module, the error message should not say
+# "cannot find module providing package", and we shouldn't try
+# to find a module providing the package.
+! go list ./othermodule
+! stderr 'cannot find module providing package'
+stderr 'go: directory othermodule is outside main module'
+
+-- dir/go.mod --
+module example.com
+go 1.13
+-- dir/subdir/README --
+There are no Go source files in this directory.
+-- dir/othermodule/go.mod --
+module example.com/othermodule
+go 1.13
+-- dir/othermodule/om.go --
+package othermodule

libgo/go/cmd/go/testdata/script/mod_download.txt

@@ -17,6 +17,7 @@ stderr 'this.domain.is.invalid'
 stdout '"Error": ".*this.domain.is.invalid.*"'
 
 # download -json with version should print JSON
+# and download the .info file for the 'latest' version.
 go mod download -json 'rsc.io/quote@<=v1.5.0'
 stdout '^\t"Path": "rsc.io/quote"'
 stdout '^\t"Version": "v1.5.0"'
@@ -27,13 +28,14 @@ stdout '^\t"Sum": "h1:6fJa6E\+wGadANKkUMlZ0DhXFpoKlslOQDCo259XtdIE="'  # hash of
 stdout '^\t"GoModSum": "h1:LzX7hefJvL54yjefDEDHNONDjII0t9xZLPXsUe\+TKr0="'
 ! stdout '"Error"'
 
+exists $GOPATH/pkg/mod/cache/download/rsc.io/quote/@v/v1.5.2.info
+
 # download queries above should not have added to go.mod.
 go list -m all
 ! stdout rsc.io
 
 # add to go.mod so we can test non-query downloads
 go mod edit -require rsc.io/quote@v1.5.2
-! exists $GOPATH/pkg/mod/cache/download/rsc.io/quote/@v/v1.5.2.info
 ! exists $GOPATH/pkg/mod/cache/download/rsc.io/quote/@v/v1.5.2.mod
 ! exists $GOPATH/pkg/mod/cache/download/rsc.io/quote/@v/v1.5.2.zip
 
@@ -83,6 +85,16 @@ exists $GOPATH/pkg/mod/cache/download/rsc.io/quote/@v/v1.5.3-pre1.zip
 go mod download -json rsc.io/quote@v1.5.1
 exists $GOPATH/pkg/mod/cache/download/rsc.io/quote/@v/v1.5.1.zip
 
+# download reports errors encountered when locating modules
+! go mod download bad/path
+stderr '^module bad/path: not a known dependency$'
+! go mod download bad/path@latest
+stderr '^bad/path@latest: malformed module path "bad/path": missing dot in first path element$'
+! go mod download rsc.io/quote@v1.999.999
+stderr '^rsc.io/quote@v1.999.999: reading .*/v1.999.999.info: 404 Not Found$'
+! go mod download -json bad/path
+stdout '^\t"Error": "module bad/path: not a known dependency"'
+
 # allow go mod download without go.mod
 env GO111MODULE=auto
 rm go.mod

libgo/go/cmd/go/testdata/script/mod_download_latest.txt

+env GO111MODULE=on
+
+# If the module is the latest version of itself,
+# the Latest field should be set.
+go mod download -json rsc.io/quote@v1.5.2
+stdout '"Latest":\s*true'
+
+# If the module is older than latest, the field should be unset.
+go mod download -json rsc.io/quote@v1.5.1
+! stdout '"Latest":'
+
+# If the module is newer than "latest", the field should be unset...
+go mod download -json rsc.io/quote@v1.5.3-pre1
+! stdout '"Latest":'
+
+# ...even if that version is also what is required by the main module.
+go mod init example.com
+go mod edit -require rsc.io/quote@v1.5.3-pre1
+go mod download -json rsc.io/quote@v1.5.3-pre1
+! stdout '"Latest":'

libgo/go/cmd/go/testdata/script/mod_fs_patterns.txt

@@ -34,11 +34,11 @@ stderr 'import lookup disabled'
 
 ! go build -mod=readonly ./nonexist
 ! stderr 'import lookup disabled'
-stderr 'unknown import path "m/nonexist": cannot find package'
+stderr '^can.t load package: package ./nonexist: cannot find package "." in:\n\t'$WORK'[/\\]gopath[/\\]src[/\\]x[/\\]nonexist$'
 
 ! go build -mod=readonly ./go.mod
 ! stderr 'import lookup disabled'
-stderr 'unknown import path "m/go.mod": cannot find package'
+stderr 'can.t load package: package ./go.mod: cannot find package'
 
 -- x/go.mod --
 module m

libgo/go/cmd/go/testdata/script/mod_get_fallback.txt

+env GO111MODULE=on
+
+[!net] skip
+
+env GOPROXY=https://proxy.golang.org,direct
+env GOSUMDB=off
+
+go get -x -v -d golang.org/x/tools/cmd/goimports
+stderr '# get https://proxy.golang.org/golang.org/x/tools/@latest'
+! stderr '# get https://golang.org'

libgo/go/cmd/go/testdata/script/mod_get_main.txt

@@ -4,13 +4,19 @@ env GO111MODULE=on
 # @patch and @latest within the main module refer to the current version.
 # The main module won't be upgraded, but missing dependencies will be added.
 cp go.mod.orig go.mod
-go get -d rsc.io/x@latest
+go get -d rsc.io/x
+grep 'rsc.io/quote v1.5.2' go.mod
+go get -d rsc.io/x@upgrade
 grep 'rsc.io/quote v1.5.2' go.mod
 cp go.mod.orig go.mod
 go get -d rsc.io/x@patch
 grep 'rsc.io/quote v1.5.2' go.mod
 cp go.mod.orig go.mod
 
+# The main module cannot be updated to @latest, which is a specific version.
+! go get -d rsc.io/x@latest
+stderr '^go get rsc.io/x@latest: can.t request explicit version of path in main module$'
+
 # The main module cannot be updated to a specific version.
 ! go get rsc.io/x@v0.1.0
 stderr '^go get rsc.io/x@v0.1.0: can.t request explicit version of path in main module$'

libgo/go/cmd/go/testdata/script/mod_get_newcycle.txt

 env GO111MODULE=on
 
 # Download modules to avoid stderr chatter
+go mod download example.com@v1.0.0
 go mod download example.com/newcycle/a@v1.0.0
 go mod download example.com/newcycle/a@v1.0.1
 go mod download example.com/newcycle/b@v1.0.0
@@ -10,5 +11,6 @@ go mod init m
 cmp stderr stderr-expected
 
 -- stderr-expected --
+go: finding example.com/newcycle v1.0.0
 go get: inconsistent versions:
 	example.com/newcycle/a@v1.0.0 requires example.com/newcycle/a@v1.0.1 (not example.com/newcycle/a@v1.0.0)

libgo/go/cmd/go/testdata/script/mod_get_patterns.txt

@@ -10,11 +10,11 @@ grep 'require rsc.io/quote' go.mod
 
 cp go.mod.orig go.mod
 ! go get -d rsc.io/quote/x...
-stderr 'go get rsc.io/quote/x...: module rsc.io/quote@latest \(v1.5.2\) found, but does not contain packages matching rsc.io/quote/x...'
+stderr 'go get rsc.io/quote/x...: module rsc.io/quote@upgrade \(v1.5.2\) found, but does not contain packages matching rsc.io/quote/x...'
 ! grep 'require rsc.io/quote' go.mod
 
 ! go get -d rsc.io/quote/x/...
-stderr 'go get rsc.io/quote/x/...: module rsc.io/quote@latest \(v1.5.2\) found, but does not contain packages matching rsc.io/quote/x/...'
+stderr 'go get rsc.io/quote/x/...: module rsc.io/quote@upgrade \(v1.5.2\) found, but does not contain packages matching rsc.io/quote/x/...'
 ! grep 'require rsc.io/quote' go.mod
 
 # If a pattern matches no packages within a module, the module should not

libgo/go/cmd/go/testdata/script/mod_get_svn.txt

@@ -2,19 +2,26 @@
 [!exec:svn] skip
 
 env GO111MODULE=on
-env GOPROXY=direct # obtain llvm.org directory, not via svn.
+env GOPROXY=direct
+env GOSUMDB=off
 
 # Attempting to get a module zip using svn should fail with a reasonable
 # message instead of a panic.
 # TODO(golang.org/issue/26092): Really, it shouldn't fail at all.
-! go get -d llvm.org/llvm/bindings/go/llvm
+! go get -d vcs-test.golang.org/svn/hello.svn
 stderr 'ReadZip not implemented for svn'
 ! go install .
 stderr 'ReadZip not implemented for svn'
 
+# Attempting to get a nonexistent module using svn should fail with a
+# reasonable message instead of a panic.
+! go get -d vcs-test.golang.org/svn/nonexistent.svn
+! stderr panic
+stderr 'go get vcs-test.golang.org/svn/nonexistent.svn: no matching versions for query "upgrade"'
+
 -- go.mod --
 module golang/go/issues/28943/main
 -- main.go --
 package main
-import _ "llvm.org/llvm/bindings/go/llvm"
+import _ "vcs-test.golang.org/svn/hello.svn"
 func main() {}

libgo/go/cmd/go/testdata/script/mod_get_upgrade_pseudo.txt

@@ -9,18 +9,33 @@ env GO111MODULE=on
 # The v0.1.1 pseudo-version is semantically higher than the latest tag.
 # The v0.0.0 pseudo-version is chronologically newer.
 
-# 'get -u' should not downgrade to the (lower) tagged version.
+# Start at v0.1.1-0.20190429073117-b5426c86b553
 go get -d example.com/pseudoupgrade@b5426c8
+go list -m -u all
+stdout '^example.com/pseudoupgrade v0.1.1-0.20190429073117-b5426c86b553$'
+
+# 'get -u' should not downgrade to the (lower) tagged version.
 go get -d -u
 go list -m -u all
 stdout '^example.com/pseudoupgrade v0.1.1-0.20190429073117-b5426c86b553$'
 
-# 'get example.com/pseudoupgrade@latest' should not downgrade to
-# the (lower) tagged version.
-go get -d example.com/pseudoupgrade@latest
+# 'get example.com/pseudoupgrade@upgrade' should not downgrade.
+go get -d example.com/pseudoupgrade@upgrade
 go list -m all
 stdout '^example.com/pseudoupgrade v0.1.1-0.20190429073117-b5426c86b553$'
 
+# 'get example.com/pseudoupgrade' should not downgrade.
+# This is equivalent to 'get example.com/pseudoupgrade@upgrade'.
+go get -d example.com/pseudoupgrade
+go list -m all
+stdout '^example.com/pseudoupgrade v0.1.1-0.20190429073117-b5426c86b553$'
+
+# 'get example.com/pseudoupgrade@latest' should downgrade.
+# @latest should not consider the current version.
+go get -d example.com/pseudoupgrade@latest
+go list -m all
+stdout '^example.com/pseudoupgrade v0.1.0$'
+
 # We should observe the same behavior with the newer pseudo-version.
 go get -d example.com/pseudoupgrade@v0.0.0-20190430073000-30950c05d534
 
@@ -29,12 +44,21 @@ go get -d -u
 go list -m -u all
 stdout '^example.com/pseudoupgrade v0.0.0-20190430073000-30950c05d534$'
 
-# 'get example.com/pseudoupgrade@latest' should not downgrade to the
-# chronologically older tagged version.
-go get -d example.com/pseudoupgrade@latest
+# 'get example.com/pseudoupgrade@upgrade should not downgrade.
+go get -d example.com/pseudoupgrade@upgrade
 go list -m -u all
 stdout '^example.com/pseudoupgrade v0.0.0-20190430073000-30950c05d534$'
 
+# 'get example.com/pseudoupgrade' should not downgrade.
+go get -d example.com/pseudoupgrade
+go list -m -u all
+stdout '^example.com/pseudoupgrade v0.0.0-20190430073000-30950c05d534$'
+
+# 'get example.com/pseudoupgrade@latest' should downgrade.
+go get -d example.com/pseudoupgrade@latest
+go list -m -u all
+stdout '^example.com/pseudoupgrade v0.1.0$'
+
 -- go.mod --
 module x
 

libgo/go/cmd/go/testdata/script/mod_gobuild_import.txt

@@ -62,15 +62,31 @@ import (
 	"go/build"
 	"log"
 	"os"
+	"path/filepath"
 	"strings"
 )
 
 func main() {
-	p, err := build.Import(os.Args[1], os.Args[2], 0)
+	// build.Import should support relative and absolute source dir paths.
+	path := os.Args[1]
+	srcDir := os.Args[2]
+	p1, err := build.Import(path, srcDir, 0)
 	if err != nil {
 		log.Fatal(err)
 	}
-	fmt.Printf("%s\n%s\n", p.Dir, strings.Join(p.GoFiles, " "))
+	absSrcDir, err := filepath.Abs(srcDir)
+	if err != nil {
+		log.Fatal(err)
+	}
+	p2, err := build.Import(path, absSrcDir, 0)
+	if err != nil {
+		log.Fatal(err)
+	}
+	if p1.Dir != p2.Dir {
+		log.Fatalf("different packages loaded with relative and absolute paths:\n\t%s\n\t%s", p1.Dir, p2.Dir)
+	}
+
+	fmt.Printf("%s\n%s\n", p1.Dir, strings.Join(p1.GoFiles, " "))
 }
 
 -- $GOPATH/other/go.mod --

libgo/go/cmd/go/testdata/script/mod_indirect.txt

+env GO111MODULE=on
+
+# golang.org/issue/31248: module requirements imposed by dependency versions
+# older than the selected version must still be taken into account.
+
+env GOFLAGS=-mod=readonly
+
+# Indirect dependencies required via older-than-selected versions must exist in
+# the module graph, but do not need to be listed explicitly in the go.mod file
+# (since they are implied).
+go mod graph
+stdout i@v0.1.0
+
+# The modules must also appear in the build list, not just the graph.
+go list -m all
+stdout '^i v0.1.0'
+
+# The packages provided by those dependencies must resolve.
+go list all
+stdout '^i$'
+
+-- go.mod --
+module main
+
+go 1.13
+
+require (
+	a v0.0.0
+	b v0.0.0
+	c v0.0.0
+)
+
+// Apply replacements so that the test can be self-contained.
+// (It's easier to see all of the modules here than to go
+// rooting around in testdata/mod.)
+replace (
+	a => ./a
+	b => ./b
+	c => ./c
+	x v0.1.0 => ./x1
+	x v0.2.0 => ./x2
+	i => ./i
+)
+-- main.go --
+package main
+
+import (
+	_ "a"
+	_ "b"
+	_ "c"
+)
+
+func main() {}
+-- a/go.mod --
+module a
+go 1.13
+require x v0.1.0
+-- a/a.go --
+package a
+-- b/go.mod --
+module b
+go 1.13
+require x v0.2.0
+-- b/b.go --
+package b
+-- c/go.mod --
+module c
+go 1.13
+-- c/c.go --
+package c
+import _ "i"
+-- x1/go.mod --
+module x
+go1.13
+require i v0.1.0
+-- x2/go.mod --
+module x
+go1.13
+-- i/go.mod --
+-- i/i.go --
+package i

libgo/go/cmd/go/testdata/script/mod_indirect_main.txt

+env GO111MODULE=on
+
+# Regression test for golang.org/issue/29773: 'go list -m' was not following
+# dependencies through older versions of the main module.
+
+go list -f '{{with .Module}}{{.Path}}{{with .Version}} {{.}}{{end}}{{end}}' all
+cmp stdout pkgmods.txt
+
+go list -m all
+cmp stdout mods.txt
+
+go mod graph
+cmp stdout graph.txt
+
+-- go.mod --
+module golang.org/issue/root
+
+go 1.12
+
+replace (
+	golang.org/issue/mirror v0.1.0 => ./mirror-v0.1.0
+	golang.org/issue/pkg v0.1.0 => ./pkg-v0.1.0
+	golang.org/issue/root v0.1.0 => ./root-v0.1.0
+)
+
+require golang.org/issue/mirror v0.1.0
+
+-- root.go --
+package root
+
+import _ "golang.org/issue/mirror"
+
+-- mirror-v0.1.0/go.mod --
+module golang.org/issue/mirror
+
+require golang.org/issue/root v0.1.0
+
+-- mirror-v0.1.0/mirror.go --
+package mirror
+
+import _ "golang.org/issue/pkg"
+
+-- pkg-v0.1.0/go.mod --
+module golang.org/issue/pkg
+
+-- pkg-v0.1.0/pkg.go --
+package pkg
+
+-- root-v0.1.0/go.mod --
+module golang.org/issue/root
+
+require golang.org/issue/pkg v0.1.0
+
+-- pkgmods.txt --
+golang.org/issue/mirror v0.1.0
+golang.org/issue/pkg v0.1.0
+golang.org/issue/root
+-- mods.txt --
+golang.org/issue/root
+golang.org/issue/mirror v0.1.0 => ./mirror-v0.1.0
+golang.org/issue/pkg v0.1.0 => ./pkg-v0.1.0
+-- graph.txt --
+golang.org/issue/root golang.org/issue/mirror@v0.1.0
+golang.org/issue/mirror@v0.1.0 golang.org/issue/root@v0.1.0
+golang.org/issue/root@v0.1.0 golang.org/issue/pkg@v0.1.0

libgo/go/cmd/go/testdata/script/mod_indirect_tidy.txt

+env GO111MODULE=on
+
+# golang.org/issue/31248: loading the build list must not add explicit entries
+# for indirect dependencies already implied by older-than-selected versions
+# already in the build list.
+
+cp go.mod.orig go.mod
+go mod tidy
+cmp go.mod go.mod.orig
+
+cp go.mod.orig go.mod
+go list -m all
+cmp go.mod go.mod.orig
+
+-- go.mod.orig --
+module main
+
+go 1.13
+
+require a v0.0.0
+
+replace (
+	a v0.0.0 => ./a
+	b v0.0.0 => ./b
+	i v0.0.0 => ./i
+	x v0.1.0 => ./x1
+	x v0.2.0 => ./x2
+)
+-- main.go --
+package main
+
+import _ "a"
+
+func main() {}
+-- a/go.mod --
+module a
+go 1.13
+require (
+	x v0.2.0
+	b v0.0.0
+)
+-- a/a.go --
+package a
+-- b/go.mod --
+module b
+go 1.13
+require x v0.1.0
+-- x1/go.mod --
+module x
+go 1.13
+require (
+	b v0.0.0
+	i v0.0.0
+)
+-- x2/go.mod --
+module x
+go 1.13
+-- i/go.mod --
+module i
+go 1.13

libgo/go/cmd/go/testdata/script/mod_invalid_version.txt

@@ -134,6 +134,19 @@ cd ..
 go list -m golang.org/x/text
 stdout 'golang.org/x/text v0.0.0-0.20170915032832-14c0d48ead0c => golang.org/x/text v0.0.0-20170915032832-14c0d48ead0c'
 
+# A 'replace' directive can replace an invalid 'latest' version, and
+# should suppress errors for that version in 'go get -u'
+cp go.mod.orig go.mod
+go mod edit -require golang.org/x/text@v1.999999.0
+go mod edit -replace golang.org/x/text@v1.999999.0=golang.org/x/text@v0.0.0-20170915032832-14c0d48ead0c
+cd outside
+! go get -d golang.org/x/text@upgrade
+stderr 'go: example.com@v0.0.0 requires\n\tgolang.org/x/text@v1.999999.0: reading golang.org/x/text/go.mod at revision v1.999999.0: unknown revision v1.999999.0'
+cd ..
+go get -d golang.org/x/text@upgrade
+go list -m golang.org/x/text
+stdout 'golang.org/x/text v1.999999.0 => golang.org/x/text v0.0.0-20170915032832-14c0d48ead0c'
+
 # A pseudo-version derived from a non-ancestor tag is invalid.
 cp go.mod.orig go.mod
 go mod edit -require golang.org/x/text@v0.2.1-0.20170915032832-14c0d48ead0c
@@ -144,6 +157,16 @@ cd ..
 ! go list -m golang.org/x/text
 stderr 'golang.org/x/text@v0.2.1-0.20170915032832-14c0d48ead0c: invalid pseudo-version: revision 14c0d48ead0c is not a descendent of preceding tag \(v0.2.0\)'
 
+# A pseudo-version derived from a canonical tag on the same revision is invalid.
+cp go.mod.orig go.mod
+go mod edit -require golang.org/x/text@v0.2.1-0.20171213102548-c4d099d611ac
+cd outside
+! go list -m golang.org/x/text
+stderr 'go: example.com@v0.0.0 requires\n\tgolang.org/x/text@v0.2.1-0.20171213102548-c4d099d611ac: invalid pseudo-version: tag \(v0.2.0\) found on revision c4d099d611ac is already canonical, so should not be replaced with a pseudo-version derived from that tag'
+cd ..
+! go list -m golang.org/x/text
+stderr 'golang.org/x/text@v0.2.1-0.20171213102548-c4d099d611ac: invalid pseudo-version: tag \(v0.2.0\) found on revision c4d099d611ac is already canonical, so should not be replaced with a pseudo-version derived from that tag'
+
 # A +incompatible suffix is not allowed on a version that is actually compatible.
 cp go.mod.orig go.mod
 go mod edit -require golang.org/x/text@v0.1.1-0.20170915032832-14c0d48ead0c+incompatible
@@ -165,15 +188,15 @@ go list -m github.com/pierrec/lz4
 stdout 'github.com/pierrec/lz4 v1.0.2-0.20190131084431-473cd7ce01a1'
 cd ..
 
-# A +incompatible version for a module that has an explicit go.mod file is invalid.
+# A +incompatible pseudo-version for a module that has an explicit go.mod file is invalid.
 cp go.mod.orig go.mod
-go mod edit -require github.com/pierrec/lz4@v2.0.9-0.20190131084431-473cd7ce01a1+incompatible
+go mod edit -require github.com/pierrec/lz4@v2.0.9-0.20190209155647-9a39efadad3d+incompatible
 cd outside
 ! go list -m github.com/pierrec/lz4
-stderr 'go: example.com@v0.0.0 requires\n\tgithub.com/pierrec/lz4@v2.0.9-0.20190131084431-473cd7ce01a1\+incompatible: invalid version: \+incompatible suffix not allowed: module contains a go.mod file, so semantic import versioning is required'
+stderr 'go: example.com@v0.0.0 requires\n\tgithub.com/pierrec/lz4@v2.0.9-0.20190209155647-9a39efadad3d\+incompatible: invalid version: \+incompatible suffix not allowed: module contains a go.mod file, so semantic import versioning is required'
 cd ..
 ! go list -m github.com/pierrec/lz4
-stderr 'github.com/pierrec/lz4@v2.0.9-0.20190131084431-473cd7ce01a1\+incompatible: invalid version: \+incompatible suffix not allowed: module contains a go.mod file, so semantic import versioning is required'
+stderr 'github.com/pierrec/lz4@v2.0.9-0.20190209155647-9a39efadad3d\+incompatible: invalid version: \+incompatible suffix not allowed: module contains a go.mod file, so semantic import versioning is required'
 
 # A +incompatible pseudo-version is valid for a revision of the module
 # that lacks a go.mod file.

libgo/go/cmd/go/testdata/script/mod_list.txt

@@ -34,12 +34,12 @@ go list rsc.io/quote/buggy
 
 # rsc.io/quote/buggy should not be listable as a module
 go list -m -e -f '{{.Error.Err}}' nonexist rsc.io/quote/buggy
-stdout '^module "nonexist" is not a known dependency'
-stdout '^module "rsc.io/quote/buggy" is not a known dependency'
+stdout '^module nonexist: not a known dependency$'
+stdout '^module rsc.io/quote/buggy: not a known dependency$'
 
 ! go list -m nonexist rsc.io/quote/buggy
-stderr '^go list -m nonexist: module "nonexist" is not a known dependency'
-stderr '^go list -m rsc.io/quote/buggy: module "rsc.io/quote/buggy" is not a known dependency'
+stderr '^go list -m: module nonexist: not a known dependency'
+stderr '^go list -m: module rsc.io/quote/buggy: not a known dependency'
 
 # Module loader does not interfere with list -e (golang.org/issue/24149).
 go list -e -f '{{.Error.Err}}' database

libgo/go/cmd/go/testdata/script/mod_list_compiled_concurrent.txt

+env GO111MODULE=on
+
+[short] skip
+
+# Regression test for golang.org/issue/29667:
+# spurious 'failed to cache compiled Go files' errors.
+# This test failed reliably when run with -count=10
+# on a Linux workstation.
+
+env GOCACHE=$WORK/gocache
+mkdir $GOCACHE
+
+go list -json -compiled -test=false -export=false -deps=true -- . &
+go list -json -compiled -test=false -export=false -deps=true -- . &
+go list -json -compiled -test=false -export=false -deps=true -- . &
+go list -json -compiled -test=false -export=false -deps=true -- . &
+go list -json -compiled -test=false -export=false -deps=true -- . &
+go list -json -compiled -test=false -export=false -deps=true -- . &
+go list -json -compiled -test=false -export=false -deps=true -- . &
+go list -json -compiled -test=false -export=false -deps=true -- . &
+go list -json -compiled -test=false -export=false -deps=true -- . &
+go list -json -compiled -test=false -export=false -deps=true -- . &
+go list -json -compiled -test=false -export=false -deps=true -- . &
+go list -json -compiled -test=false -export=false -deps=true -- . &
+go list -json -compiled -test=false -export=false -deps=true -- . &
+go list -json -compiled -test=false -export=false -deps=true -- . &
+go list -json -compiled -test=false -export=false -deps=true -- . &
+go list -json -compiled -test=false -export=false -deps=true -- . &
+go list -json -compiled -test=false -export=false -deps=true -- . &
+go list -json -compiled -test=false -export=false -deps=true -- . &
+go list -json -compiled -test=false -export=false -deps=true -- . &
+go list -json -compiled -test=false -export=false -deps=true -- . &
+
+wait
+
+-- go.mod --
+module sandbox/bar
+-- bar.go --
+package bar
+
+import "C"

libgo/go/cmd/go/testdata/script/mod_list_dir.txt

@@ -12,9 +12,10 @@ stdout ^math$
 go list -f '{{.ImportPath}}' .
 stdout ^x$
 ! go list -f '{{.ImportPath}}' $GOPATH/pkg/mod/rsc.io/quote@v1.5.2
-stderr 'unknown import path "rsc.io/quote": cannot find package'
+stderr '^can.t load package: package '$WORK'[/\\]gopath/pkg/mod/rsc.io/quote@v1.5.2: can only use path@version syntax with .go get.'
+
 go list -e -f '{{with .Error}}{{.}}{{end}}' $GOPATH/pkg/mod/rsc.io/quote@v1.5.2
-stdout 'unknown import path "rsc.io/quote": cannot find package'
+stdout '^package '$WORK'[/\\]gopath/pkg/mod/rsc.io/quote@v1.5.2: can only use path@version syntax with .go get.'
 go mod download rsc.io/quote@v1.5.2
 go list -f '{{.ImportPath}}' $GOPATH/pkg/mod/rsc.io/quote@v1.5.2
 stdout '^rsc.io/quote$'

libgo/go/cmd/go/testdata/script/mod_list_direct.txt

+env GO111MODULE=on
+env GOPROXY=direct
+env GOSUMDB=off
+
+[!net] skip
+[!exec:git] skip
+
+# golang.org/issue/33099: if an import path ends in a major-version suffix,
+# ensure that 'direct' mode can resolve the package to the module.
+# For a while, (*modfetch.codeRepo).Stat was not checking for a go.mod file,
+# which would produce a hard error at the subsequent call to GoMod.
+
+go list all
+
+-- go.mod --
+module example.com
+go 1.13
+
+-- main.go --
+package main
+
+import _ "vcs-test.golang.org/git/v3pkg.git/v3"
+
+func main() {}

libgo/go/cmd/go/testdata/script/mod_list_replace_dir.txt

@@ -6,7 +6,7 @@ env GO111MODULE=on
 go mod download
 
 ! go list $GOPATH/pkg/mod/rsc.io/quote@v1.5.2
-stderr 'outside available modules'
+stderr 'can only use path@version syntax with .go get.'
 
 go list $GOPATH/pkg/mod/rsc.io/quote@v1.5.1
 stdout 'rsc.io/quote'

libgo/go/cmd/go/testdata/script/mod_list_upgrade.txt

 env GO111MODULE=on
 
+# If the current version is not latest, 'go list -u' should include its upgrade.
 go list -m -u all
 stdout 'rsc.io/quote v1.2.0 \[v1\.5\.2\]'
 
+# If the current version is latest, 'go list -u' should omit the upgrade.
+go get -d rsc.io/quote@v1.5.2
+go list -m -u all
+stdout 'rsc.io/quote v1.5.2$'
+
+# If the current version is newer than latest, 'go list -u' should
+# omit the upgrade.
+go get -d rsc.io/quote@v1.5.3-pre1
+go list -m -u all
+stdout 'rsc.io/quote v1.5.3-pre1$'
+
+# If the current build list has a higher version and the user asks about
+# a lower one, -u should report the upgrade for the lower one
+# but leave the build list unchanged.
+go list -m -u rsc.io/quote@v1.5.1
+stdout 'rsc.io/quote v1.5.1 \[v1.5.2\]$'
+go list -m -u rsc.io/quote
+stdout 'rsc.io/quote v1.5.3-pre1$'
+
 -- go.mod --
 module x
 require rsc.io/quote v1.2.0

libgo/go/cmd/go/testdata/script/mod_load_badchain.txt

@@ -57,19 +57,29 @@ import (
 func Test(t *testing.T) {}
 -- update-main-expected --
 go get: example.com/badchain/c@v1.0.0 updating to
-	example.com/badchain/c@v1.1.0: parsing go.mod: unexpected module path "example.com/badchain/wrong"
+	example.com/badchain/c@v1.1.0: parsing go.mod:
+	module declares its path as: badchain.example.com/c
+	        but was required as: example.com/badchain/c
 -- update-a-expected --
 go get: example.com/badchain/a@v1.1.0 requires
 	example.com/badchain/b@v1.1.0 requires
-	example.com/badchain/c@v1.1.0: parsing go.mod: unexpected module path "example.com/badchain/wrong"
+	example.com/badchain/c@v1.1.0: parsing go.mod:
+	module declares its path as: badchain.example.com/c
+	        but was required as: example.com/badchain/c
 -- list-expected --
 go: example.com/badchain/a@v1.1.0 requires
 	example.com/badchain/b@v1.1.0 requires
-	example.com/badchain/c@v1.1.0: parsing go.mod: unexpected module path "example.com/badchain/wrong"
+	example.com/badchain/c@v1.1.0: parsing go.mod:
+	module declares its path as: badchain.example.com/c
+	        but was required as: example.com/badchain/c
 -- list-missing-expected --
 go: m/use imports
-	example.com/badchain/c: example.com/badchain/c@v1.1.0: parsing go.mod: unexpected module path "example.com/badchain/wrong"
+	example.com/badchain/c: example.com/badchain/c@v1.1.0: parsing go.mod:
+	module declares its path as: badchain.example.com/c
+	        but was required as: example.com/badchain/c
 -- list-missing-test-expected --
 go: m/testuse tested by
 	m/testuse.test imports
-	example.com/badchain/c: example.com/badchain/c@v1.1.0: parsing go.mod: unexpected module path "example.com/badchain/wrong"
+	example.com/badchain/c: example.com/badchain/c@v1.1.0: parsing go.mod:
+	module declares its path as: badchain.example.com/c
+	        but was required as: example.com/badchain/c

libgo/go/cmd/go/testdata/script/mod_query.txt

@@ -22,7 +22,7 @@ go list -m rsc.io/quote@<v1.5.4
 stdout 'rsc.io/quote v1.5.2$'
 
 ! go list -m rsc.io/quote@>v1.5.3
-stderr 'go list -m rsc.io/quote: no matching versions for query ">v1.5.3"'
+stderr 'go list -m: module rsc.io/quote: no matching versions for query ">v1.5.3"'
 
 go list -m -e -f '{{.Error.Err}}' rsc.io/quote@>v1.5.3
 stdout 'no matching versions for query ">v1.5.3"'

libgo/go/cmd/go/testdata/script/mod_query_empty.txt

@@ -28,6 +28,20 @@ go list -m example.com/join/...
 ! stdout 'example.com/join/subpkg'
 stdout 'example.com/join v1.1.0'
 
+# If the proxy provides an empty @v/list but rejects @latest with
+# some other explicit error (for example, a "permission denied" error),
+# that error should be reported to the user (and override a successful
+# result for other possible module paths).
+#
+# Depending on how the specific platform enforces permissions, the 'go get' may
+# fail either due to the intended permission error or due to a parse error.
+# We accept either failure message.
+env GOPROXY=file:///$WORK/gatekeeper
+chmod 0000 $WORK/gatekeeper/example.com/join/subpkg/@latest
+cp go.mod.orig go.mod
+! go get -d example.com/join/subpkg
+stderr 'go get example.com/join/subpkg: module example.com/join/subpkg: (invalid character .+|reading file://.*/gatekeeper/example.com/join/subpkg/@latest: .+)'
+
 -- go.mod.orig --
 module example.com/othermodule
 go 1.13
@@ -50,3 +64,10 @@ v1.0.0-does-not-exist
 v1.1.0
 -- $WORK/notfound/example.com/join/@v/v1.1.0.info --
 {"Version": "v1.1.0"}
+-- $WORK/gatekeeper/example.com/join/subpkg/@v/list --
+-- $WORK/gatekeeper/example.com/join/subpkg/@latest --
+ERROR: Latest version is forbidden.
+-- $WORK/gatekeeper/example.com/join/@v/list --
+v1.1.0
+-- $WORK/gatekeeper/example.com/join/@v/v1.1.0.info --
+{"Version": "v1.1.0"}

libgo/go/cmd/go/testdata/script/mod_sumdb.txt

@@ -9,8 +9,8 @@ env dbname=localhost.localdev/sumdb
 cp go.mod.orig go.mod
 env GOSUMDB=$sumdb' '$proxy/sumdb-wrong
 ! go get -d rsc.io/quote
-stderr 'verifying rsc.io/quote@v1.5.2/go.mod: checksum mismatch'
-stderr 'downloaded: h1:LzX7'
+stderr 'verifying rsc.io/quote@v1.5.2: checksum mismatch'
+stderr 'downloaded: h1:3fEy'
 stderr 'localhost.localdev/sumdb: h1:wrong'
 stderr 'SECURITY ERROR\nThis download does NOT match the one reported by the checksum server.'
 ! go get -d rsc.io/sampler

libgo/go/cmd/go/testdata/script/mod_sumdb_cache.txt

@@ -28,7 +28,7 @@ cp go.mod.orig go.mod
 rm go.sum
 env GOPROXY=off
 go get -d rsc.io/quote@v1.5.2 # using cache
-rm $GOPATH/pkg/mod/download/cache/sumdb/localhost.localdev/sumdb/lookup/rsc.io/quote@v1.5.2
+rm $GOPATH/pkg/mod/cache/download/sumdb/localhost.localdev/sumdb/lookup/rsc.io/quote@v1.5.2
 go get -d rsc.io/quote@v1.5.2 # using go.sum
 
 # fetch fails once we lose access to both cache and go.sum

libgo/go/cmd/go/testdata/script/mod_sumdb_file_path.txt

@@ -2,6 +2,7 @@
 
 env GO111MODULE=on
 env GOSUMDB=
+env GOPATH=$WORK/gopath1
 
 # With a file-based proxy with an empty checksum directory,
 # downloading a new module should fail, even if a subsequent
@@ -18,11 +19,20 @@ stderr '^verifying golang.org/x/text.*: Not Found'
 [!windows] env GOPROXY=file://$WORK/emptyproxy,https://proxy.golang.org
 go get -d golang.org/x/text@v0.3.2
 
+# After a successful sumdb lookup, the lookup can be repeated
+# using the download cache as a proxy.
+cp supported $GOPATH/pkg/mod/cache/download/sumdb/sum.golang.org/supported
+[windows] env GOPROXY=file:///$WORK/gopath1/pkg/mod/cache/download,file:///$WORK/sumproxy
+[!windows] env GOPROXY=file://$WORK/gopath1/pkg/mod/cache/download,file://$WORK/sumproxy
+env GOPATH=$WORK/gopath2
+rm go.sum
+go get -d -x -v golang.org/x/text@v0.3.2
+
 # Once the checksum is present in the go.sum file,
 # an empty file-based sumdb can be used in conjunction with
 # a fallback module mirror.
 grep golang.org/x/text go.sum
-go clean -modcache
+env GOPATH=$WORK/gopath3
 [windows] env GOPROXY=file:///$WORK/sumproxy
 [!windows] env GOPROXY=file://$WORK/sumproxy
 ! go get -d golang.org/x/text@v0.3.2
@@ -30,6 +40,8 @@ go clean -modcache
 [!windows] env GOPROXY=file://$WORK/sumproxy,https://proxy.golang.org
 go get -d golang.org/x/text@v0.3.2
 
+-- supported --
+
 -- go.mod --
 module example.com
 go 1.13

libgo/go/cmd/go/testdata/script/mod_sumdb_golang.txt

@@ -14,31 +14,39 @@ stdout '^sum.golang.org$'
 [!exec:git] skip
 env GOSUMDB=sum.golang.org
 env GOPROXY=direct
-go get -d rsc.io/quote
+go get -d rsc.io/quote@v1.5.2
+cp go.sum saved.sum
 
 # download from proxy.golang.org with go.sum entry already
 go clean -modcache
 env GOSUMDB=
 env GOPROXY=
-go get -x -d rsc.io/quote
+go get -x -d rsc.io/quote@v1.5.2
 ! stderr github
 stderr proxy.golang.org/rsc.io/quote
 ! stderr sum.golang.org/tile
 ! stderr sum.golang.org/lookup/rsc.io/quote
+cmp go.sum saved.sum
 
-# download again, using checksum database to validate new go.sum lines
+# Download again.
+# Should use the checksum database to validate new go.sum lines,
+# but not need to fetch any new data from the proxy.
 rm go.sum
-go get -x -d rsc.io/quote
+go get -x -d rsc.io/quote@v1.5.2
 ! stderr github
-stderr proxy.golang.org/rsc.io/quote
+! stderr proxy.golang.org/rsc.io/quote
 stderr sum.golang.org/tile
 stderr sum.golang.org/lookup/rsc.io/quote
+cmp go.sum saved.sum
 
 # test fallback to direct
 env TESTGOPROXY404=1
-go get -x -d rsc.io/quote
+go clean -modcache
+rm go.sum
+go get -x -d rsc.io/quote@v1.5.2
 stderr 'proxy.golang.org.*404 testing'
 stderr github.com/rsc
+cmp go.sum saved.sum
 
 -- go.mod --
 module m

libgo/go/cmd/go/testdata/script/mod_sumdb_proxy.txt

@@ -6,14 +6,14 @@ env GOPROXY GONOPROXY GOSUMDB GONOSUMDB
 # basic fetch (through proxy) works
 cp go.mod.orig go.mod
 go get -d rsc.io/fortune@v1.0.0 # note: must use test proxy, does not exist in real world
-rm $GOPATH/pkg/mod/download/cache/sumdb # rm sumdb cache but NOT package download cache
+rm $GOPATH/pkg/mod/cache/download/sumdb # rm sumdb cache but NOT package download cache
 rm go.sum
 
 # can fetch by explicit URL
 cp go.mod.orig go.mod
 env GOSUMDB=$sumdb' '$proxy/sumdb-direct
 go get -d rsc.io/fortune@v1.0.0
-rm $GOPATH/pkg/mod/download/cache/sumdb
+rm $GOPATH/pkg/mod/cache/download/sumdb
 rm go.sum
 
 # direct access fails (because localhost.localdev does not exist)
@@ -25,7 +25,7 @@ env GOSUMDB=$sumdb
 env GOPROXY=direct
 ! go get -d rsc.io/fortune@v1.0.0
 stderr 'verifying.*localhost.localdev'
-rm $GOPATH/pkg/mod/download/cache/sumdb
+rm $GOPATH/pkg/mod/cache/download/sumdb
 rm go.sum
 
 # proxy 404 falls back to direct access (which fails)
@@ -34,7 +34,7 @@ env GOSUMDB=$sumdb
 env GOPROXY=$proxy/sumdb-404
 ! go get -d rsc.io/fortune@v1.0.0
 stderr 'verifying.*localhost.localdev'
-rm $GOPATH/pkg/mod/download/cache/sumdb
+rm $GOPATH/pkg/mod/cache/download/sumdb
 rm go.sum
 
 # proxy non-200/404/410 stops direct access
@@ -43,7 +43,7 @@ env GOSUMDB=$sumdb
 env GOPROXY=$proxy/sumdb-503
 ! go get -d rsc.io/fortune@v1.0.0
 stderr '503 Service Unavailable'
-rm $GOPATH/pkg/mod/download/cache/sumdb
+rm $GOPATH/pkg/mod/cache/download/sumdb
 rm go.sum
 
 -- go.mod.orig --

libgo/go/cmd/go/testdata/script/mod_test_cached.txt

+[short] skip
+
+env GO111MODULE=on
+env GOCACHE=$WORK/gocache
+env GODEBUG=gocachetest=1
+
+# The first run of a test should not be cached.
+# The second run should be.
+go test -run=WriteTmp .
+! stdout '(cached)'
+go test -run=WriteTmp .
+stdout '(cached)'
+
+# 'go test' without arguments should never be cached.
+go test -run=WriteTmp
+! stdout '(cached)'
+go test -run=WriteTmp
+! stdout '(cached)'
+
+# We should never cache a test run from command-line files.
+go test -run=WriteTmp ./foo_test.go
+! stdout '(cached)'
+go test -run=WriteTmp ./foo_test.go
+! stdout '(cached)'
+
+[!exec:sleep] stop
+# The go command refuses to cache access to files younger than 2s, so sleep that long.
+exec sleep 2
+
+# Touching a file that the test reads from within its testdata should invalidate the cache.
+go test -run=ReadTestdata .
+! stdout '(cached)'
+go test -run=ReadTestdata .
+stdout '(cached)'
+cp testdata/bar.txt testdata/foo.txt
+go test -run=ReadTestdata .
+! stdout '(cached)'
+
+-- go.mod --
+module golang.org/issue/29111/foo
+
+-- foo.go --
+package foo
+
+-- testdata/foo.txt --
+foo
+-- testdata/bar.txt --
+bar
+
+-- foo_test.go --
+package foo_test
+
+import (
+	"io/ioutil"
+	"os"
+	"path/filepath"
+	"testing"
+)
+
+func TestWriteTmp(t *testing.T) {
+	dir, err := ioutil.TempDir("", "")
+	if err != nil {
+		t.Fatal(err)
+	}
+	defer os.RemoveAll(dir)
+	err = ioutil.WriteFile(filepath.Join(dir, "x"), nil, 0666)
+	if err != nil {
+		t.Fatal(err)
+	}
+}
+
+func TestReadTestdata(t *testing.T) {
+	_, err := ioutil.ReadFile("testdata/foo.txt")
+	if err != nil {
+		t.Fatal(err)
+	}
+}

libgo/go/cmd/go/testdata/script/mod_tidy_error.txt

+env GO111MODULE=on
+
+# Regression test for golang.org/issue/27063:
+# 'go mod tidy' and 'go mod vendor' should not hide loading errors.
+
+! go mod tidy
+stderr '^issue27063 imports\n\tnonexist: malformed module path "nonexist": missing dot in first path element'
+stderr '^issue27063 imports\n\tnonexist.example.com: cannot find module providing package nonexist.example.com'
+stderr '^issue27063 imports\n\tissue27063/other imports\n\tother.example.com/nonexist: cannot find module providing package other.example.com/nonexist'
+
+! go mod vendor
+stderr '^issue27063 imports\n\tnonexist: malformed module path "nonexist": missing dot in first path element'
+stderr '^issue27063 imports\n\tnonexist.example.com: cannot find module providing package nonexist.example.com'
+stderr '^issue27063 imports\n\tissue27063/other imports\n\tother.example.com/nonexist: cannot find module providing package other.example.com/nonexist'
+
+-- go.mod --
+module issue27063
+
+go 1.13
+
+require issue27063/other v0.0.0
+replace issue27063/other => ./other
+-- x.go --
+package main
+
+import (
+	"nonexist"
+
+	"nonexist.example.com"
+	"issue27063/other"
+)
+
+func main() {}
+-- other/go.mod --
+module issue27063/other
+-- other/other.go --
+package other
+
+import "other.example.com/nonexist"

libgo/go/cmd/go/testdata/script/mod_vendor.txt

@@ -171,12 +171,6 @@ package m
 
 import _ "appengine"
 import _ "appengine/datastore"
--- nonexistent.go --
-// +build alternatereality
-
-package m
-
-import _ "nonexistent.rsc.io"
 -- mypkg/go.mod --
 module me
 -- mypkg/mydir/d.go --

libgo/go/cmd/go/testdata/script/test_go111module_cache.txt

+env GO111MODULE=on
+go mod init foo
+go test
+stdout ^ok\s+foo
+env GO111MODULE=off
+go test
+stdout ^ok\s+
+! stdout ^ok\s+(cache)$
+
+-- main_test.go --
+package main
+
+import "testing"
+
+func TestF(t *testing.T) {}

libgo/go/cmd/go/testdata/script/test_init.txt

-# Tests for automatic testing.Init calls when using 'go test'.
-
-env GO111MODULE=on
-
-# A TestMain should be able to access testing flags if it calls flag.Parse
-# without needing to use testing.Init.
-# Test code can use the name 'testing' without colliding with generated
-# testinginit code.
-# Tests running under 'go test' should observe that testing.Init is called
-# before any user package initialization code runs.
-go test
-stdout TestMain
-stdout TestInit
-stdout TestExt
-
--- go.mod --
-module m
-
--- init_test.go --
-package testinitflag
-
-import (
-	"flag"
-	"fmt"
-	"os"
-	Testing "testing"
-)
-
-func testFlagsInitialized() bool {
-	found := false
-	flag.VisitAll(func(f *flag.Flag) {
-		if f.Name == "test.count" {
-			found = true
-		}
-	})
-	return found
-}
-
-var testing int
-var testingInitAtInitialization = testFlagsInitialized()
-
-func TestInit(t *Testing.T) {
-	if !testingInitAtInitialization {
-		t.Fatal("testing.Init not called before package initialization")
-	}
-	fmt.Printf("TestInit\n")
-}
-
-func TestMain(m *Testing.M) {
-	fmt.Printf("TestMain\n")
-	flag.Parse()
-	if !testFlagsInitialized() {
-		fmt.Println("testing flags not registered")
-		os.Exit(1)
-	}
-	os.Exit(m.Run())
-}
-
--- external_test.go --
-package testinitflag_test
-
-import (
-	"flag"
-	"fmt"
-	Testing "testing"
-)
-
-func testFlagsInitialized() bool {
-	found := false
-	flag.VisitAll(func(f *flag.Flag) {
-		if f.Name == "test.count" {
-			found = true
-		}
-	})
-	return found
-}
-
-var testing int
-var testingInitAtInitialization = testFlagsInitialized()
-
-func TestExt(t *Testing.T) {
-	fmt.Printf("TestExt\n")
-	if !testingInitAtInitialization {
-		t.Fatal("testing.Init not called before package initialization")
-	}
-}

libgo/go/cmd/go/testdata/script/version.txt

@@ -8,5 +8,12 @@ go version -m fortune.exe
 stdout '^\tpath\trsc.io/fortune'
 stdout '^\tmod\trsc.io/fortune\tv1.0.0'
 
+go build -buildmode=pie -o external.exe rsc.io/fortune
+go version external.exe
+stdout '^external.exe: .+'
+go version -m external.exe
+stdout '^\tpath\trsc.io/fortune'
+stdout '^\tmod\trsc.io/fortune\tv1.0.0'
+
 -- go.mod --
 module m

libgo/go/cmd/go/testdata/standalone_testmain_flag_test.go

+// Copyright 2019 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 standalone_testmain_flag_test
+
+import (
+	"flag"
+	"fmt"
+	"os"
+	"testing"
+)
+
+func TestMain(m *testing.M) {
+	// A TestMain should be able to access testing flags if it calls
+	// flag.Parse without needing to use testing.Init.
+	flag.Parse()
+	found := false
+	flag.VisitAll(func(f *flag.Flag) {
+		if f.Name == "test.count" {
+			found = true
+		}
+	})
+	if !found {
+		fmt.Println("testing flags not registered")
+		os.Exit(1)
+	}
+	os.Exit(m.Run())
+}

libgo/go/cmd/gofmt/testdata/go2numbers.golden

+package p
+
+const (
+	// 0-octals
+	_ = 0
+	_ = 0123
+	_ = 0123456
+
+	_ = 0_123
+	_ = 0123_456
+
+	// decimals
+	_ = 1
+	_ = 1234
+	_ = 1234567
+
+	_ = 1_234
+	_ = 1_234_567
+
+	// hexadecimals
+	_ = 0x0
+	_ = 0x1234
+	_ = 0xcafef00d
+
+	_ = 0x0
+	_ = 0x1234
+	_ = 0xCAFEf00d
+
+	_ = 0x_0
+	_ = 0x_1234
+	_ = 0x_CAFE_f00d
+
+	// octals
+	_ = 0o0
+	_ = 0o1234
+	_ = 0o01234567
+
+	_ = 0o0
+	_ = 0o1234
+	_ = 0o01234567
+
+	_ = 0o_0
+	_ = 0o_1234
+	_ = 0o0123_4567
+
+	_ = 0o_0
+	_ = 0o_1234
+	_ = 0o0123_4567
+
+	// binaries
+	_ = 0b0
+	_ = 0b1011
+	_ = 0b00101101
+
+	_ = 0b0
+	_ = 0b1011
+	_ = 0b00101101
+
+	_ = 0b_0
+	_ = 0b10_11
+	_ = 0b_0010_1101
+
+	// decimal floats
+	_ = 0.
+	_ = 123.
+	_ = 0123.
+
+	_ = .0
+	_ = .123
+	_ = .0123
+
+	_ = 0e0
+	_ = 123e+0
+	_ = 0123e-1
+
+	_ = 0e-0
+	_ = 123e+0
+	_ = 0123e123
+
+	_ = 0.e+1
+	_ = 123.e-10
+	_ = 0123.e123
+
+	_ = .0e-1
+	_ = .123e+10
+	_ = .0123e123
+
+	_ = 0.0
+	_ = 123.123
+	_ = 0123.0123
+
+	_ = 0.0e1
+	_ = 123.123e-10
+	_ = 0123.0123e+456
+
+	_ = 1_2_3.
+	_ = 0_123.
+
+	_ = 0_0e0
+	_ = 1_2_3e0
+	_ = 0_123e0
+
+	_ = 0e-0_0
+	_ = 1_2_3e+0
+	_ = 0123e1_2_3
+
+	_ = 0.e+1
+	_ = 123.e-1_0
+	_ = 01_23.e123
+
+	_ = .0e-1
+	_ = .123e+10
+	_ = .0123e123
+
+	_ = 1_2_3.123
+	_ = 0123.01_23
+
+	// hexadecimal floats
+	_ = 0x0.p+0
+	_ = 0xdeadcafe.p-10
+	_ = 0x1234.p123
+
+	_ = 0x.1p-0
+	_ = 0x.deadcafep2
+	_ = 0x.1234p+10
+
+	_ = 0x0p0
+	_ = 0xdeadcafep+1
+	_ = 0x1234p-10
+
+	_ = 0x0.0p0
+	_ = 0xdead.cafep+1
+	_ = 0x12.34p-10
+
+	_ = 0xdead_cafep+1
+	_ = 0x_1234p-10
+
+	_ = 0x_dead_cafe.p-10
+	_ = 0x12_34.p1_2_3
+	_ = 0x1_2_3_4.p-1_2_3
+
+	// imaginaries
+	_ = 0i
+	_ = 0i
+	_ = 8i
+	_ = 0i
+	_ = 123i
+	_ = 123i
+	_ = 56789i
+	_ = 1234i
+	_ = 1234567i
+
+	_ = 0i
+	_ = 0i
+	_ = 8i
+	_ = 0i
+	_ = 123i
+	_ = 123i
+	_ = 56_789i
+	_ = 1_234i
+	_ = 1_234_567i
+
+	_ = 0.i
+	_ = 123.i
+	_ = 0123.i
+	_ = 000123.i
+
+	_ = 0e0i
+	_ = 123e0i
+	_ = 0123e0i
+	_ = 000123e0i
+
+	_ = 0.e+1i
+	_ = 123.e-1_0i
+	_ = 01_23.e123i
+	_ = 00_01_23.e123i
+
+	_ = 0b1010i
+	_ = 0b1010i
+	_ = 0o660i
+	_ = 0o660i
+	_ = 0xabcDEFi
+	_ = 0xabcDEFi
+	_ = 0xabcDEFp0i
+	_ = 0xabcDEFp0i
+)

libgo/go/cmd/gofmt/testdata/go2numbers.input

+package p
+
+const (
+	// 0-octals
+	_ = 0
+	_ = 0123
+	_ = 0123456
+
+	_ = 0_123
+	_ = 0123_456
+
+	// decimals
+	_ = 1
+	_ = 1234
+	_ = 1234567
+
+	_ = 1_234
+	_ = 1_234_567
+
+	// hexadecimals
+	_ = 0x0
+	_ = 0x1234
+	_ = 0xcafef00d
+
+	_ = 0X0
+	_ = 0X1234
+	_ = 0XCAFEf00d
+
+	_ = 0X_0
+	_ = 0X_1234
+	_ = 0X_CAFE_f00d
+
+	// octals
+	_ = 0o0
+	_ = 0o1234
+	_ = 0o01234567
+
+	_ = 0O0
+	_ = 0O1234
+	_ = 0O01234567
+
+	_ = 0o_0
+	_ = 0o_1234
+	_ = 0o0123_4567
+
+	_ = 0O_0
+	_ = 0O_1234
+	_ = 0O0123_4567
+
+	// binaries
+	_ = 0b0
+	_ = 0b1011
+	_ = 0b00101101
+
+	_ = 0B0
+	_ = 0B1011
+	_ = 0B00101101
+
+	_ = 0b_0
+	_ = 0b10_11
+	_ = 0b_0010_1101
+
+	// decimal floats
+	_ = 0.
+	_ = 123.
+	_ = 0123.
+
+	_ = .0
+	_ = .123
+	_ = .0123
+
+	_ = 0e0
+	_ = 123e+0
+	_ = 0123E-1
+
+	_ = 0e-0
+	_ = 123E+0
+	_ = 0123E123
+
+	_ = 0.e+1
+	_ = 123.E-10
+	_ = 0123.e123
+
+	_ = .0e-1
+	_ = .123E+10
+	_ = .0123E123
+
+	_ = 0.0
+	_ = 123.123
+	_ = 0123.0123
+
+	_ = 0.0e1
+	_ = 123.123E-10
+	_ = 0123.0123e+456
+
+	_ = 1_2_3.
+	_ = 0_123.
+
+	_ = 0_0e0
+	_ = 1_2_3e0
+	_ = 0_123e0
+
+	_ = 0e-0_0
+	_ = 1_2_3E+0
+	_ = 0123E1_2_3
+
+	_ = 0.e+1
+	_ = 123.E-1_0
+	_ = 01_23.e123
+
+	_ = .0e-1
+	_ = .123E+10
+	_ = .0123E123
+
+	_ = 1_2_3.123
+	_ = 0123.01_23
+
+	// hexadecimal floats
+	_ = 0x0.p+0
+	_ = 0Xdeadcafe.p-10
+	_ = 0x1234.P123
+
+	_ = 0x.1p-0
+	_ = 0X.deadcafep2
+	_ = 0x.1234P+10
+
+	_ = 0x0p0
+	_ = 0Xdeadcafep+1
+	_ = 0x1234P-10
+
+	_ = 0x0.0p0
+	_ = 0Xdead.cafep+1
+	_ = 0x12.34P-10
+
+	_ = 0Xdead_cafep+1
+	_ = 0x_1234P-10
+
+	_ = 0X_dead_cafe.p-10
+	_ = 0x12_34.P1_2_3
+	_ = 0X1_2_3_4.P-1_2_3
+
+	// imaginaries
+	_ = 0i
+	_ = 00i
+	_ = 08i
+	_ = 0000000000i
+	_ = 0123i
+	_ = 0000000123i
+	_ = 0000056789i
+	_ = 1234i
+	_ = 1234567i
+
+	_ = 0i
+	_ = 0_0i
+	_ = 0_8i
+	_ = 0_000_000_000i
+	_ = 0_123i
+	_ = 0_000_000_123i
+	_ = 0_000_056_789i
+	_ = 1_234i
+	_ = 1_234_567i
+
+	_ = 0.i
+	_ = 123.i
+	_ = 0123.i
+	_ = 000123.i
+
+	_ = 0e0i
+	_ = 123e0i
+	_ = 0123E0i
+	_ = 000123E0i
+
+	_ = 0.e+1i
+	_ = 123.E-1_0i
+	_ = 01_23.e123i
+	_ = 00_01_23.e123i
+
+	_ = 0b1010i
+	_ = 0B1010i
+	_ = 0o660i
+	_ = 0O660i
+	_ = 0xabcDEFi
+	_ = 0XabcDEFi
+	_ = 0xabcDEFP0i
+	_ = 0XabcDEFp0i
+)

libgo/go/cmd/gofmt/testdata/import.golden

@@ -10,6 +10,11 @@ import (
 
 import (
 	"fmt"
+	"math"
+)
+
+import (
+	"fmt"
 
 	"math"
 

libgo/go/cmd/gofmt/testdata/import.input

@@ -8,6 +8,9 @@ import (
 	"io"
 )
 
+import("fmt"
+"math")
+
 import (
 	"fmt"
 

libgo/go/cmd/gofmt/testdata/rewrite9.golden

+//gofmt -r=a&&b!=2->a
+
+// Copyright 2017 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.
+
+// Issue 18987.
+
+package p
+
+const _ = x != 1

libgo/go/cmd/gofmt/testdata/rewrite9.input

+//gofmt -r=a&&b!=2->a
+
+// Copyright 2017 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.
+
+// Issue 18987.
+
+package p
+
+const _ = x != 1 && x != 2

libgo/go/cmd/gofmt/testdata/typealias.golden

+package q
+
+import "p"
+
+type _ = int
+type a = struct{ x int }
+type b = p.B
+
+type (
+	_  = chan<- int
+	aa = interface{}
+	bb = p.BB
+)
+
+// TODO(gri) We may want to put the '=' into a separate column if
+// we have mixed (regular and alias) type declarations in a group.
+type (
+	_   chan<- int
+	_   = chan<- int
+	aa0 interface{}
+	aaa = interface{}
+	bb0 p.BB
+	bbb = p.BB
+)

libgo/go/cmd/gofmt/testdata/typealias.input

+package q
+
+import "p"
+
+type _ = int
+type a = struct{ x int }
+type b = p.B
+
+type (
+	_ = chan<- int
+	aa = interface{}
+	bb = p.BB
+)
+
+// TODO(gri) We may want to put the '=' into a separate column if
+// we have mixed (regular and alias) type declarations in a group.
+type (
+	_ chan<- int
+	_ = chan<- int
+	aa0 interface{}
+	aaa = interface{}
+	bb0 p.BB
+	bbb = p.BB
+)

libgo/go/cmd/internal/objabi/flag.go

@@ -86,6 +86,10 @@ func (versionFlag) Set(s string) error {
 	name = name[strings.LastIndex(name, `/`)+1:]
 	name = name[strings.LastIndex(name, `\`)+1:]
 	name = strings.TrimSuffix(name, ".exe")
+
+	// If there's an active experiment, include that,
+	// to distinguish go1.10.2 with an experiment
+	// from go1.10.2 without an experiment.
 	p := Expstring()
 	if p == DefaultExpstring() {
 		p = ""
@@ -101,12 +105,6 @@ func (versionFlag) Set(s string) error {
 	// build ID of the binary, so that if the compiler is changed and
 	// rebuilt, we notice and rebuild all packages.
 	if s == "full" {
-		// If there's an active experiment, include that,
-		// to distinguish go1.10.2 with an experiment
-		// from go1.10.2 without an experiment.
-		if x := Expstring(); x != "" {
-			p += " " + x
-		}
 		if strings.HasPrefix(Version, "devel") {
 			p += " buildID=" + buildID
 		}

libgo/go/context/context.go

@@ -49,7 +49,6 @@ package context
 
 import (
 	"errors"
-	"internal/oserror"
 	"internal/reflectlite"
 	"sync"
 	"time"
@@ -163,9 +162,6 @@ type deadlineExceededError struct{}
 func (deadlineExceededError) Error() string   { return "context deadline exceeded" }
 func (deadlineExceededError) Timeout() bool   { return true }
 func (deadlineExceededError) Temporary() bool { return true }
-func (deadlineExceededError) Is(target error) bool {
-	return target == oserror.ErrTimeout || target == oserror.ErrTemporary
-}
 
 // An emptyCtx is never canceled, has no values, and has no deadline. It is not
 // struct{}, since vars of this type must have distinct addresses.

libgo/go/context/context_test.go

@@ -5,10 +5,8 @@
 package context
 
 import (
-	"errors"
 	"fmt"
 	"math/rand"
-	"os"
 	"runtime"
 	"strings"
 	"sync"
@@ -649,7 +647,4 @@ func XTestDeadlineExceededSupportsTimeout(t testingT) {
 	if !i.Timeout() {
 		t.Fatal("wrong value for timeout")
 	}
-	if !errors.Is(DeadlineExceeded, os.ErrTimeout) {
-		t.Fatal("errors.Is(DeadlineExceeded, os.ErrTimeout) = false, want true")
-	}
 }

libgo/go/crypto/rsa/rsa.go

@@ -555,7 +555,7 @@ func decryptAndCheck(random io.Reader, priv *PrivateKey, c *big.Int) (m *big.Int
 }
 
 // DecryptOAEP decrypts ciphertext using RSA-OAEP.
-
+//
 // OAEP is parameterised by a hash function that is used as a random oracle.
 // Encryption and decryption of a given message must use the same hash function
 // and sha256.New() is a reasonable choice.

libgo/go/crypto/tls/common.go

@@ -23,11 +23,14 @@ import (
 )
 
 const (
-	VersionSSL30 = 0x0300
 	VersionTLS10 = 0x0301
 	VersionTLS11 = 0x0302
 	VersionTLS12 = 0x0303
 	VersionTLS13 = 0x0304
+
+	// Deprecated: SSLv3 is cryptographically broken, and will be
+	// removed in Go 1.14. See golang.org/issue/32716.
+	VersionSSL30 = 0x0300
 )
 
 const (
@@ -791,6 +794,10 @@ var supportedVersions = []uint16{
 func (c *Config) supportedVersions(isClient bool) []uint16 {
 	versions := make([]uint16, 0, len(supportedVersions))
 	for _, v := range supportedVersions {
+		// TLS 1.0 is the default minimum version.
+		if (c == nil || c.MinVersion == 0) && v < VersionTLS10 {
+			continue
+		}
 		if c != nil && c.MinVersion != 0 && v < c.MinVersion {
 			continue
 		}

libgo/go/crypto/tls/handshake_server_test.go

@@ -77,6 +77,20 @@ func TestRejectBadProtocolVersion(t *testing.T) {
 	}, "unsupported versions")
 }
 
+func TestSSLv3OptIn(t *testing.T) {
+	config := testConfig.Clone()
+	config.MinVersion = 0
+	testClientHelloFailure(t, config, &clientHelloMsg{
+		vers:   VersionSSL30,
+		random: make([]byte, 32),
+	}, "unsupported versions")
+	testClientHelloFailure(t, config, &clientHelloMsg{
+		vers:              VersionTLS12,
+		supportedVersions: []uint16{VersionSSL30},
+		random:            make([]byte, 32),
+	}, "unsupported versions")
+}
+
 func TestNoSuiteOverlap(t *testing.T) {
 	clientHello := &clientHelloMsg{
 		vers:               VersionTLS10,

libgo/go/crypto/tls/handshake_test.go

@@ -222,28 +222,65 @@ func tempFile(contents string) string {
 // localListener is set up by TestMain and used by localPipe to create Conn
 // pairs like net.Pipe, but connected by an actual buffered TCP connection.
 var localListener struct {
-	sync.Mutex
-	net.Listener
+	mu   sync.Mutex
+	addr net.Addr
+	ch   chan net.Conn
+}
+
+const localFlakes = 0 // change to 1 or 2 to exercise localServer/localPipe handling of mismatches
+
+func localServer(l net.Listener) {
+	for n := 0; ; n++ {
+		c, err := l.Accept()
+		if err != nil {
+			return
+		}
+		if localFlakes == 1 && n%2 == 0 {
+			c.Close()
+			continue
+		}
+		localListener.ch <- c
+	}
 }
 
 func localPipe(t testing.TB) (net.Conn, net.Conn) {
-	localListener.Lock()
-	defer localListener.Unlock()
-	c := make(chan net.Conn)
-	go func() {
-		conn, err := localListener.Accept()
+	localListener.mu.Lock()
+	defer localListener.mu.Unlock()
+
+	addr := localListener.addr
+
+Dialing:
+	// We expect a rare mismatch, but probably not 5 in a row.
+	for i := 0; i < 5; i++ {
+		tooSlow := time.NewTimer(1 * time.Second)
+		defer tooSlow.Stop()
+		c1, err := net.Dial(addr.Network(), addr.String())
 		if err != nil {
-			t.Errorf("Failed to accept local connection: %v", err)
+			t.Fatalf("localPipe: %v", err)
+		}
+		if localFlakes == 2 && i == 0 {
+			c1.Close()
+			continue
+		}
+		for {
+			select {
+			case <-tooSlow.C:
+				t.Logf("localPipe: timeout waiting for %v", c1.LocalAddr())
+				c1.Close()
+				continue Dialing
+
+			case c2 := <-localListener.ch:
+				if c2.RemoteAddr().String() == c1.LocalAddr().String() {
+					return c1, c2
+				}
+				t.Logf("localPipe: unexpected connection: %v != %v", c2.RemoteAddr(), c1.LocalAddr())
+				c2.Close()
+			}
 		}
-		c <- conn
-	}()
-	addr := localListener.Addr()
-	c1, err := net.Dial(addr.Network(), addr.String())
-	if err != nil {
-		t.Fatalf("Failed to dial local connection: %v", err)
 	}
-	c2 := <-c
-	return c1, c2
+
+	t.Fatalf("localPipe: failed to connect")
+	panic("unreachable")
 }
 
 // zeroSource is an io.Reader that returns an unlimited number of zero bytes.
@@ -293,8 +330,10 @@ func runMain(m *testing.M) int {
 		fmt.Fprintf(os.Stderr, "Failed to open local listener: %v", err)
 		os.Exit(1)
 	}
-	localListener.Listener = l
-	defer localListener.Close()
+	localListener.ch = make(chan net.Conn)
+	localListener.addr = l.Addr()
+	defer l.Close()
+	go localServer(l)
 
 	if err := checkOpenSSLVersion(); err != nil {
 		fmt.Fprintf(os.Stderr, "Error: %v", err)

libgo/go/crypto/tls/tls_test.go

@@ -359,50 +359,6 @@ func TestVerifyHostname(t *testing.T) {
 	}
 }
 
-func TestVerifyHostnameResumed(t *testing.T) {
-	t.Run("TLSv12", func(t *testing.T) { testVerifyHostnameResumed(t, VersionTLS12) })
-	t.Run("TLSv13", func(t *testing.T) { testVerifyHostnameResumed(t, VersionTLS13) })
-}
-
-func testVerifyHostnameResumed(t *testing.T, version uint16) {
-	testenv.MustHaveExternalNetwork(t)
-
-	config := &Config{
-		MaxVersion:         version,
-		ClientSessionCache: NewLRUClientSessionCache(32),
-	}
-	for i := 0; i < 2; i++ {
-		c, err := DialWithDialer(&net.Dialer{
-			Timeout: 10 * time.Second,
-		}, "tcp", "mail.google.com:https", config)
-		if err != nil {
-			t.Fatalf("Dial #%d: %v", i, err)
-		}
-		cs := c.ConnectionState()
-		if i > 0 && !cs.DidResume {
-			t.Fatalf("Subsequent connection unexpectedly didn't resume")
-		}
-		if cs.Version != version {
-			t.Fatalf("Unexpectedly negotiated version %x", cs.Version)
-		}
-		if cs.VerifiedChains == nil {
-			t.Fatalf("Dial #%d: cs.VerifiedChains == nil", i)
-		}
-		if err := c.VerifyHostname("mail.google.com"); err != nil {
-			t.Fatalf("verify mail.google.com #%d: %v", i, err)
-		}
-		// Have the server send some data so session tickets are delivered.
-		c.SetDeadline(time.Now().Add(5 * time.Second))
-		if _, err := io.WriteString(c, "HEAD / HTTP/1.0\n\n"); err != nil {
-			t.Fatal(err)
-		}
-		if _, err := c.Read(make([]byte, 1)); err != nil {
-			t.Fatal(err)
-		}
-		c.Close()
-	}
-}
-
 func TestConnCloseBreakingWrite(t *testing.T) {
 	ln := newLocalListener(t)
 	defer ln.Close()

libgo/go/debug/elf/file.go

@@ -171,6 +171,11 @@ type Symbol struct {
 	Info, Other byte
 	Section     SectionIndex
 	Value, Size uint64
+
+	// Version and Library are present only for the dynamic symbol
+	// table.
+	Version string
+	Library string
 }
 
 /*
@@ -1321,12 +1326,23 @@ func (f *File) Symbols() ([]Symbol, error) {
 // DynamicSymbols returns the dynamic symbol table for f. The symbols
 // will be listed in the order they appear in f.
 //
+// If f has a symbol version table, the returned Symbols will have
+// initialized Version and Library fields.
+//
 // For compatibility with Symbols, DynamicSymbols omits the null symbol at index 0.
 // After retrieving the symbols as symtab, an externally supplied index x
 // corresponds to symtab[x-1], not symtab[x].
 func (f *File) DynamicSymbols() ([]Symbol, error) {
-	sym, _, err := f.getSymbols(SHT_DYNSYM)
-	return sym, err
+	sym, str, err := f.getSymbols(SHT_DYNSYM)
+	if err != nil {
+		return nil, err
+	}
+	if f.gnuVersionInit(str) {
+		for i := range sym {
+			sym[i].Library, sym[i].Version = f.gnuVersion(i)
+		}
+	}
+	return sym, nil
 }
 
 type ImportedSymbol struct {
@@ -1349,7 +1365,8 @@ func (f *File) ImportedSymbols() ([]ImportedSymbol, error) {
 	for i, s := range sym {
 		if ST_BIND(s.Info) == STB_GLOBAL && s.Section == SHN_UNDEF {
 			all = append(all, ImportedSymbol{Name: s.Name})
-			f.gnuVersion(i, &all[len(all)-1])
+			sym := &all[len(all)-1]
+			sym.Library, sym.Version = f.gnuVersion(i)
 		}
 	}
 	return all, nil
@@ -1362,11 +1379,16 @@ type verneed struct {
 
 // gnuVersionInit parses the GNU version tables
 // for use by calls to gnuVersion.
-func (f *File) gnuVersionInit(str []byte) {
+func (f *File) gnuVersionInit(str []byte) bool {
+	if f.gnuNeed != nil {
+		// Already initialized
+		return true
+	}
+
 	// Accumulate verneed information.
 	vn := f.SectionByType(SHT_GNU_VERNEED)
 	if vn == nil {
-		return
+		return false
 	}
 	d, _ := vn.Data()
 
@@ -1421,17 +1443,18 @@ func (f *File) gnuVersionInit(str []byte) {
 	// Versym parallels symbol table, indexing into verneed.
 	vs := f.SectionByType(SHT_GNU_VERSYM)
 	if vs == nil {
-		return
+		return false
 	}
 	d, _ = vs.Data()
 
 	f.gnuNeed = need
 	f.gnuVersym = d
+	return true
 }
 
 // gnuVersion adds Library and Version information to sym,
 // which came from offset i of the symbol table.
-func (f *File) gnuVersion(i int, sym *ImportedSymbol) {
+func (f *File) gnuVersion(i int) (library string, version string) {
 	// Each entry is two bytes.
 	i = (i + 1) * 2
 	if i >= len(f.gnuVersym) {
@@ -1442,8 +1465,7 @@ func (f *File) gnuVersion(i int, sym *ImportedSymbol) {
 		return
 	}
 	n := &f.gnuNeed[j]
-	sym.Library = n.File
-	sym.Version = n.Name
+	return n.File, n.Name
 }
 
 // ImportedLibraries returns the names of all libraries

libgo/go/debug/elf/symbols_test.go

@@ -819,6 +819,8 @@ var dynamicSymbolsGolden = map[string][]Symbol{
 			Section: 0x0,
 			Value:   0x0,
 			Size:    0x18C,
+			Version: "GLIBC_2.2.5",
+			Library: "libc.so.6",
 		},
 		Symbol{
 			Name:    "__libc_start_main",
@@ -827,6 +829,8 @@ var dynamicSymbolsGolden = map[string][]Symbol{
 			Section: 0x0,
 			Value:   0x0,
 			Size:    0x1C2,
+			Version: "GLIBC_2.2.5",
+			Library: "libc.so.6",
 		},
 	},
 	"testdata/go-relocation-test-clang-x86.obj": {},