test: avoid writing temporary files to GOROOT

Updates #28387
Fixes #35619

Change-Id: I162f3427b7901c117e3f3e403df7edec7c529bd1
Reviewed-on: https://go-review.googlesource.com/c/go/+/207352
Run-TryBot: Bryan C. Mills <bcmills@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>

src/cmd/dist/test.go

@@ -1361,17 +1361,21 @@ var runtest struct {
 
 func (t *tester) testDirTest(dt *distTest, shard, shards int) error {
 	runtest.Do(func() {
-		const exe = "runtest.exe" // named exe for Windows, but harmless elsewhere
-		cmd := t.dirCmd("test", "go", "build", "-o", exe, "run.go")
-		cmd.Env = append(os.Environ(), "GOOS="+gohostos, "GOARCH="+gohostarch)
-		runtest.exe = filepath.Join(cmd.Dir, exe)
-		if err := cmd.Run(); err != nil {
+		f, err := ioutil.TempFile("", "runtest-*.exe") // named exe for Windows, but harmless elsewhere
+		if err != nil {
 			runtest.err = err
 			return
 		}
+		f.Close()
+
+		runtest.exe = f.Name()
 		xatexit(func() {
 			os.Remove(runtest.exe)
 		})
+
+		cmd := t.dirCmd("test", "go", "build", "-o", runtest.exe, "run.go")
+		cmd.Env = append(os.Environ(), "GOOS="+gohostos, "GOARCH="+gohostarch)
+		runtest.err = cmd.Run()
 	})
 	if runtest.err != nil {
 		return runtest.err

test/fixedbugs/bug302.go

@@ -9,22 +9,34 @@ package main
 
 import (
 	"fmt"
+	"io/ioutil"
 	"os"
 	"os/exec"
 	"path/filepath"
 )
 
+var tmpDir string
+
 func main() {
-	run("go", "tool", "compile", filepath.Join("fixedbugs", "bug302.dir", "p.go"))
+	fb, err := filepath.Abs("fixedbugs")
+	if err == nil {
+		tmpDir, err = ioutil.TempDir("", "bug302")
+	}
+	if err != nil {
+		fmt.Println(err)
+		os.Exit(1)
+	}
+	defer os.RemoveAll(tmpDir)
+
+	run("go", "tool", "compile", filepath.Join(fb, "bug302.dir", "p.go"))
 	run("go", "tool", "pack", "grc", "pp.a", "p.o")
-	run("go", "tool", "compile", "-I", ".", filepath.Join("fixedbugs", "bug302.dir", "main.go"))
-	os.Remove("p.o")
-	os.Remove("pp.a")
-	os.Remove("main.o")
+	run("go", "tool", "compile", "-I", ".", filepath.Join(fb, "bug302.dir", "main.go"))
 }
 
 func run(cmd string, args ...string) {
-	out, err := exec.Command(cmd, args...).CombinedOutput()
+	c := exec.Command(cmd, args...)
+	c.Dir = tmpDir
+	out, err := c.CombinedOutput()
 	if err != nil {
 		fmt.Println(string(out))
 		fmt.Println(err)

test/fixedbugs/bug369.go

@@ -11,6 +11,7 @@ package main
 
 import (
 	"fmt"
+	"io/ioutil"
 	"os"
 	"os/exec"
 	"path/filepath"
@@ -20,16 +21,19 @@ func main() {
 	err := os.Chdir(filepath.Join(".", "fixedbugs", "bug369.dir"))
 	check(err)
 
-	run("go", "tool", "compile", "-N", "-o", "slow.o", "pkg.go")
-	run("go", "tool", "compile", "-o", "fast.o", "pkg.go")
-	run("go", "tool", "compile", "-o", "main.o", "main.go")
-	run("go", "tool", "link", "-o", "a.exe", "main.o")
-	run("." + string(filepath.Separator) + "a.exe")
+	tmpDir, err := ioutil.TempDir("", "bug369")
+	check(err)
+	defer os.RemoveAll(tmpDir)
 
-	os.Remove("slow.o")
-	os.Remove("fast.o")
-	os.Remove("main.o")
-	os.Remove("a.exe")
+	tmp := func(name string) string {
+		return filepath.Join(tmpDir, name)
+	}
+
+	run("go", "tool", "compile", "-N", "-o", tmp("slow.o"), "pkg.go")
+	run("go", "tool", "compile", "-o", tmp("fast.o"), "pkg.go")
+	run("go", "tool", "compile", "-D", tmpDir, "-o", tmp("main.o"), "main.go")
+	run("go", "tool", "link", "-o", tmp("a.exe"), tmp("main.o"))
+	run(tmp("a.exe"))
 }
 
 func run(name string, args ...string) {

test/fixedbugs/issue9355.go

@@ -23,8 +23,7 @@ func main() {
 	err := os.Chdir(filepath.Join("fixedbugs", "issue9355.dir"))
 	check(err)
 
-	out := run("go", "tool", "compile", "-S", "a.go")
-	os.Remove("a.o")
+	out := run("go", "tool", "compile", "-o", os.DevNull, "-S", "a.go")
 
 	// 6g/8g print the offset as dec, but 5g/9g print the offset as hex.
 	patterns := []string{

test/linkmain_run.go

@@ -11,21 +11,21 @@ package main
 
 import (
 	"fmt"
+	"io/ioutil"
 	"os"
 	"os/exec"
+	"path/filepath"
 	"strings"
 )
 
+var tmpDir string
+
 func cleanup() {
-	os.Remove("linkmain.o")
-	os.Remove("linkmain.a")
-	os.Remove("linkmain1.o")
-	os.Remove("linkmain1.a")
-	os.Remove("linkmain.exe")
+	os.RemoveAll(tmpDir)
 }
 
-func run(cmdline string) {
-	args := strings.Fields(cmdline)
+func run(cmdline ...string) {
+	args := strings.Fields(strings.Join(cmdline, " "))
 	cmd := exec.Command(args[0], args[1:]...)
 	out, err := cmd.CombinedOutput()
 	if err != nil {
@@ -37,8 +37,8 @@ func run(cmdline string) {
 	}
 }
 
-func runFail(cmdline string) {
-	args := strings.Fields(cmdline)
+func runFail(cmdline ...string) {
+	args := strings.Fields(strings.Join(cmdline, " "))
 	cmd := exec.Command(args[0], args[1:]...)
 	out, err := cmd.CombinedOutput()
 	if err == nil {
@@ -51,16 +51,26 @@ func runFail(cmdline string) {
 }
 
 func main() {
+	var err error
+	tmpDir, err = ioutil.TempDir("", "")
+	if err != nil {
+		fmt.Println(err)
+		os.Exit(1)
+	}
+	tmp := func(name string) string {
+		return filepath.Join(tmpDir, name)
+	}
+
 	// helloworld.go is package main
-	run("go tool compile -o linkmain.o helloworld.go")
-	run("go tool compile -pack -o linkmain.a helloworld.go")
-	run("go tool link -o linkmain.exe linkmain.o")
-	run("go tool link -o linkmain.exe linkmain.a")
+	run("go tool compile -o", tmp("linkmain.o"), "helloworld.go")
+	run("go tool compile -pack -o", tmp("linkmain.a"), "helloworld.go")
+	run("go tool link -o", tmp("linkmain.exe"), tmp("linkmain.o"))
+	run("go tool link -o", tmp("linkmain.exe"), tmp("linkmain.a"))
 
 	// linkmain.go is not
-	run("go tool compile -o linkmain1.o linkmain.go")
-	run("go tool compile -pack -o linkmain1.a linkmain.go")
-	runFail("go tool link -o linkmain.exe linkmain1.o")
-	runFail("go tool link -o linkmain.exe linkmain1.a")
+	run("go tool compile -o", tmp("linkmain1.o"), "linkmain.go")
+	run("go tool compile -pack -o", tmp("linkmain1.a"), "linkmain.go")
+	runFail("go tool link -o", tmp("linkmain.exe"), tmp("linkmain1.o"))
+	runFail("go tool link -o", tmp("linkmain.exe"), tmp("linkmain1.a"))
 	cleanup()
 }

test/sinit_run.go

@@ -17,15 +17,18 @@ import (
 )
 
 func main() {
-	cmd := exec.Command("go", "tool", "compile", "-S", "sinit.go")
+	cmd := exec.Command("go", "tool", "compile", "-o", os.DevNull, "-S", "sinit.go")
 	out, err := cmd.CombinedOutput()
 	if err != nil {
 		fmt.Println(string(out))
 		fmt.Println(err)
 		os.Exit(1)
 	}
-	os.Remove("sinit.o")
 
+	if len(bytes.TrimSpace(out)) == 0 {
+		fmt.Println("'go tool compile -S sinit.go' printed no output")
+		os.Exit(1)
+	}
 	if bytes.Contains(out, []byte("initdone")) {
 		fmt.Println("sinit generated an init function")
 		os.Exit(1)