src/runtime/runtime-gdb_test.go - go - Git at Google

 // Copyright 2015 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 runtime_test

 import (
 	"bytes"
 	"fmt"
 	"go/build"
 	"internal/testenv"
 	"io/ioutil"
 	"os"
 	"os/exec"
 	"path/filepath"
 	"regexp"
 	"runtime"
 	"strconv"
 	"strings"
 	"testing"
 )

 func checkGdbEnvironment(t *testing.T) {
 	testenv.MustHaveGoBuild(t)
 	if runtime.GOOS == "darwin" {
 		t.Skip("gdb does not work on darwin")
 	}
 	if runtime.GOOS == "linux" && runtime.GOARCH == "ppc64" {
 		t.Skip("skipping gdb tests on linux/ppc64; see golang.org/issue/17366")
 	}
 	if final := os.Getenv("GOROOT_FINAL"); final != "" && runtime.GOROOT() != final {
 		t.Skip("gdb test can fail with GOROOT_FINAL pending")
 	}
 }

 func checkGdbVersion(t *testing.T) {
 	// Issue 11214 reports various failures with older versions of gdb.
 	out, err := exec.Command("gdb", "--version").CombinedOutput()
 	if err != nil {
 		t.Skipf("skipping: error executing gdb: %v", err)
 	}
 	re := regexp.MustCompile(`([0-9]+)\.([0-9]+)`)
 	matches := re.FindSubmatch(out)
 	if len(matches) < 3 {
 		t.Skipf("skipping: can't determine gdb version from\n%s\n", out)
 	}
 	major, err1 := strconv.Atoi(string(matches[1]))
 	minor, err2 := strconv.Atoi(string(matches[2]))
 	if err1 != nil || err2 != nil {
 		t.Skipf("skipping: can't determine gdb version: %v, %v", err1, err2)
 	}
 	if major < 7 || (major == 7 && minor < 7) {
 		t.Skipf("skipping: gdb version %d.%d too old", major, minor)
 	}
 	t.Logf("gdb version %d.%d", major, minor)
 }

 func checkGdbPython(t *testing.T) {
 	cmd := exec.Command("gdb", "-nx", "-q", "--batch", "-iex", "python import sys; print('go gdb python support')")
 	out, err := cmd.CombinedOutput()

 	if err != nil {
 		t.Skipf("skipping due to issue running gdb: %v", err)
 	}
 	if string(out) != "go gdb python support\n" {
 		t.Skipf("skipping due to lack of python gdb support: %s", out)
 	}
 }

 const helloSource = `
 import "fmt"
 var gslice []string
 func main() {
 	mapvar := make(map[string]string,5)
 	mapvar["abc"] = "def"
 	mapvar["ghi"] = "jkl"
 	strvar := "abc"
 	ptrvar := &strvar
 	slicevar := make([]string, 0, 16)
 	slicevar = append(slicevar, mapvar["abc"])
 	fmt.Println("hi") // line 12
 	_ = ptrvar
 	gslice = slicevar
 }
 `

 func TestGdbPython(t *testing.T) {
 	testGdbPython(t, false)
 }

 func TestGdbPythonCgo(t *testing.T) {
 	testGdbPython(t, true)
 }

 func testGdbPython(t *testing.T, cgo bool) {
 	if runtime.GOARCH == "mips64" {
 		testenv.SkipFlaky(t, 18173)
 	}
 	if cgo && !build.Default.CgoEnabled {
 		t.Skip("skipping because cgo is not enabled")
 	}

 	t.Parallel()
 	checkGdbEnvironment(t)
 	checkGdbVersion(t)
 	checkGdbPython(t)

 	dir, err := ioutil.TempDir("", "go-build")
 	if err != nil {
 		t.Fatalf("failed to create temp directory: %v", err)
 	}
 	defer os.RemoveAll(dir)

 	var buf bytes.Buffer
 	buf.WriteString("package main\n")
 	if cgo {
 		buf.WriteString(`import "C"` + "\n")
 	}
 	buf.WriteString(helloSource)

 	src := filepath.Join(dir, "main.go")
 	err = ioutil.WriteFile(src, buf.Bytes(), 0644)
 	if err != nil {
 		t.Fatalf("failed to create file: %v", err)
 	}

 	cmd := exec.Command(testenv.GoToolPath(t), "build", "-o", "a.exe")
 	cmd.Dir = dir
 	out, err := testEnv(cmd).CombinedOutput()
 	if err != nil {
 		t.Fatalf("building source %v\n%s", err, out)
 	}

 	args := []string{"-nx", "-q", "--batch", "-iex",
 		fmt.Sprintf("add-auto-load-safe-path %s/src/runtime", runtime.GOROOT()),
 		"-ex", "set startup-with-shell off",
 		"-ex", "info auto-load python-scripts",
 		"-ex", "set python print-stack full",
 		"-ex", "br fmt.Println",
 		"-ex", "run",
 		"-ex", "echo BEGIN info goroutines\n",
 		"-ex", "info goroutines",
 		"-ex", "echo END\n",
 		"-ex", "up", // up from fmt.Println to main
 		"-ex", "echo BEGIN print mapvar\n",
 		"-ex", "print mapvar",
 		"-ex", "echo END\n",
 		"-ex", "echo BEGIN print strvar\n",
 		"-ex", "print strvar",
 		"-ex", "echo END\n",
 		"-ex", "echo BEGIN info locals\n",
 		"-ex", "info locals",
 		"-ex", "echo END\n",
 		"-ex", "down", // back to fmt.Println (goroutine 2 below only works at bottom of stack.  TODO: fix that)
 		"-ex", "echo BEGIN goroutine 2 bt\n",
 		"-ex", "goroutine 2 bt",
 		"-ex", "echo END\n",
 		filepath.Join(dir, "a.exe"),
 	}
 	got, _ := exec.Command("gdb", args...).CombinedOutput()

 	firstLine := bytes.SplitN(got, []byte("\n"), 2)[0]
 	if string(firstLine) != "Loading Go Runtime support." {
 		// This can happen when using all.bash with
 		// GOROOT_FINAL set, because the tests are run before
 		// the final installation of the files.
 		cmd := exec.Command(testenv.GoToolPath(t), "env", "GOROOT")
 		cmd.Env = []string{}
 		out, err := cmd.CombinedOutput()
 		if err != nil && bytes.Contains(out, []byte("cannot find GOROOT")) {
 			t.Skipf("skipping because GOROOT=%s does not exist", runtime.GOROOT())
 		}

 		_, file, _, _ := runtime.Caller(1)

 		t.Logf("package testing source file: %s", file)
 		t.Fatalf("failed to load Go runtime support: %s\n%s", firstLine, got)
 	}

 	// Extract named BEGIN...END blocks from output
 	partRe := regexp.MustCompile(`(?ms)^BEGIN ([^\n]*)\n(.*?)\nEND`)
 	blocks := map[string]string{}
 	for _, subs := range partRe.FindAllSubmatch(got, -1) {
 		blocks[string(subs[1])] = string(subs[2])
 	}

 	infoGoroutinesRe := regexp.MustCompile(`\*\s+\d+\s+running\s+`)
 	if bl := blocks["info goroutines"]; !infoGoroutinesRe.MatchString(bl) {
 		t.Fatalf("info goroutines failed: %s", bl)
 	}

 	printMapvarRe := regexp.MustCompile(`\Q = map[string]string = {["abc"] = "def", ["ghi"] = "jkl"}\E$`)
 	if bl := blocks["print mapvar"]; !printMapvarRe.MatchString(bl) {
 		t.Fatalf("print mapvar failed: %s", bl)
 	}

 	strVarRe := regexp.MustCompile(`\Q = "abc"\E$`)
 	if bl := blocks["print strvar"]; !strVarRe.MatchString(bl) {
 		t.Fatalf("print strvar failed: %s", bl)
 	}

 	// Issue 16338: ssa decompose phase can split a structure into
 	// a collection of scalar vars holding the fields. In such cases
 	// the DWARF variable location expression should be of the
 	// form "var.field" and not just "field".
 	infoLocalsRe := regexp.MustCompile(`^slicevar.len = `)
 	if bl := blocks["info locals"]; !infoLocalsRe.MatchString(bl) {
 		t.Fatalf("info locals failed: %s", bl)
 	}

 	btGoroutineRe := regexp.MustCompile(`^#0\s+runtime.+at`)
 	if bl := blocks["goroutine 2 bt"]; !btGoroutineRe.MatchString(bl) {
 		t.Fatalf("goroutine 2 bt failed: %s", bl)
 	}
 }

 const backtraceSource = `
 package main

 //go:noinline
 func aaa() bool { return bbb() }

 //go:noinline
 func bbb() bool { return ccc() }

 //go:noinline
 func ccc() bool { return ddd() }

 //go:noinline
 func ddd() bool { return f() }

 //go:noinline
 func eee() bool { return true }

 var f = eee

 func main() {
 	_ = aaa()
 }
 `

 // TestGdbBacktrace tests that gdb can unwind the stack correctly
 // using only the DWARF debug info.
 func TestGdbBacktrace(t *testing.T) {
 	if runtime.GOOS == "netbsd" {
 		testenv.SkipFlaky(t, 15603)
 	}
 	if runtime.GOARCH == "mips64" {
 		testenv.SkipFlaky(t, 18173)
 	}

 	t.Parallel()
 	checkGdbEnvironment(t)
 	checkGdbVersion(t)

 	dir, err := ioutil.TempDir("", "go-build")
 	if err != nil {
 		t.Fatalf("failed to create temp directory: %v", err)
 	}
 	defer os.RemoveAll(dir)

 	// Build the source code.
 	src := filepath.Join(dir, "main.go")
 	err = ioutil.WriteFile(src, []byte(backtraceSource), 0644)
 	if err != nil {
 		t.Fatalf("failed to create file: %v", err)
 	}
 	cmd := exec.Command(testenv.GoToolPath(t), "build", "-o", "a.exe")
 	cmd.Dir = dir
 	out, err := testEnv(cmd).CombinedOutput()
 	if err != nil {
 		t.Fatalf("building source %v\n%s", err, out)
 	}

 	// Execute gdb commands.
 	args := []string{"-nx", "-batch",
 		"-ex", "set startup-with-shell off",
 		"-ex", "break main.eee",
 		"-ex", "run",
 		"-ex", "backtrace",
 		"-ex", "continue",
 		filepath.Join(dir, "a.exe"),
 	}
 	got, _ := exec.Command("gdb", args...).CombinedOutput()

 	// Check that the backtrace matches the source code.
 	bt := []string{
 		"eee",
 		"ddd",
 		"ccc",
 		"bbb",
 		"aaa",
 		"main",
 	}
 	for i, name := range bt {
 		s := fmt.Sprintf("#%v.*main\\.%v", i, name)
 		re := regexp.MustCompile(s)
 		if found := re.Find(got) != nil; !found {
 			t.Errorf("could not find '%v' in backtrace", s)
 			t.Fatalf("gdb output:\n%v", string(got))
 		}
 	}
 }

 const autotmpTypeSource = `
 package main

 type astruct struct {
 	a, b int
 }

 func main() {
 	var iface interface{} = map[string]astruct{}
 	var iface2 interface{} = []astruct{}
 	println(iface, iface2)
 }
 `

 // TestGdbAutotmpTypes ensures that types of autotmp variables appear in .debug_info
 // See bug #17830.
 func TestGdbAutotmpTypes(t *testing.T) {
 	if runtime.GOARCH == "mips64" {
 		testenv.SkipFlaky(t, 18173)
 	}

 	t.Parallel()
 	checkGdbEnvironment(t)
 	checkGdbVersion(t)

 	dir, err := ioutil.TempDir("", "go-build")
 	if err != nil {
 		t.Fatalf("failed to create temp directory: %v", err)
 	}
 	defer os.RemoveAll(dir)

 	// Build the source code.
 	src := filepath.Join(dir, "main.go")
 	err = ioutil.WriteFile(src, []byte(autotmpTypeSource), 0644)
 	if err != nil {
 		t.Fatalf("failed to create file: %v", err)
 	}
 	cmd := exec.Command(testenv.GoToolPath(t), "build", "-gcflags=-N -l", "-o", "a.exe")
 	cmd.Dir = dir
 	out, err := testEnv(cmd).CombinedOutput()
 	if err != nil {
 		t.Fatalf("building source %v\n%s", err, out)
 	}

 	// Execute gdb commands.
 	args := []string{"-nx", "-batch",
 		"-ex", "set startup-with-shell off",
 		"-ex", "break main.main",
 		"-ex", "run",
 		"-ex", "step",
 		"-ex", "info types astruct",
 		filepath.Join(dir, "a.exe"),
 	}
 	got, _ := exec.Command("gdb", args...).CombinedOutput()

 	sgot := string(got)

 	// Check that the backtrace matches the source code.
 	types := []string{
 		"struct []main.astruct;",
 		"struct bucket<string,main.astruct>;",
 		"struct hash<string,main.astruct>;",
 		"struct main.astruct;",
 		"typedef struct hash<string,main.astruct> * map[string]main.astruct;",
 	}
 	for _, name := range types {
 		if !strings.Contains(sgot, name) {
 			t.Errorf("could not find %s in 'info typrs astruct' output", name)
 			t.Fatalf("gdb output:\n%v", sgot)
 		}
 	}
 }
	// Copyright 2015 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 runtime_test

	import (
	"bytes"
	"fmt"
	"go/build"
	"internal/testenv"
	"io/ioutil"
	"os"
	"os/exec"
	"path/filepath"
	"regexp"
	"runtime"
	"strconv"
	"strings"
	"testing"
	)

	func checkGdbEnvironment(t *testing.T) {
	testenv.MustHaveGoBuild(t)
	if runtime.GOOS == "darwin" {
	t.Skip("gdb does not work on darwin")
	}
	if runtime.GOOS == "linux" && runtime.GOARCH == "ppc64" {
	t.Skip("skipping gdb tests on linux/ppc64; see golang.org/issue/17366")
	}
	if final := os.Getenv("GOROOT_FINAL"); final != "" && runtime.GOROOT() != final {
	t.Skip("gdb test can fail with GOROOT_FINAL pending")
	}
	}

	func checkGdbVersion(t *testing.T) {
	// Issue 11214 reports various failures with older versions of gdb.
	out, err := exec.Command("gdb", "--version").CombinedOutput()
	if err != nil {
	t.Skipf("skipping: error executing gdb: %v", err)
	}
	re := regexp.MustCompile(`([0-9]+)\.([0-9]+)`)
	matches := re.FindSubmatch(out)
	if len(matches) < 3 {
	t.Skipf("skipping: can't determine gdb version from\n%s\n", out)
	}
	major, err1 := strconv.Atoi(string(matches[1]))
	minor, err2 := strconv.Atoi(string(matches[2]))
	if err1 != nil \|\| err2 != nil {
	t.Skipf("skipping: can't determine gdb version: %v, %v", err1, err2)
	}
	if major < 7 \|\| (major == 7 && minor < 7) {
	t.Skipf("skipping: gdb version %d.%d too old", major, minor)
	}
	t.Logf("gdb version %d.%d", major, minor)
	}

	func checkGdbPython(t *testing.T) {
	cmd := exec.Command("gdb", "-nx", "-q", "--batch", "-iex", "python import sys; print('go gdb python support')")
	out, err := cmd.CombinedOutput()

	if err != nil {
	t.Skipf("skipping due to issue running gdb: %v", err)
	}
	if string(out) != "go gdb python support\n" {
	t.Skipf("skipping due to lack of python gdb support: %s", out)
	}
	}

	const helloSource = `
	import "fmt"
	var gslice []string
	func main() {
	mapvar := make(map[string]string,5)
	mapvar["abc"] = "def"
	mapvar["ghi"] = "jkl"
	strvar := "abc"
	ptrvar := &strvar
	slicevar := make([]string, 0, 16)
	slicevar = append(slicevar, mapvar["abc"])
	fmt.Println("hi") // line 12
	_ = ptrvar
	gslice = slicevar
	}
	`

	func TestGdbPython(t *testing.T) {
	testGdbPython(t, false)
	}

	func TestGdbPythonCgo(t *testing.T) {
	testGdbPython(t, true)
	}

	func testGdbPython(t *testing.T, cgo bool) {
	if runtime.GOARCH == "mips64" {
	testenv.SkipFlaky(t, 18173)
	}
	if cgo && !build.Default.CgoEnabled {
	t.Skip("skipping because cgo is not enabled")
	}

	t.Parallel()
	checkGdbEnvironment(t)
	checkGdbVersion(t)
	checkGdbPython(t)

	dir, err := ioutil.TempDir("", "go-build")
	if err != nil {
	t.Fatalf("failed to create temp directory: %v", err)
	}
	defer os.RemoveAll(dir)

	var buf bytes.Buffer
	buf.WriteString("package main\n")
	if cgo {
	buf.WriteString(`import "C"` + "\n")
	}
	buf.WriteString(helloSource)

	src := filepath.Join(dir, "main.go")
	err = ioutil.WriteFile(src, buf.Bytes(), 0644)
	if err != nil {
	t.Fatalf("failed to create file: %v", err)
	}

	cmd := exec.Command(testenv.GoToolPath(t), "build", "-o", "a.exe")
	cmd.Dir = dir
	out, err := testEnv(cmd).CombinedOutput()
	if err != nil {
	t.Fatalf("building source %v\n%s", err, out)
	}

	args := []string{"-nx", "-q", "--batch", "-iex",
	fmt.Sprintf("add-auto-load-safe-path %s/src/runtime", runtime.GOROOT()),
	"-ex", "set startup-with-shell off",
	"-ex", "info auto-load python-scripts",
	"-ex", "set python print-stack full",
	"-ex", "br fmt.Println",
	"-ex", "run",
	"-ex", "echo BEGIN info goroutines\n",
	"-ex", "info goroutines",
	"-ex", "echo END\n",
	"-ex", "up", // up from fmt.Println to main
	"-ex", "echo BEGIN print mapvar\n",
	"-ex", "print mapvar",
	"-ex", "echo END\n",
	"-ex", "echo BEGIN print strvar\n",
	"-ex", "print strvar",
	"-ex", "echo END\n",
	"-ex", "echo BEGIN info locals\n",
	"-ex", "info locals",
	"-ex", "echo END\n",
	"-ex", "down", // back to fmt.Println (goroutine 2 below only works at bottom of stack. TODO: fix that)
	"-ex", "echo BEGIN goroutine 2 bt\n",
	"-ex", "goroutine 2 bt",
	"-ex", "echo END\n",
	filepath.Join(dir, "a.exe"),
	}
	got, _ := exec.Command("gdb", args...).CombinedOutput()

	firstLine := bytes.SplitN(got, []byte("\n"), 2)[0]
	if string(firstLine) != "Loading Go Runtime support." {
	// This can happen when using all.bash with
	// GOROOT_FINAL set, because the tests are run before
	// the final installation of the files.
	cmd := exec.Command(testenv.GoToolPath(t), "env", "GOROOT")
	cmd.Env = []string{}
	out, err := cmd.CombinedOutput()
	if err != nil && bytes.Contains(out, []byte("cannot find GOROOT")) {
	t.Skipf("skipping because GOROOT=%s does not exist", runtime.GOROOT())
	}

	_, file, _, _ := runtime.Caller(1)

	t.Logf("package testing source file: %s", file)
	t.Fatalf("failed to load Go runtime support: %s\n%s", firstLine, got)
	}

	// Extract named BEGIN...END blocks from output
	partRe := regexp.MustCompile(`(?ms)^BEGIN ([^\n])\n(.?)\nEND`)
	blocks := map[string]string{}
	for _, subs := range partRe.FindAllSubmatch(got, -1) {
	blocks[string(subs[1])] = string(subs[2])
	}

	infoGoroutinesRe := regexp.MustCompile(`\*\s+\d+\s+running\s+`)
	if bl := blocks["info goroutines"]; !infoGoroutinesRe.MatchString(bl) {
	t.Fatalf("info goroutines failed: %s", bl)
	}

	printMapvarRe := regexp.MustCompile(`\Q = map[string]string = {["abc"] = "def", ["ghi"] = "jkl"}\E$`)
	if bl := blocks["print mapvar"]; !printMapvarRe.MatchString(bl) {
	t.Fatalf("print mapvar failed: %s", bl)
	}

	strVarRe := regexp.MustCompile(`\Q = "abc"\E$`)
	if bl := blocks["print strvar"]; !strVarRe.MatchString(bl) {
	t.Fatalf("print strvar failed: %s", bl)
	}

	// Issue 16338: ssa decompose phase can split a structure into
	// a collection of scalar vars holding the fields. In such cases
	// the DWARF variable location expression should be of the
	// form "var.field" and not just "field".
	infoLocalsRe := regexp.MustCompile(`^slicevar.len = `)
	if bl := blocks["info locals"]; !infoLocalsRe.MatchString(bl) {
	t.Fatalf("info locals failed: %s", bl)
	}

	btGoroutineRe := regexp.MustCompile(`^#0\s+runtime.+at`)
	if bl := blocks["goroutine 2 bt"]; !btGoroutineRe.MatchString(bl) {
	t.Fatalf("goroutine 2 bt failed: %s", bl)
	}
	}

	const backtraceSource = `
	package main

	//go:noinline
	func aaa() bool { return bbb() }

	//go:noinline
	func bbb() bool { return ccc() }

	//go:noinline
	func ccc() bool { return ddd() }

	//go:noinline
	func ddd() bool { return f() }

	//go:noinline
	func eee() bool { return true }

	var f = eee

	func main() {
	_ = aaa()
	}
	`

	// TestGdbBacktrace tests that gdb can unwind the stack correctly
	// using only the DWARF debug info.
	func TestGdbBacktrace(t *testing.T) {
	if runtime.GOOS == "netbsd" {
	testenv.SkipFlaky(t, 15603)
	}
	if runtime.GOARCH == "mips64" {
	testenv.SkipFlaky(t, 18173)
	}

	t.Parallel()
	checkGdbEnvironment(t)
	checkGdbVersion(t)

	dir, err := ioutil.TempDir("", "go-build")
	if err != nil {
	t.Fatalf("failed to create temp directory: %v", err)
	}
	defer os.RemoveAll(dir)

	// Build the source code.
	src := filepath.Join(dir, "main.go")
	err = ioutil.WriteFile(src, []byte(backtraceSource), 0644)
	if err != nil {
	t.Fatalf("failed to create file: %v", err)
	}
	cmd := exec.Command(testenv.GoToolPath(t), "build", "-o", "a.exe")
	cmd.Dir = dir
	out, err := testEnv(cmd).CombinedOutput()
	if err != nil {
	t.Fatalf("building source %v\n%s", err, out)
	}

	// Execute gdb commands.
	args := []string{"-nx", "-batch",
	"-ex", "set startup-with-shell off",
	"-ex", "break main.eee",
	"-ex", "run",
	"-ex", "backtrace",
	"-ex", "continue",
	filepath.Join(dir, "a.exe"),
	}
	got, _ := exec.Command("gdb", args...).CombinedOutput()

	// Check that the backtrace matches the source code.
	bt := []string{
	"eee",
	"ddd",
	"ccc",
	"bbb",
	"aaa",
	"main",
	}
	for i, name := range bt {
	s := fmt.Sprintf("#%v.*main\\.%v", i, name)
	re := regexp.MustCompile(s)
	if found := re.Find(got) != nil; !found {
	t.Errorf("could not find '%v' in backtrace", s)
	t.Fatalf("gdb output:\n%v", string(got))
	}
	}
	}

	const autotmpTypeSource = `
	package main

	type astruct struct {
	a, b int
	}

	func main() {
	var iface interface{} = map[string]astruct{}
	var iface2 interface{} = []astruct{}
	println(iface, iface2)
	}
	`

	// TestGdbAutotmpTypes ensures that types of autotmp variables appear in .debug_info
	// See bug #17830.
	func TestGdbAutotmpTypes(t *testing.T) {
	if runtime.GOARCH == "mips64" {
	testenv.SkipFlaky(t, 18173)
	}

	t.Parallel()
	checkGdbEnvironment(t)
	checkGdbVersion(t)

	dir, err := ioutil.TempDir("", "go-build")
	if err != nil {
	t.Fatalf("failed to create temp directory: %v", err)
	}
	defer os.RemoveAll(dir)

	// Build the source code.
	src := filepath.Join(dir, "main.go")
	err = ioutil.WriteFile(src, []byte(autotmpTypeSource), 0644)
	if err != nil {
	t.Fatalf("failed to create file: %v", err)
	}
	cmd := exec.Command(testenv.GoToolPath(t), "build", "-gcflags=-N -l", "-o", "a.exe")
	cmd.Dir = dir
	out, err := testEnv(cmd).CombinedOutput()
	if err != nil {
	t.Fatalf("building source %v\n%s", err, out)
	}

	// Execute gdb commands.
	args := []string{"-nx", "-batch",
	"-ex", "set startup-with-shell off",
	"-ex", "break main.main",
	"-ex", "run",
	"-ex", "step",
	"-ex", "info types astruct",
	filepath.Join(dir, "a.exe"),
	}
	got, _ := exec.Command("gdb", args...).CombinedOutput()

	sgot := string(got)

	// Check that the backtrace matches the source code.
	types := []string{
	"struct []main.astruct;",
	"struct bucket<string,main.astruct>;",
	"struct hash<string,main.astruct>;",
	"struct main.astruct;",
	"typedef struct hash<string,main.astruct> * map[string]main.astruct;",
	}
	for _, name := range types {
	if !strings.Contains(sgot, name) {
	t.Errorf("could not find %s in 'info typrs astruct' output", name)
	t.Fatalf("gdb output:\n%v", sgot)
	}
	}
	}