cmd/go: disable tests when GOOS/GOARCH != GOHOSTARCH/GOHOSTARCH

The whole GOROOT/pkg tree is installed using the GOHOSTOS/GOHOSTARCH
toolchain (installed in GOROOT/pkg/tool/GOHOSTOS_GOHOSTARCH).
The testgo.exe we run during the cmd/go test will be built
for GOOS/GOARCH, which means it will use the GOOS/GOARCH toolchain
(installed in GOROOT/pkg/tool/GOOS_GOARCH).

If these are not the same toolchain, then the entire standard library
will look out of date to testgo.exe (the compilers in those two different
tool directories are built for different architectures and have different
buid IDs), which will cause many tests to do unnecessary rebuilds
and some tests to attempt to overwrite the installed standard library,
which will in turn make it look out of date to whatever runs after the
cmd/go test exits.

Bail out entirely in this case instead of destroying the world.

The changes outside TestMain are checks that might have caught
this a bit earlier and made it much less confusing to debug.

Fixes #22709.
Fixes #22965.

Change-Id: Ibf28fa19e29a1f1b8f17875f446d3474dd04a924
Reviewed-on: https://go-review.googlesource.com/81516
Run-TryBot: Russ Cox <rsc@golang.org>
Reviewed-by: Ian Lance Taylor <iant@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>

src/cmd/go/go_test.go

@@ -103,18 +103,42 @@ func TestMain(m *testing.M) {
 			fmt.Fprintln(os.Stderr, err)
 			os.Exit(2)
 		}
-		out, err := exec.Command(gotool, args...).CombinedOutput()
-		if err != nil {
-			fmt.Fprintf(os.Stderr, "building testgo failed: %v\n%s", err, out)
-			os.Exit(2)
+
+		goEnv := func(name string) string {
+			out, err := exec.Command(gotool, "env", name).CombinedOutput()
+			if err != nil {
+				fmt.Fprintf(os.Stderr, "go env %s: %v\n%s", name, err, out)
+				os.Exit(2)
+			}
+			return strings.TrimSpace(string(out))
+		}
+		testGOROOT = goEnv("GOROOT")
+
+		// The whole GOROOT/pkg tree was installed using the GOHOSTOS/GOHOSTARCH
+		// toolchain (installed in GOROOT/pkg/tool/GOHOSTOS_GOHOSTARCH).
+		// The testgo.exe we are about to create will be built for GOOS/GOARCH,
+		// which means it will use the GOOS/GOARCH toolchain
+		// (installed in GOROOT/pkg/tool/GOOS_GOARCH).
+		// If these are not the same toolchain, then the entire standard library
+		// will look out of date (the compilers in those two different tool directories
+		// are built for different architectures and have different buid IDs),
+		// which will cause many tests to do unnecessary rebuilds and some
+		// tests to attempt to overwrite the installed standard library.
+		// Bail out entirely in this case.
+		hostGOOS := goEnv("GOHOSTOS")
+		hostGOARCH := goEnv("GOHOSTARCH")
+		if hostGOOS != runtime.GOOS || hostGOARCH != runtime.GOARCH {
+			fmt.Fprintf(os.Stderr, "testing: warning: no tests to run\n") // magic string for cmd/go
+			fmt.Printf("cmd/go test is not compatible with GOOS/GOARCH != GOHOSTOS/GOHOSTARCH (%s/%s != %s/%s)\n", runtime.GOOS, runtime.GOARCH, hostGOOS, hostGOARCH)
+			fmt.Printf("SKIP\n")
+			return
 		}
 
-		out, err = exec.Command(gotool, "env", "GOROOT").CombinedOutput()
+		out, err := exec.Command(gotool, args...).CombinedOutput()
 		if err != nil {
-			fmt.Fprintf(os.Stderr, "could not find testing GOROOT: %v\n%s", err, out)
+			fmt.Fprintf(os.Stderr, "building testgo failed: %v\n%s", err, out)
 			os.Exit(2)
 		}
-		testGOROOT = strings.TrimSpace(string(out))
 
 		out, err = exec.Command(gotool, "env", "CC").CombinedOutput()
 		if err != nil {
@@ -1449,6 +1473,10 @@ func TestRelativeImportsGoTest(t *testing.T) {
 func TestRelativeImportsGoTestDashI(t *testing.T) {
 	tg := testgo(t)
 	defer tg.cleanup()
+
+	// don't let test -i overwrite runtime
+	tg.wantNotStale("runtime", "", "must be non-stale before test -i")
+
 	tg.run("test", "-i", "./testdata/testimport")
 }
 
@@ -1573,7 +1601,9 @@ func TestPackageNotStaleWithTrailingSlash(t *testing.T) {
 	defer tg.cleanup()
 
 	// Make sure the packages below are not stale.
-	tg.run("install", "runtime", "os", "io")
+	tg.wantNotStale("runtime", "", "must be non-stale before test runs")
+	tg.wantNotStale("os", "", "must be non-stale before test runs")
+	tg.wantNotStale("io", "", "must be non-stale before test runs")
 
 	goroot := runtime.GOROOT()
 	tg.setenv("GOROOT", goroot+"/")
@@ -2078,6 +2108,10 @@ func TestGoTestDashIDashOWritesBinary(t *testing.T) {
 	defer tg.cleanup()
 	tg.parallel()
 	tg.makeTempdir()
+
+	// don't let test -i overwrite runtime
+	tg.wantNotStale("runtime", "", "must be non-stale before test -i")
+
 	tg.run("test", "-v", "-i", "-o", tg.path("myerrors.test"+exeSuffix), "errors")
 	tg.grepBothNot("PASS|FAIL", "test should not have run")
 	tg.wantExecutable(tg.path("myerrors.test"+exeSuffix), "go test -o myerrors.test did not create myerrors.test")
@@ -2888,6 +2922,9 @@ func TestBuildDashIInstallsDependencies(t *testing.T) {
 		func F() { foo.F() }`)
 	tg.setenv("GOPATH", tg.path("."))
 
+	// don't let build -i overwrite runtime
+	tg.wantNotStale("runtime", "", "must be non-stale before build -i")
+
 	checkbar := func(desc string) {
 		tg.run("build", "-v", "-i", "x/y/bar")
 		tg.grepBoth("x/y/foo", "first build -i "+desc+" did not build x/y/foo")
@@ -3067,7 +3104,6 @@ func TestGoVetWithExternalTests(t *testing.T) {
 	tg := testgo(t)
 	defer tg.cleanup()
 	tg.makeTempdir()
-	tg.run("install", "cmd/vet")
 	tg.setenv("GOPATH", filepath.Join(tg.pwd(), "testdata"))
 	tg.runFail("vet", "vetpkg")
 	tg.grepBoth("Printf", "go vet vetpkg did not find missing argument for Printf")
@@ -3077,7 +3113,6 @@ func TestGoVetWithTags(t *testing.T) {
 	tg := testgo(t)
 	defer tg.cleanup()
 	tg.makeTempdir()
-	tg.run("install", "cmd/vet")
 	tg.setenv("GOPATH", filepath.Join(tg.pwd(), "testdata"))
 	tg.runFail("vet", "-tags", "tagtest", "vetpkg")
 	tg.grepBoth(`c\.go.*Printf`, "go vet vetpkg did not run scan tagged file")
@@ -3087,7 +3122,6 @@ func TestGoVetWithFlagsOn(t *testing.T) {
 	tg := testgo(t)
 	defer tg.cleanup()
 	tg.makeTempdir()
-	tg.run("install", "cmd/vet")
 	tg.setenv("GOPATH", filepath.Join(tg.pwd(), "testdata"))
 	tg.runFail("vet", "-printf", "vetpkg")
 	tg.grepBoth("Printf", "go vet -printf vetpkg did not find missing argument for Printf")
@@ -3097,7 +3131,6 @@ func TestGoVetWithFlagsOff(t *testing.T) {
 	tg := testgo(t)
 	defer tg.cleanup()
 	tg.makeTempdir()
-	tg.run("install", "cmd/vet")
 	tg.setenv("GOPATH", filepath.Join(tg.pwd(), "testdata"))
 	tg.run("vet", "-printf=false", "vetpkg")
 }
@@ -4321,9 +4354,7 @@ func TestBuildTagsNoComma(t *testing.T) {
 	defer tg.cleanup()
 	tg.makeTempdir()
 	tg.setenv("GOPATH", tg.path("go"))
-	tg.run("install", "-tags", "tag1 tag2", "math")
-	tg.runFail("install", "-tags", "tag1,tag2", "math")
-	tg.grepBoth("space-separated list contains comma", "-tags with a comma-separated list didn't error")
+	tg.run("build", "-tags", "tag1 tag2", "math")
 	tg.runFail("build", "-tags", "tag1,tag2", "math")
 	tg.grepBoth("space-separated list contains comma", "-tags with a comma-separated list didn't error")
 }
@@ -5172,6 +5203,9 @@ func TestInstallDeps(t *testing.T) {
 	tg.mustExist(p2)
 	tg.mustNotExist(p1)
 
+	// don't let install -i overwrite runtime
+	tg.wantNotStale("runtime", "", "must be non-stale before install -i")
+
 	tg.run("install", "-i", "main1")
 	tg.mustExist(p1)
 	tg.must(os.Remove(p1))