cmd/go: run full 'go vet' during 'go test' for packages in GOROOT

Now that the main tree complies with 'go vet', enable all vet checks
during 'go test' in the main tree. This helps surface helpful errors
while developing, instead of having to wait for the misc-vet-vetall builder.

During 'go test', the additional vet checks are essentially free:
the vet invocations themselves take only 8 seconds total for the entire tree.

Also update buildall.bash (used by the misc-compile builders)
to run 'go vet std cmd' for each GOOS/GOARCH pair.
This is not as free, since in general it can require recompiling
packages with their tests included before invoking vet.
(That compilation was going on anyway in the 'go test' case.)

On my Mac laptop, ./buildall.bash freebsd used to take
68+16+17+18 = 119 seconds for make.bash and then
the builds of the three freebsd architectures.
Now it takes 68+16+23+17+23+18+24 = 189 seconds, 60% longer.
Some of this is spent doing unnecessary cgo work.
Still, this lets us shard the vet checks and match all.bash.

Fixes #20119.
For #31916.

Change-Id: I6b0c40bac47708a688463c7fca12c0fc23ab2751
Reviewed-on: https://go-review.googlesource.com/c/go/+/176439
Run-TryBot: Russ Cox <rsc@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>

src/buildall.bash

@@ -73,7 +73,11 @@ do
 		export GOARCH=386
 		export GO386=387
 	fi
-	if ! "$GOROOT/bin/go" build -a std cmd; then
+
+	# Build and vet everything.
+	# cmd/go/internal/work/exec.go enables the same vet flags during go test of std cmd
+	# and should be kept in sync with any vet flag changes here.
+	if ! "$GOROOT/bin/go" build std cmd || ! "$GOROOT/bin/go" vet -unsafeptr=false std cmd; then
 		failed=true
 		if $sete; then
 			exit 1

src/cmd/go/internal/load/test.go

@@ -192,6 +192,7 @@ func TestPackagesAndErrors(p *Package, cover *TestCover) (pmain, ptest, pxtest *
 				ImportPath: p.ImportPath + "_test",
 				Root:       p.Root,
 				Dir:        p.Dir,
+				Goroot:     p.Goroot,
 				GoFiles:    p.XTestGoFiles,
 				Imports:    p.XTestImports,
 				ForTest:    p.ImportPath,

src/cmd/go/internal/test/test.go

@@ -492,6 +492,9 @@ var (
 	testCacheExpire   time.Time                           // ignore cached test results before this time
 )
 
+// testVetExplicit records whether testVetFlags were set by an explicit -vet.
+var testVetExplicit = false
+
 // testVetFlags is the list of flags to pass to vet when invoked automatically during go test.
 var testVetFlags = []string{
 	// TODO(rsc): Decide which tests are enabled by default.
@@ -533,6 +536,7 @@ func runTest(cmd *base.Command, args []string) {
 
 	work.BuildInit()
 	work.VetFlags = testVetFlags
+	work.VetExplicit = testVetExplicit
 
 	pkgs = load.PackagesForBuild(pkgArgs)
 	if len(pkgs) == 0 {

src/cmd/go/internal/test/testflag.go

@@ -202,6 +202,7 @@ func testFlags(usage func(), args []string) (packageNames, passToTest []string)
 		}
 	}
 
+	testVetExplicit = testVetList != ""
 	if testVetList != "" && testVetList != "off" {
 		if strings.Contains(testVetList, "=") {
 			base.Fatalf("-vet argument cannot contain equal signs")

src/cmd/go/internal/work/exec.go

@@ -968,10 +968,13 @@ func buildVetConfig(a *Action, srcfiles []string) {
 // The caller is expected to set it (if needed) before executing any vet actions.
 var VetTool string
 
-// VetFlags are the flags to pass to vet.
+// VetFlags are the default flags to pass to vet.
 // The caller is expected to set them before executing any vet actions.
 var VetFlags []string
 
+// VetExplicit records whether the vet flags were set explicitly on the command line.
+var VetExplicit bool
+
 func (b *Builder) vet(a *Action) error {
 	// a.Deps[0] is the build of the package being vetted.
 	// a.Deps[1] is the build of the "fmt" package.
@@ -998,12 +1001,42 @@ func (b *Builder) vet(a *Action) error {
 	h := cache.NewHash("vet " + a.Package.ImportPath)
 	fmt.Fprintf(h, "vet %q\n", b.toolID("vet"))
 
+	vetFlags := VetFlags
+
+	// In GOROOT, we enable all the vet tests during 'go test',
+	// not just the high-confidence subset. This gets us extra
+	// checking for the standard library (at some compliance cost)
+	// and helps us gain experience about how well the checks
+	// work, to help decide which should be turned on by default.
+	// The command-line still wins.
+	//
+	// Note that this flag change applies even when running vet as
+	// a dependency of vetting a package outside std.
+	// (Otherwise we'd have to introduce a whole separate
+	// space of "vet fmt as a dependency of a std top-level vet"
+	// versus "vet fmt as a dependency of a non-std top-level vet".)
+	// This is OK as long as the packages that are farther down the
+	// dependency tree turn on *more* analysis, as here.
+	// (The unsafeptr check does not write any facts for use by
+	// later vet runs.)
+	if a.Package.Goroot && !VetExplicit {
+		// Note that $GOROOT/src/buildall.bash
+		// does the same for the misc-compile trybots
+		// and should be updated if these flags are
+		// changed here.
+		//
+		// There's too much unsafe.Pointer code
+		// that vet doesn't like in low-level packages
+		// like runtime, sync, and reflect.
+		vetFlags = []string{"-unsafeptr=false"}
+	}
+
 	// Note: We could decide that vet should compute export data for
 	// all analyses, in which case we don't need to include the flags here.
 	// But that would mean that if an analysis causes problems like
 	// unexpected crashes there would be no way to turn it off.
 	// It seems better to let the flags disable export analysis too.
-	fmt.Fprintf(h, "vetflags %q\n", VetFlags)
+	fmt.Fprintf(h, "vetflags %q\n", vetFlags)
 
 	fmt.Fprintf(h, "pkg %q\n", a.Deps[0].actionID)
 	for _, a1 := range a.Deps {
@@ -1023,26 +1056,6 @@ func (b *Builder) vet(a *Action) error {
 		}
 	}
 
-	// TODO(adonovan): delete this when we use the new vet printf checker.
-	// https://github.com/golang/go/issues/28756
-	if vcfg.ImportMap["fmt"] == "" {
-		a1 := a.Deps[1]
-		vcfg.ImportMap["fmt"] = "fmt"
-		if a1.built != "" {
-			vcfg.PackageFile["fmt"] = a1.built
-		}
-		vcfg.Standard["fmt"] = true
-	}
-
-	// During go test, ignore type-checking failures during vet.
-	// We only run vet if the compilation has succeeded,
-	// so at least for now assume the bug is in vet.
-	// We know of at least #18395.
-	// TODO(rsc,gri): Try to remove this for Go 1.11.
-	//
-	// Disabled 2018-04-20. Let's see if we can do without it.
-	// vcfg.SucceedOnTypecheckFailure = cfg.CmdName == "test"
-
 	js, err := json.MarshalIndent(vcfg, "", "\t")
 	if err != nil {
 		return fmt.Errorf("internal error marshaling vet config: %v", err)
@@ -1062,7 +1075,7 @@ func (b *Builder) vet(a *Action) error {
 	if tool == "" {
 		tool = base.Tool("vet")
 	}
-	runErr := b.run(a, p.Dir, p.ImportPath, env, cfg.BuildToolexec, tool, VetFlags, a.Objdir+"vet.cfg")
+	runErr := b.run(a, p.Dir, p.ImportPath, env, cfg.BuildToolexec, tool, vetFlags, a.Objdir+"vet.cfg")
 
 	// If vet wrote export data, save it for input to future vets.
 	if f, err := os.Open(vcfg.VetxOutput); err == nil {