libgo: update to Go1.17rc2

Reviewed-on: https://go-review.googlesource.com/c/gofrontend/+/341629

45 files changed, 560 insertions, 138 deletions

diff --git a/libgo/misc/cgo/errors/argposition_test.go b/libgo/misc/cgo/errors/argposition_test.go
new file mode 100644
index 00000000000..331095f7473
--- /dev/null
+++ b/libgo/misc/cgo/errors/argposition_test.go
@@ -0,0 +1,134 @@
+// Copyright 2021 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 42580: cmd/cgo: shifting identifier position in ast
+
+package errorstest
+
+import (
+	"bytes"
+	"fmt"
+	"go/ast"
+	"go/parser"
+	"go/token"
+	"io/ioutil"
+	"os"
+	"os/exec"
+	"path/filepath"
+	"strings"
+	"testing"
+)
+
+type ShortPosition struct {
+	Line    int
+	Column  int
+	Visited bool
+}
+
+type IdentPositionInfo map[string][]ShortPosition
+
+type Visitor struct {
+	identPosInfo IdentPositionInfo
+	fset         *token.FileSet
+	t            *testing.T
+}
+
+func (v *Visitor) Visit(node ast.Node) ast.Visitor {
+	if ident, ok := node.(*ast.Ident); ok {
+		if expectedPositions, ok := v.identPosInfo[ident.Name]; ok {
+			gotMatch := false
+			var errorMessage strings.Builder
+			for caseIndex, expectedPos := range expectedPositions {
+				actualPosition := v.fset.PositionFor(ident.Pos(), true)
+				errorOccured := false
+				if expectedPos.Line != actualPosition.Line {
+					fmt.Fprintf(&errorMessage, "wrong line number for ident %s: expected: %d got: %d\n", ident.Name, expectedPos.Line, actualPosition.Line)
+					errorOccured = true
+				}
+				if expectedPos.Column != actualPosition.Column {
+					fmt.Fprintf(&errorMessage, "wrong column number for ident %s: expected: %d got: %d\n", ident.Name, expectedPos.Column, actualPosition.Column)
+					errorOccured = true
+				}
+				if errorOccured {
+					continue
+				}
+				gotMatch = true
+				expectedPositions[caseIndex].Visited = true
+			}
+
+			if !gotMatch {
+				v.t.Errorf(errorMessage.String())
+			}
+		}
+	}
+	return v
+}
+
+func TestArgumentsPositions(t *testing.T) {
+	testdata, err := filepath.Abs("testdata")
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	tmpPath := t.TempDir()
+
+	dir := filepath.Join(tmpPath, "src", "testpositions")
+	if err := os.MkdirAll(dir, 0755); err != nil {
+		t.Fatal(err)
+	}
+
+	cmd := exec.Command("go", "tool", "cgo",
+		"-srcdir", testdata,
+		"-objdir", dir,
+		"issue42580.go")
+	cmd.Stderr = new(bytes.Buffer)
+
+	err = cmd.Run()
+	if err != nil {
+		t.Fatalf("%s: %v\n%s", cmd, err, cmd.Stderr)
+	}
+	mainProcessed, err := ioutil.ReadFile(filepath.Join(dir, "issue42580.cgo1.go"))
+	if err != nil {
+		t.Fatal(err)
+	}
+	fset := token.NewFileSet()
+	f, err := parser.ParseFile(fset, "", mainProcessed, parser.AllErrors)
+	if err != nil {
+		fmt.Println(err)
+		return
+	}
+
+	expectation := IdentPositionInfo{
+		"checkedPointer": []ShortPosition{
+			ShortPosition{
+				Line:   32,
+				Column: 56,
+			},
+		},
+		"singleInnerPointerChecked": []ShortPosition{
+			ShortPosition{
+				Line:   37,
+				Column: 91,
+			},
+		},
+		"doublePointerChecked": []ShortPosition{
+			ShortPosition{
+				Line:   42,
+				Column: 91,
+			},
+		},
+	}
+	for _, decl := range f.Decls {
+		if fdecl, ok := decl.(*ast.FuncDecl); ok {
+			ast.Walk(&Visitor{expectation, fset, t}, fdecl.Body)
+		}
+	}
+	for ident, positions := range expectation {
+		for _, position := range positions {
+			if !position.Visited {
+				t.Errorf("Position %d:%d missed for %s ident", position.Line, position.Column, ident)
+			}
+		}
+	}
+}
diff --git a/libgo/misc/cgo/errors/badsym_test.go b/libgo/misc/cgo/errors/badsym_test.go
index b2701bf922e..fc687567bf7 100644
--- a/libgo/misc/cgo/errors/badsym_test.go
+++ b/libgo/misc/cgo/errors/badsym_test.go
@@ -6,7 +6,6 @@ package errorstest
 
 import (
 	"bytes"
-	"io/ioutil"
 	"os"
 	"os/exec"
 	"path/filepath"
@@ -55,7 +54,7 @@ func TestBadSymbol(t *testing.T) {
 
 	makeFile := func(mdir, base, source string) string {
 		ret := filepath.Join(mdir, base)
-		if err := ioutil.WriteFile(ret, []byte(source), 0644); err != nil {
+		if err := os.WriteFile(ret, []byte(source), 0644); err != nil {
 			t.Fatal(err)
 		}
 		return ret
@@ -100,7 +99,7 @@ func TestBadSymbol(t *testing.T) {
 	// _cgo_import.go.
 
 	rewrite := func(from, to string) {
-		obj, err := ioutil.ReadFile(from)
+		obj, err := os.ReadFile(from)
 		if err != nil {
 			t.Fatal(err)
 		}
@@ -115,7 +114,7 @@ func TestBadSymbol(t *testing.T) {
 
 		obj = bytes.ReplaceAll(obj, []byte(magicInput), []byte(magicReplace))
 
-		if err := ioutil.WriteFile(to, obj, 0644); err != nil {
+		if err := os.WriteFile(to, obj, 0644); err != nil {
 			t.Fatal(err)
 		}
 	}
diff --git a/libgo/misc/cgo/errors/errors_test.go b/libgo/misc/cgo/errors/errors_test.go
index 1bdf843451d..68a30a44fe4 100644
--- a/libgo/misc/cgo/errors/errors_test.go
+++ b/libgo/misc/cgo/errors/errors_test.go
@@ -7,7 +7,6 @@ package errorstest
 import (
 	"bytes"
 	"fmt"
-	"io/ioutil"
 	"os"
 	"os/exec"
 	"path/filepath"
@@ -25,7 +24,7 @@ func check(t *testing.T, file string) {
 	t.Run(file, func(t *testing.T) {
 		t.Parallel()
 
-		contents, err := ioutil.ReadFile(path(file))
+		contents, err := os.ReadFile(path(file))
 		if err != nil {
 			t.Fatal(err)
 		}
@@ -41,7 +40,8 @@ func check(t *testing.T, file string) {
 			if len(frags) == 1 {
 				continue
 			}
-			re, err := regexp.Compile(string(frags[1]))
+			frag := fmt.Sprintf(":%d:.*%s", i+1, frags[1])
+			re, err := regexp.Compile(frag)
 			if err != nil {
 				t.Errorf("Invalid regexp after `ERROR HERE: `: %#q", frags[1])
 				continue
@@ -56,7 +56,7 @@ func check(t *testing.T, file string) {
 }
 
 func expect(t *testing.T, file string, errors []*regexp.Regexp) {
-	dir, err := ioutil.TempDir("", filepath.Base(t.Name()))
+	dir, err := os.MkdirTemp("", filepath.Base(t.Name()))
 	if err != nil {
 		t.Fatal(err)
 	}
diff --git a/libgo/misc/cgo/errors/ptr_test.go b/libgo/misc/cgo/errors/ptr_test.go
index 4a46b6023bb..0f39dc8e547 100644
--- a/libgo/misc/cgo/errors/ptr_test.go
+++ b/libgo/misc/cgo/errors/ptr_test.go
@@ -10,7 +10,6 @@ import (
 	"bytes"
 	"flag"
 	"fmt"
-	"io/ioutil"
 	"os"
 	"os/exec"
 	"path/filepath"
@@ -463,7 +462,7 @@ func buildPtrTests(t *testing.T) (dir, exe string) {
 		gopath = *tmp
 		dir = ""
 	} else {
-		d, err := ioutil.TempDir("", filepath.Base(t.Name()))
+		d, err := os.MkdirTemp("", filepath.Base(t.Name()))
 		if err != nil {
 			t.Fatal(err)
 		}
@@ -475,7 +474,7 @@ func buildPtrTests(t *testing.T) (dir, exe string) {
 	if err := os.MkdirAll(src, 0777); err != nil {
 		t.Fatal(err)
 	}
-	if err := ioutil.WriteFile(filepath.Join(src, "go.mod"), []byte("module ptrtest"), 0666); err != nil {
+	if err := os.WriteFile(filepath.Join(src, "go.mod"), []byte("module ptrtest"), 0666); err != nil {
 		t.Fatal(err)
 	}
 
@@ -535,10 +534,10 @@ func buildPtrTests(t *testing.T) (dir, exe string) {
 	fmt.Fprintf(&cgo1, "}\n\n")
 	fmt.Fprintf(&cgo1, "%s\n", ptrTestMain)
 
-	if err := ioutil.WriteFile(filepath.Join(src, "cgo1.go"), cgo1.Bytes(), 0666); err != nil {
+	if err := os.WriteFile(filepath.Join(src, "cgo1.go"), cgo1.Bytes(), 0666); err != nil {
 		t.Fatal(err)
 	}
-	if err := ioutil.WriteFile(filepath.Join(src, "cgo2.go"), cgo2.Bytes(), 0666); err != nil {
+	if err := os.WriteFile(filepath.Join(src, "cgo2.go"), cgo2.Bytes(), 0666); err != nil {
 		t.Fatal(err)
 	}
 
diff --git a/libgo/misc/cgo/errors/testdata/err2.go b/libgo/misc/cgo/errors/testdata/err2.go
index 1d22401aee5..a90598fe35b 100644
--- a/libgo/misc/cgo/errors/testdata/err2.go
+++ b/libgo/misc/cgo/errors/testdata/err2.go
@@ -40,15 +40,15 @@ func main() {
 	C.foop = x // ERROR HERE
 
 	// issue 13129: used to output error about C.unsignedshort with CC=clang
-	var x C.ushort
-	x = int(0) // ERROR HERE: C\.ushort
+	var x1 C.ushort
+	x1 = int(0) // ERROR HERE: C\.ushort
 
 	// issue 13423
 	_ = C.fopen() // ERROR HERE
 
 	// issue 13467
-	var x rune = '✈'
-	var _ rune = C.transform(x) // ERROR HERE: C\.int
+	var x2 rune = '✈'
+	var _ rune = C.transform(x2) // ERROR HERE: C\.int
 
 	// issue 13635: used to output error about C.unsignedchar.
 	// This test tests all such types.
@@ -91,10 +91,10 @@ func main() {
 
 	// issue 26745
 	_ = func(i int) int {
-		return C.i + 1 // ERROR HERE: :13
+		return C.i + 1 // ERROR HERE: 14
 	}
 	_ = func(i int) {
-		C.fi(i) // ERROR HERE: :6
+		C.fi(i) // ERROR HERE: 7
 	}
 
 	C.fi = C.fi // ERROR HERE
diff --git a/libgo/misc/cgo/errors/testdata/issue42580.go b/libgo/misc/cgo/errors/testdata/issue42580.go
new file mode 100644
index 00000000000..aba80dfebad
--- /dev/null
+++ b/libgo/misc/cgo/errors/testdata/issue42580.go
@@ -0,0 +1,44 @@
+// Copyright 2021 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 42580: cmd/cgo: shifting identifier position in ast
+
+package cgotest
+
+// typedef int (*intFunc) ();
+//
+// char* strarg = "";
+//
+// int func_with_char(char* arg, void* dummy)
+// {return 5;}
+//
+// int* get_arr(char* arg, void* dummy)
+// {return NULL;}
+import "C"
+import "unsafe"
+
+// Test variables
+var (
+	checkedPointer            = []byte{1}
+	doublePointerChecked      = []byte{1}
+	singleInnerPointerChecked = []byte{1}
+)
+
+// This test checks the positions of variable identifiers.
+// Changing the positions of the test variables idents after this point will break the test.
+
+func TestSingleArgumentCast() C.int {
+	retcode := C.func_with_char((*C.char)(unsafe.Pointer(&checkedPointer[0])), unsafe.Pointer(C.strarg))
+	return retcode
+}
+
+func TestSingleArgumentCastRecFuncAsSimpleArg() C.int {
+	retcode := C.func_with_char((*C.char)(unsafe.Pointer(C.get_arr((*C.char)(unsafe.Pointer(&singleInnerPointerChecked[0])), unsafe.Pointer(C.strarg)))), nil)
+	return retcode
+}
+
+func TestSingleArgumentCastRecFunc() C.int {
+	retcode := C.func_with_char((*C.char)(unsafe.Pointer(C.get_arr((*C.char)(unsafe.Pointer(&doublePointerChecked[0])), unsafe.Pointer(C.strarg)))), unsafe.Pointer(C.strarg))
+	return retcode
+}
diff --git a/libgo/misc/cgo/life/life_test.go b/libgo/misc/cgo/life/life_test.go
index 3c95d87d8ad..0becb262b43 100644
--- a/libgo/misc/cgo/life/life_test.go
+++ b/libgo/misc/cgo/life/life_test.go
@@ -6,7 +6,6 @@ package life_test
 
 import (
 	"bytes"
-	"io/ioutil"
 	"log"
 	"os"
 	"os/exec"
@@ -21,7 +20,7 @@ func TestMain(m *testing.M) {
 }
 
 func testMain(m *testing.M) int {
-	GOPATH, err := ioutil.TempDir("", "cgolife")
+	GOPATH, err := os.MkdirTemp("", "cgolife")
 	if err != nil {
 		log.Panic(err)
 	}
@@ -38,7 +37,7 @@ func testMain(m *testing.M) int {
 		log.Panic(err)
 	}
 	os.Setenv("PWD", modRoot)
-	if err := ioutil.WriteFile("go.mod", []byte("module cgolife\n"), 0666); err != nil {
+	if err := os.WriteFile("go.mod", []byte("module cgolife\n"), 0666); err != nil {
 		log.Panic(err)
 	}
 
diff --git a/libgo/misc/cgo/stdio/stdio_test.go b/libgo/misc/cgo/stdio/stdio_test.go
index ab5d328f676..675418f98d0 100644
--- a/libgo/misc/cgo/stdio/stdio_test.go
+++ b/libgo/misc/cgo/stdio/stdio_test.go
@@ -6,7 +6,6 @@ package stdio_test
 
 import (
 	"bytes"
-	"io/ioutil"
 	"log"
 	"os"
 	"os/exec"
@@ -21,7 +20,7 @@ func TestMain(m *testing.M) {
 }
 
 func testMain(m *testing.M) int {
-	GOPATH, err := ioutil.TempDir("", "cgostdio")
+	GOPATH, err := os.MkdirTemp("", "cgostdio")
 	if err != nil {
 		log.Panic(err)
 	}
@@ -38,7 +37,7 @@ func testMain(m *testing.M) int {
 		log.Panic(err)
 	}
 	os.Setenv("PWD", modRoot)
-	if err := ioutil.WriteFile("go.mod", []byte("module cgostdio\n"), 0666); err != nil {
+	if err := os.WriteFile("go.mod", []byte("module cgostdio\n"), 0666); err != nil {
 		log.Panic(err)
 	}
 
diff --git a/libgo/misc/cgo/test/callback.go b/libgo/misc/cgo/test/callback.go
index 814888e3ac5..08dd9b39d81 100644
--- a/libgo/misc/cgo/test/callback.go
+++ b/libgo/misc/cgo/test/callback.go
@@ -182,7 +182,7 @@ func testCallbackCallers(t *testing.T) {
 		"runtime.cgocallbackg1",
 		"runtime.cgocallbackg",
 		"runtime.cgocallback",
-		"runtime.asmcgocall",
+		"runtime.systemstack_switch",
 		"runtime.cgocall",
 		"test._Cfunc_callback",
 		"test.nestedCall.func1",
diff --git a/libgo/misc/cgo/test/cgo_test.go b/libgo/misc/cgo/test/cgo_test.go
index f7a76d047bd..143f23f0e0c 100644
--- a/libgo/misc/cgo/test/cgo_test.go
+++ b/libgo/misc/cgo/test/cgo_test.go
@@ -59,6 +59,7 @@ func Test28896(t *testing.T)                 { test28896(t) }
 func Test30065(t *testing.T)                 { test30065(t) }
 func Test32579(t *testing.T)                 { test32579(t) }
 func Test31891(t *testing.T)                 { test31891(t) }
+func Test45451(t *testing.T)                 { test45451(t) }
 func TestAlign(t *testing.T)                 { testAlign(t) }
 func TestAtol(t *testing.T)                  { testAtol(t) }
 func TestBlocking(t *testing.T)              { testBlocking(t) }
@@ -80,6 +81,7 @@ func TestNamedEnum(t *testing.T)             { testNamedEnum(t) }
 func TestCastToEnum(t *testing.T)            { testCastToEnum(t) }
 func TestErrno(t *testing.T)                 { testErrno(t) }
 func TestFpVar(t *testing.T)                 { testFpVar(t) }
+func TestHandle(t *testing.T)                { testHandle(t) }
 func TestHelpers(t *testing.T)               { testHelpers(t) }
 func TestLibgcc(t *testing.T)                { testLibgcc(t) }
 func TestMultipleAssign(t *testing.T)        { testMultipleAssign(t) }
diff --git a/libgo/misc/cgo/test/issue1435.go b/libgo/misc/cgo/test/issue1435.go
index a1c7cacde73..91db155c90b 100644
--- a/libgo/misc/cgo/test/issue1435.go
+++ b/libgo/misc/cgo/test/issue1435.go
@@ -2,13 +2,15 @@
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
+//go:build linux && cgo
 // +build linux,cgo
 
 package cgotest
 
 import (
 	"fmt"
-	"io/ioutil"
+	"os"
+	"sort"
 	"strings"
 	"syscall"
 	"testing"
@@ -64,7 +66,7 @@ import "C"
 func compareStatus(filter, expect string) error {
 	expected := filter + expect
 	pid := syscall.Getpid()
-	fs, err := ioutil.ReadDir(fmt.Sprintf("/proc/%d/task", pid))
+	fs, err := os.ReadDir(fmt.Sprintf("/proc/%d/task", pid))
 	if err != nil {
 		return fmt.Errorf("unable to find %d tasks: %v", pid, err)
 	}
@@ -72,7 +74,7 @@ func compareStatus(filter, expect string) error {
 	foundAThread := false
 	for _, f := range fs {
 		tf := fmt.Sprintf("/proc/%s/status", f.Name())
-		d, err := ioutil.ReadFile(tf)
+		d, err := os.ReadFile(tf)
 		if err != nil {
 			// There are a surprising number of ways this
 			// can error out on linux.  We've seen all of
@@ -105,11 +107,23 @@ func compareStatus(filter, expect string) error {
 				// "Pid:\t".
 			}
 			if strings.HasPrefix(line, filter) {
-				if line != expected {
-					return fmt.Errorf("%q got:%q want:%q (bad) [pid=%d file:'%s' %v]\n", tf, line, expected, pid, string(d), expectedProc)
+				if line == expected {
+					foundAThread = true
+					break
+				}
+				if filter == "Groups:" && strings.HasPrefix(line, "Groups:\t") {
+					// https://github.com/golang/go/issues/46145
+					// Containers don't reliably output this line in sorted order so manually sort and compare that.
+					a := strings.Split(line[8:], " ")
+					sort.Strings(a)
+					got := strings.Join(a, " ")
+					if got == expected[8:] {
+						foundAThread = true
+						break
+					}
+
 				}
-				foundAThread = true
-				break
+				return fmt.Errorf("%q got:%q want:%q (bad) [pid=%d file:'%s' %v]\n", tf, line, expected, pid, string(d), expectedProc)
 			}
 		}
 	}
diff --git a/libgo/misc/cgo/test/issue6997_linux.go b/libgo/misc/cgo/test/issue6997_linux.go
index 0c98ea0794e..4acc8c1a070 100644
--- a/libgo/misc/cgo/test/issue6997_linux.go
+++ b/libgo/misc/cgo/test/issue6997_linux.go
@@ -2,10 +2,11 @@
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
+//go:build !android
 // +build !android
 
 // Test that pthread_cancel works as expected
-// (NPTL uses SIGRTMIN to implement thread cancelation)
+// (NPTL uses SIGRTMIN to implement thread cancellation)
 // See https://golang.org/issue/6997
 package cgotest
 
@@ -17,8 +18,10 @@ extern int CancelThread();
 */
 import "C"
 
-import "testing"
-import "time"
+import (
+	"testing"
+	"time"
+)
 
 func test6997(t *testing.T) {
 	r := C.StartThread()
diff --git a/libgo/misc/cgo/test/issue8148.c b/libgo/misc/cgo/test/issue8148.c
new file mode 100644
index 00000000000..927b4346cbe
--- /dev/null
+++ b/libgo/misc/cgo/test/issue8148.c
@@ -0,0 +1,11 @@
+// Copyright 2014 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.
+
+#include "_cgo_export.h"
+
+int get8148(void) {
+	T t;
+	t.i = 42;
+	return issue8148Callback(&t);
+}
diff --git a/libgo/misc/cgo/test/issue8148.go b/libgo/misc/cgo/test/issue8148.go
index f704788aef8..aee9003d507 100644
--- a/libgo/misc/cgo/test/issue8148.go
+++ b/libgo/misc/cgo/test/issue8148.go
@@ -10,14 +10,7 @@ package cgotest
 
 /*
 typedef struct { int i; } T;
-
-int issue8148Callback(T*);
-
-static int get() {
-	T t;
-	t.i = 42;
-	return issue8148Callback(&t);
-}
+int get8148(void);
 */
 import "C"
 
@@ -27,5 +20,5 @@ func issue8148Callback(t *C.T) C.int {
 }
 
 func Issue8148() int {
-	return int(C.get())
+	return int(C.get8148())
 }
diff --git a/libgo/misc/cgo/test/pkg_test.go b/libgo/misc/cgo/test/pkg_test.go
index 94abaa03e8d..14013a4cd96 100644
--- a/libgo/misc/cgo/test/pkg_test.go
+++ b/libgo/misc/cgo/test/pkg_test.go
@@ -5,7 +5,6 @@
 package cgotest
 
 import (
-	"io/ioutil"
 	"os"
 	"os/exec"
 	"path/filepath"
@@ -37,7 +36,7 @@ func TestCrossPackageTests(t *testing.T) {
 		}
 	}
 
-	GOPATH, err := ioutil.TempDir("", "cgotest")
+	GOPATH, err := os.MkdirTemp("", "cgotest")
 	if err != nil {
 		t.Fatal(err)
 	}
@@ -47,7 +46,7 @@ func TestCrossPackageTests(t *testing.T) {
 	if err := overlayDir(modRoot, "testdata"); err != nil {
 		t.Fatal(err)
 	}
-	if err := ioutil.WriteFile(filepath.Join(modRoot, "go.mod"), []byte("module cgotest\n"), 0666); err != nil {
+	if err := os.WriteFile(filepath.Join(modRoot, "go.mod"), []byte("module cgotest\n"), 0666); err != nil {
 		t.Fatal(err)
 	}
 
diff --git a/libgo/misc/cgo/test/setgid_linux.go b/libgo/misc/cgo/test/setgid_linux.go
index 6773f94d3d6..7c64946cb34 100644
--- a/libgo/misc/cgo/test/setgid_linux.go
+++ b/libgo/misc/cgo/test/setgid_linux.go
@@ -2,7 +2,7 @@
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
-// Test that setgid does not hang on GNU/Linux.
+// Test that setgid does not hang on Linux.
 // See https://golang.org/issue/3871 for details.
 
 package cgotest
diff --git a/libgo/misc/cgo/test/test.go b/libgo/misc/cgo/test/test.go
index 65823b1ca0e..3b8f548b13d 100644
--- a/libgo/misc/cgo/test/test.go
+++ b/libgo/misc/cgo/test/test.go
@@ -899,6 +899,10 @@ static uint16_t issue31093F(uint16_t v) { return v; }
 // issue 32579
 typedef struct S32579 { unsigned char data[1]; } S32579;
 
+// issue 37033, cgo.Handle
+extern void GoFunc37033(uintptr_t handle);
+void cFunc37033(uintptr_t handle) { GoFunc37033(handle); }
+
 // issue 38649
 // Test that #define'd type aliases work.
 #define netbsd_gid unsigned int
@@ -908,6 +912,9 @@ typedef struct S32579 { unsigned char data[1]; } S32579;
 enum Enum40494 { X_40494 };
 union Union40494 { int x; };
 void issue40494(enum Enum40494 e, union Union40494* up) {}
+
+// Issue 45451, bad handling of go:notinheap types.
+typedef struct issue45451Undefined issue45451;
 */
 import "C"
 
@@ -920,6 +927,7 @@ import (
 	"os/signal"
 	"reflect"
 	"runtime"
+	"runtime/cgo"
 	"sync"
 	"syscall"
 	"testing"
@@ -2230,6 +2238,23 @@ func test32579(t *testing.T) {
 	}
 }
 
+// issue 37033, check if cgo.Handle works properly
+
+func testHandle(t *testing.T) {
+	ch := make(chan int)
+
+	for i := 0; i < 42; i++ {
+		h := cgo.NewHandle(ch)
+		go func() {
+			C.cFunc37033(C.uintptr_t(h))
+		}()
+		if v := <-ch; issue37033 != v {
+			t.Fatalf("unexpected receiving value: got %d, want %d", v, issue37033)
+		}
+		h.Delete()
+	}
+}
+
 // issue 38649
 
 var issue38649 C.netbsd_gid = 42
@@ -2244,3 +2269,19 @@ var issue39877 *C.void = nil
 func Issue40494() {
 	C.issue40494(C.enum_Enum40494(C.X_40494), (*C.union_Union40494)(nil))
 }
+
+// Issue 45451.
+func test45451(t *testing.T) {
+	var u *C.issue45451
+	typ := reflect.ValueOf(u).Type().Elem()
+
+	// The type is undefined in C so allocating it should panic.
+	defer func() {
+		if r := recover(); r == nil {
+			t.Error("expected panic")
+		}
+	}()
+
+	_ = reflect.New(typ)
+	t.Errorf("reflect.New(%v) should have panicked", typ)
+}
diff --git a/libgo/misc/cgo/test/testdata/issue9400/asm_386.s b/libgo/misc/cgo/test/testdata/issue9400/asm_386.s
index 7f158b5c39d..96b8b60c10f 100644
--- a/libgo/misc/cgo/test/testdata/issue9400/asm_386.s
+++ b/libgo/misc/cgo/test/testdata/issue9400/asm_386.s
@@ -2,7 +2,7 @@
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
-// +build !gccgo
+// +build gc
 
 #include "textflag.h"
 
diff --git a/libgo/misc/cgo/test/testdata/issue9400/asm_amd64x.s b/libgo/misc/cgo/test/testdata/issue9400/asm_amd64x.s
index 48b86190a59..99509bce5e1 100644
--- a/libgo/misc/cgo/test/testdata/issue9400/asm_amd64x.s
+++ b/libgo/misc/cgo/test/testdata/issue9400/asm_amd64x.s
@@ -3,7 +3,7 @@
 // license that can be found in the LICENSE file.
 
 // +build amd64 amd64p32
-// +build !gccgo
+// +build gc
 
 #include "textflag.h"
 
diff --git a/libgo/misc/cgo/test/testdata/issue9400/asm_arm.s b/libgo/misc/cgo/test/testdata/issue9400/asm_arm.s
index 96c278520f3..cc92856c2ff 100644
--- a/libgo/misc/cgo/test/testdata/issue9400/asm_arm.s
+++ b/libgo/misc/cgo/test/testdata/issue9400/asm_arm.s
@@ -2,7 +2,7 @@
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
-// +build !gccgo
+// +build gc
 
 #include "textflag.h"
 
diff --git a/libgo/misc/cgo/test/testdata/issue9400/asm_arm64.s b/libgo/misc/cgo/test/testdata/issue9400/asm_arm64.s
index 2ebbfcca3b6..2565793f9ab 100644
--- a/libgo/misc/cgo/test/testdata/issue9400/asm_arm64.s
+++ b/libgo/misc/cgo/test/testdata/issue9400/asm_arm64.s
@@ -2,7 +2,7 @@
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
-// +build !gccgo
+// +build gc
 
 #include "textflag.h"
 
diff --git a/libgo/misc/cgo/test/testdata/issue9400/asm_mips64x.s b/libgo/misc/cgo/test/testdata/issue9400/asm_mips64x.s
index 63dc90605e6..693231ddfe1 100644
--- a/libgo/misc/cgo/test/testdata/issue9400/asm_mips64x.s
+++ b/libgo/misc/cgo/test/testdata/issue9400/asm_mips64x.s
@@ -3,7 +3,7 @@
 // license that can be found in the LICENSE file.
 
 // +build mips64 mips64le
-// +build !gccgo
+// +build gc
 
 #include "textflag.h"
 
diff --git a/libgo/misc/cgo/test/testdata/issue9400/asm_mipsx.s b/libgo/misc/cgo/test/testdata/issue9400/asm_mipsx.s
index 7a927351942..63261bbf9d0 100644
--- a/libgo/misc/cgo/test/testdata/issue9400/asm_mipsx.s
+++ b/libgo/misc/cgo/test/testdata/issue9400/asm_mipsx.s
@@ -3,7 +3,7 @@
 // license that can be found in the LICENSE file.
 
 // +build mips mipsle
-// +build !gccgo
+// +build gc
 
 #include "textflag.h"
 
diff --git a/libgo/misc/cgo/test/testdata/issue9400/asm_ppc64x.s b/libgo/misc/cgo/test/testdata/issue9400/asm_ppc64x.s
index c88ec3b21e7..b5613fb6ec7 100644
--- a/libgo/misc/cgo/test/testdata/issue9400/asm_ppc64x.s
+++ b/libgo/misc/cgo/test/testdata/issue9400/asm_ppc64x.s
@@ -3,7 +3,7 @@
 // license that can be found in the LICENSE file.
 
 // +build ppc64 ppc64le
-// +build !gccgo
+// +build gc
 
 #include "textflag.h"
 
diff --git a/libgo/misc/cgo/test/testdata/issue9400/asm_riscv64.s b/libgo/misc/cgo/test/testdata/issue9400/asm_riscv64.s
index 20fcc0066d6..244dadac350 100644
--- a/libgo/misc/cgo/test/testdata/issue9400/asm_riscv64.s
+++ b/libgo/misc/cgo/test/testdata/issue9400/asm_riscv64.s
@@ -3,7 +3,7 @@
 // license that can be found in the LICENSE file.
 
 // +build riscv64
-// +build !gccgo
+// +build gc
 
 #include "textflag.h"
 
diff --git a/libgo/misc/cgo/test/testdata/issue9400/asm_s390x.s b/libgo/misc/cgo/test/testdata/issue9400/asm_s390x.s
index fc9ad724c15..4856492958b 100644
--- a/libgo/misc/cgo/test/testdata/issue9400/asm_s390x.s
+++ b/libgo/misc/cgo/test/testdata/issue9400/asm_s390x.s
@@ -2,7 +2,7 @@
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
-// +build !gccgo
+// +build gc
 
 #include "textflag.h"
 
diff --git a/libgo/misc/cgo/test/testx.c b/libgo/misc/cgo/test/testx.c
new file mode 100644
index 00000000000..1258e326a41
--- /dev/null
+++ b/libgo/misc/cgo/test/testx.c
@@ -0,0 +1,24 @@
+// Copyright 2021 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.
+
+#include "_cgo_export.h"
+
+void lockOSThreadC(void) {
+	lockOSThreadCallback();
+}
+
+void issue7978c(uint32_t *sync) {
+	while(__atomic_load_n(sync, __ATOMIC_SEQ_CST) != 0)
+		;
+	__atomic_add_fetch(sync, 1, __ATOMIC_SEQ_CST);
+	while(__atomic_load_n(sync, __ATOMIC_SEQ_CST) != 2)
+		;
+	issue7978cb();
+	__atomic_add_fetch(sync, 1, __ATOMIC_SEQ_CST);
+	while(__atomic_load_n(sync, __ATOMIC_SEQ_CST) != 6)
+		;
+}
+
+void f7665(void) {
+}
diff --git a/libgo/misc/cgo/test/testx.go b/libgo/misc/cgo/test/testx.go
index 2b2e69ec00f..823c3e13d29 100644
--- a/libgo/misc/cgo/test/testx.go
+++ b/libgo/misc/cgo/test/testx.go
@@ -12,6 +12,7 @@ package cgotest
 
 import (
 	"runtime"
+	"runtime/cgo"
 	"runtime/debug"
 	"strings"
 	"sync"
@@ -26,7 +27,6 @@ import (
 extern void doAdd(int, int);
 
 // issue 1328
-extern void BackIntoGo(void);
 void IntoC(void);
 
 // issue 1560
@@ -38,11 +38,7 @@ long long mysleep(int seconds);
 long long twoSleep(int);
 
 // issue 3775
-void lockOSThreadCallback(void);
-inline static void lockOSThreadC(void)
-{
-        lockOSThreadCallback();
-}
+void lockOSThreadC(void);
 int usleep(unsigned usec);
 
 // issue 4054 part 2 - part 1 in test.go
@@ -81,21 +77,9 @@ extern void f7665(void);
 
 #include <stdint.h>
 
-void issue7978cb(void);
-
 // use ugly atomic variable sync since that doesn't require calling back into
 // Go code or OS dependencies
-static void issue7978c(uint32_t *sync) {
-	while(__atomic_load_n(sync, __ATOMIC_SEQ_CST) != 0)
-		;
-	__atomic_add_fetch(sync, 1, __ATOMIC_SEQ_CST);
-	while(__atomic_load_n(sync, __ATOMIC_SEQ_CST) != 2)
-		;
-	issue7978cb();
-	__atomic_add_fetch(sync, 1, __ATOMIC_SEQ_CST);
-	while(__atomic_load_n(sync, __ATOMIC_SEQ_CST) != 6)
-		;
-}
+void issue7978c(uint32_t *sync);
 
 // issue 8331 part 2 - part 1 in test.go
 // A typedef of an unnamed struct is the same struct when
@@ -428,9 +412,6 @@ func test6907Go(t *testing.T) {
 
 // issue 7665
 
-//export f7665
-func f7665() {}
-
 var bad7665 unsafe.Pointer = C.f7665
 var good7665 uintptr = uintptr(C.f7665)
 
@@ -558,6 +539,17 @@ func test31891(t *testing.T) {
 	C.callIssue31891()
 }
 
+// issue 37033, check if cgo.Handle works properly
+
+var issue37033 = 42
+
+//export GoFunc37033
+func GoFunc37033(handle C.uintptr_t) {
+	h := cgo.Handle(handle)
+	ch := h.Value().(chan int)
+	ch <- issue37033
+}
+
 // issue 38408
 // A typedef pointer can be used as the element type.
 // No runtime test; just make sure it compiles.
diff --git a/libgo/misc/cgo/testcarchive/carchive_test.go b/libgo/misc/cgo/testcarchive/carchive_test.go
index b67cb2e0cd0..e5db0d628a4 100644
--- a/libgo/misc/cgo/testcarchive/carchive_test.go
+++ b/libgo/misc/cgo/testcarchive/carchive_test.go
@@ -10,7 +10,6 @@ import (
 	"debug/elf"
 	"flag"
 	"fmt"
-	"io/ioutil"
 	"log"
 	"os"
 	"os/exec"
@@ -53,7 +52,7 @@ func testMain(m *testing.M) int {
 	// We need a writable GOPATH in which to run the tests.
 	// Construct one in a temporary directory.
 	var err error
-	GOPATH, err = ioutil.TempDir("", "carchive_test")
+	GOPATH, err = os.MkdirTemp("", "carchive_test")
 	if err != nil {
 		log.Panic(err)
 	}
@@ -74,7 +73,7 @@ func testMain(m *testing.M) int {
 		log.Panic(err)
 	}
 	os.Setenv("PWD", modRoot)
-	if err := ioutil.WriteFile("go.mod", []byte("module testcarchive\n"), 0666); err != nil {
+	if err := os.WriteFile("go.mod", []byte("module testcarchive\n"), 0666); err != nil {
 		log.Panic(err)
 	}
 
@@ -176,7 +175,7 @@ func genHeader(t *testing.T, header, dir string) {
 	// The 'cgo' command generates a number of additional artifacts,
 	// but we're only interested in the header.
 	// Shunt the rest of the outputs to a temporary directory.
-	objDir, err := ioutil.TempDir(GOPATH, "_obj")
+	objDir, err := os.MkdirTemp(GOPATH, "_obj")
 	if err != nil {
 		t.Fatal(err)
 	}
@@ -252,7 +251,7 @@ var badLineRegexp = regexp.MustCompile(`(?m)^#line [0-9]+ "/.*$`)
 // the user and make the files change based on details of the location
 // of GOPATH.
 func checkLineComments(t *testing.T, hdrname string) {
-	hdr, err := ioutil.ReadFile(hdrname)
+	hdr, err := os.ReadFile(hdrname)
 	if err != nil {
 		if !os.IsNotExist(err) {
 			t.Error(err)
@@ -618,7 +617,7 @@ func TestExtar(t *testing.T) {
 		t.Fatal(err)
 	}
 	s := strings.Replace(testar, "PWD", dir, 1)
-	if err := ioutil.WriteFile("testar", []byte(s), 0777); err != nil {
+	if err := os.WriteFile("testar", []byte(s), 0777); err != nil {
 		t.Fatal(err)
 	}
 
@@ -776,7 +775,7 @@ func TestSIGPROF(t *testing.T) {
 // tool with -buildmode=c-archive, it passes -shared to the compiler,
 // so we override that. The go tool doesn't work this way, but Bazel
 // will likely do it in the future. And it ought to work. This test
-// was added because at one time it did not work on PPC GNU/Linux.
+// was added because at one time it did not work on PPC Linux.
 func TestCompileWithoutShared(t *testing.T) {
 	// For simplicity, reuse the signal forwarding test.
 	checkSignalForwardingTest(t)
diff --git a/libgo/misc/cgo/testcarchive/testdata/libgo6/sigprof.go b/libgo/misc/cgo/testcarchive/testdata/libgo6/sigprof.go
index 4cb05dc6178..31527c59af1 100644
--- a/libgo/misc/cgo/testcarchive/testdata/libgo6/sigprof.go
+++ b/libgo/misc/cgo/testcarchive/testdata/libgo6/sigprof.go
@@ -5,7 +5,7 @@
 package main
 
 import (
-	"io/ioutil"
+	"io"
 	"runtime/pprof"
 )
 
@@ -13,7 +13,7 @@ import "C"
 
 //export go_start_profile
 func go_start_profile() {
-	pprof.StartCPUProfile(ioutil.Discard)
+	pprof.StartCPUProfile(io.Discard)
 }
 
 //export go_stop_profile
diff --git a/libgo/misc/cgo/testcshared/cshared_test.go b/libgo/misc/cgo/testcshared/cshared_test.go
index 3a4886cf30a..19ad8c76a83 100644
--- a/libgo/misc/cgo/testcshared/cshared_test.go
+++ b/libgo/misc/cgo/testcshared/cshared_test.go
@@ -11,7 +11,6 @@ import (
 	"encoding/binary"
 	"flag"
 	"fmt"
-	"io/ioutil"
 	"log"
 	"os"
 	"os/exec"
@@ -125,7 +124,7 @@ func testMain(m *testing.M) int {
 	// Copy testdata into GOPATH/src/testcshared, along with a go.mod file
 	// declaring the same path.
 
-	GOPATH, err := ioutil.TempDir("", "cshared_test")
+	GOPATH, err := os.MkdirTemp("", "cshared_test")
 	if err != nil {
 		log.Panic(err)
 	}
@@ -140,7 +139,7 @@ func testMain(m *testing.M) int {
 		log.Panic(err)
 	}
 	os.Setenv("PWD", modRoot)
-	if err := ioutil.WriteFile("go.mod", []byte("module testcshared\n"), 0666); err != nil {
+	if err := os.WriteFile("go.mod", []byte("module testcshared\n"), 0666); err != nil {
 		log.Panic(err)
 	}
 
@@ -260,7 +259,7 @@ func createHeaders() error {
 	// The 'cgo' command generates a number of additional artifacts,
 	// but we're only interested in the header.
 	// Shunt the rest of the outputs to a temporary directory.
-	objDir, err := ioutil.TempDir("", "testcshared_obj")
+	objDir, err := os.MkdirTemp("", "testcshared_obj")
 	if err != nil {
 		return err
 	}
@@ -293,11 +292,60 @@ func createHeaders() error {
 		"-installsuffix", "testcshared",
 		"-o", libgoname,
 		filepath.Join(".", "libgo", "libgo.go")}
+	if GOOS == "windows" && strings.HasSuffix(args[6], ".a") {
+		args[6] = strings.TrimSuffix(args[6], ".a") + ".dll"
+	}
 	cmd = exec.Command(args[0], args[1:]...)
 	out, err = cmd.CombinedOutput()
 	if err != nil {
 		return fmt.Errorf("command failed: %v\n%v\n%s\n", args, err, out)
 	}
+	if GOOS == "windows" {
+		// We can't simply pass -Wl,--out-implib, because this relies on having imports from multiple packages,
+		// which results in the linkers output implib getting overwritten at each step. So instead build the
+		// import library the traditional way, using a def file.
+		err = os.WriteFile("libgo.def",
+			[]byte("LIBRARY libgo.dll\nEXPORTS\n\tDidInitRun\n\tDidMainRun\n\tDivu\n\tFromPkg\n\t_cgo_dummy_export\n"),
+			0644)
+		if err != nil {
+			return fmt.Errorf("unable to write def file: %v", err)
+		}
+		out, err = exec.Command(cc[0], append(cc[1:], "-print-prog-name=dlltool")...).CombinedOutput()
+		if err != nil {
+			return fmt.Errorf("unable to find dlltool path: %v\n%s\n", err, out)
+		}
+		args := []string{strings.TrimSpace(string(out)), "-D", args[6], "-l", libgoname, "-d", "libgo.def"}
+
+		// This is an unfortunate workaround for https://github.com/mstorsjo/llvm-mingw/issues/205 in which
+		// we basically reimplement the contents of the dlltool.sh wrapper: https://git.io/JZFlU
+		dlltoolContents, err := os.ReadFile(args[0])
+		if err != nil {
+			return fmt.Errorf("unable to read dlltool: %v\n", err)
+		}
+		if bytes.HasPrefix(dlltoolContents, []byte("#!/bin/sh")) && bytes.Contains(dlltoolContents, []byte("llvm-dlltool")) {
+			base, name := filepath.Split(args[0])
+			args[0] = filepath.Join(base, "llvm-dlltool")
+			var machine string
+			switch strings.SplitN(name, "-", 2)[0] {
+			case "i686":
+				machine = "i386"
+			case "x86_64":
+				machine = "i386:x86-64"
+			case "armv7":
+				machine = "arm"
+			case "aarch64":
+				machine = "arm64"
+			}
+			if len(machine) > 0 {
+				args = append(args, "-m", machine)
+			}
+		}
+
+		out, err = exec.Command(args[0], args[1:]...).CombinedOutput()
+		if err != nil {
+			return fmt.Errorf("unable to run dlltool to create import library: %v\n%s\n", err, out)
+		}
+	}
 
 	if runtime.GOOS != GOOS && GOOS == "android" {
 		args = append(adbCmd(), "push", libgoname, fmt.Sprintf("%s/%s", androiddir, libgoname))
@@ -381,7 +429,7 @@ func main() {
 
 	srcfile := filepath.Join(tmpdir, "test.go")
 	objfile := filepath.Join(tmpdir, "test.dll")
-	if err := ioutil.WriteFile(srcfile, []byte(prog), 0666); err != nil {
+	if err := os.WriteFile(srcfile, []byte(prog), 0666); err != nil {
 		t.Fatal(err)
 	}
 	argv := []string{"build", "-buildmode=c-shared"}
@@ -401,7 +449,7 @@ func main() {
 	defer f.Close()
 	section := f.Section(".edata")
 	if section == nil {
-		t.Fatalf(".edata section is not present")
+		t.Skip(".edata section is not present")
 	}
 
 	// TODO: deduplicate this struct from cmd/link/internal/ld/pe.go
@@ -643,7 +691,7 @@ func TestPIE(t *testing.T) {
 
 // Test that installing a second time recreates the header file.
 func TestCachedInstall(t *testing.T) {
-	tmpdir, err := ioutil.TempDir("", "cshared")
+	tmpdir, err := os.MkdirTemp("", "cshared")
 	if err != nil {
 		t.Fatal(err)
 	}
@@ -719,14 +767,14 @@ func TestCachedInstall(t *testing.T) {
 // copyFile copies src to dst.
 func copyFile(t *testing.T, dst, src string) {
 	t.Helper()
-	data, err := ioutil.ReadFile(src)
+	data, err := os.ReadFile(src)
 	if err != nil {
 		t.Fatal(err)
 	}
 	if err := os.MkdirAll(filepath.Dir(dst), 0777); err != nil {
 		t.Fatal(err)
 	}
-	if err := ioutil.WriteFile(dst, data, 0666); err != nil {
+	if err := os.WriteFile(dst, data, 0666); err != nil {
 		t.Fatal(err)
 	}
 }
@@ -743,14 +791,19 @@ func TestGo2C2Go(t *testing.T) {
 
 	t.Parallel()
 
-	tmpdir, err := ioutil.TempDir("", "cshared-TestGo2C2Go")
+	tmpdir, err := os.MkdirTemp("", "cshared-TestGo2C2Go")
 	if err != nil {
 		t.Fatal(err)
 	}
 	defer os.RemoveAll(tmpdir)
 
 	lib := filepath.Join(tmpdir, "libtestgo2c2go."+libSuffix)
-	run(t, nil, "go", "build", "-buildmode=c-shared", "-o", lib, "./go2c2go/go")
+	var env []string
+	if GOOS == "windows" && strings.HasSuffix(lib, ".a") {
+		env = append(env, "CGO_LDFLAGS=-Wl,--out-implib,"+lib, "CGO_LDFLAGS_ALLOW=.*")
+		lib = strings.TrimSuffix(lib, ".a") + ".dll"
+	}
+	run(t, env, "go", "build", "-buildmode=c-shared", "-o", lib, "./go2c2go/go")
 
 	cgoCflags := os.Getenv("CGO_CFLAGS")
 	if cgoCflags != "" {
diff --git a/libgo/misc/cgo/testgodefs/testgodefs_test.go b/libgo/misc/cgo/testgodefs/testgodefs_test.go
index 4c2312c1c89..aae34043605 100644
--- a/libgo/misc/cgo/testgodefs/testgodefs_test.go
+++ b/libgo/misc/cgo/testgodefs/testgodefs_test.go
@@ -6,7 +6,6 @@ package testgodefs
 
 import (
 	"bytes"
-	"io/ioutil"
 	"os"
 	"os/exec"
 	"path/filepath"
@@ -34,7 +33,7 @@ func TestGoDefs(t *testing.T) {
 		t.Fatal(err)
 	}
 
-	gopath, err := ioutil.TempDir("", "testgodefs-gopath")
+	gopath, err := os.MkdirTemp("", "testgodefs-gopath")
 	if err != nil {
 		t.Fatal(err)
 	}
@@ -58,20 +57,20 @@ func TestGoDefs(t *testing.T) {
 			t.Fatalf("%s: %v\n%s", strings.Join(cmd.Args, " "), err, cmd.Stderr)
 		}
 
-		if err := ioutil.WriteFile(filepath.Join(dir, fp+"_defs.go"), out, 0644); err != nil {
+		if err := os.WriteFile(filepath.Join(dir, fp+"_defs.go"), out, 0644); err != nil {
 			t.Fatal(err)
 		}
 	}
 
-	main, err := ioutil.ReadFile(filepath.Join("testdata", "main.go"))
+	main, err := os.ReadFile(filepath.Join("testdata", "main.go"))
 	if err != nil {
 		t.Fatal(err)
 	}
-	if err := ioutil.WriteFile(filepath.Join(dir, "main.go"), main, 0644); err != nil {
+	if err := os.WriteFile(filepath.Join(dir, "main.go"), main, 0644); err != nil {
 		t.Fatal(err)
 	}
 
-	if err := ioutil.WriteFile(filepath.Join(dir, "go.mod"), []byte("module testgodefs\ngo 1.14\n"), 0644); err != nil {
+	if err := os.WriteFile(filepath.Join(dir, "go.mod"), []byte("module testgodefs\ngo 1.14\n"), 0644); err != nil {
 		t.Fatal(err)
 	}
 
diff --git a/libgo/misc/cgo/testplugin/plugin_test.go b/libgo/misc/cgo/testplugin/plugin_test.go
index 8869528015d..9697dbf7a78 100644
--- a/libgo/misc/cgo/testplugin/plugin_test.go
+++ b/libgo/misc/cgo/testplugin/plugin_test.go
@@ -9,7 +9,6 @@ import (
 	"context"
 	"flag"
 	"fmt"
-	"io/ioutil"
 	"log"
 	"os"
 	"os/exec"
@@ -31,15 +30,28 @@ func TestMain(m *testing.M) {
 	os.Exit(testMain(m))
 }
 
+// tmpDir is used to cleanup logged commands -- s/tmpDir/$TMPDIR/
+var tmpDir string
+
+// prettyPrintf prints lines with tmpDir sanitized.
+func prettyPrintf(format string, args ...interface{}) {
+	s := fmt.Sprintf(format, args...)
+	if tmpDir != "" {
+		s = strings.ReplaceAll(s, tmpDir, "$TMPDIR")
+	}
+	fmt.Print(s)
+}
+
 func testMain(m *testing.M) int {
 	// Copy testdata into GOPATH/src/testplugin, along with a go.mod file
 	// declaring the same path.
 
-	GOPATH, err := ioutil.TempDir("", "plugin_test")
+	GOPATH, err := os.MkdirTemp("", "plugin_test")
 	if err != nil {
 		log.Panic(err)
 	}
 	defer os.RemoveAll(GOPATH)
+	tmpDir = GOPATH
 
 	modRoot := filepath.Join(GOPATH, "src", "testplugin")
 	altRoot := filepath.Join(GOPATH, "alt", "src", "testplugin")
@@ -50,14 +62,20 @@ func testMain(m *testing.M) int {
 		if err := overlayDir(dstRoot, srcRoot); err != nil {
 			log.Panic(err)
 		}
-		if err := ioutil.WriteFile(filepath.Join(dstRoot, "go.mod"), []byte("module testplugin\n"), 0666); err != nil {
+		prettyPrintf("mkdir -p %s\n", dstRoot)
+		prettyPrintf("rsync -a %s/ %s\n", srcRoot, dstRoot)
+
+		if err := os.WriteFile(filepath.Join(dstRoot, "go.mod"), []byte("module testplugin\n"), 0666); err != nil {
 			log.Panic(err)
 		}
+		prettyPrintf("echo 'module testplugin' > %s/go.mod\n", dstRoot)
 	}
 
 	os.Setenv("GOPATH", filepath.Join(GOPATH, "alt"))
 	if err := os.Chdir(altRoot); err != nil {
 		log.Panic(err)
+	} else {
+		prettyPrintf("cd %s\n", altRoot)
 	}
 	os.Setenv("PWD", altRoot)
 	goCmd(nil, "build", "-buildmode=plugin", "-o", filepath.Join(modRoot, "plugin-mismatch.so"), "./plugin-mismatch")
@@ -65,6 +83,8 @@ func testMain(m *testing.M) int {
 	os.Setenv("GOPATH", GOPATH)
 	if err := os.Chdir(modRoot); err != nil {
 		log.Panic(err)
+	} else {
+		prettyPrintf("cd %s\n", modRoot)
 	}
 	os.Setenv("PWD", modRoot)
 
@@ -72,13 +92,14 @@ func testMain(m *testing.M) int {
 
 	goCmd(nil, "build", "-buildmode=plugin", "./plugin1")
 	goCmd(nil, "build", "-buildmode=plugin", "./plugin2")
-	so, err := ioutil.ReadFile("plugin2.so")
+	so, err := os.ReadFile("plugin2.so")
 	if err != nil {
 		log.Panic(err)
 	}
-	if err := ioutil.WriteFile("plugin2-dup.so", so, 0444); err != nil {
+	if err := os.WriteFile("plugin2-dup.so", so, 0444); err != nil {
 		log.Panic(err)
 	}
+	prettyPrintf("cp plugin2.so plugin2-dup.so\n")
 
 	goCmd(nil, "build", "-buildmode=plugin", "-o=sub/plugin1.so", "./sub/plugin1")
 	goCmd(nil, "build", "-buildmode=plugin", "-o=unnamed1.so", "./unnamed1/main.go")
@@ -95,8 +116,53 @@ func goCmd(t *testing.T, op string, args ...string) {
 	run(t, "go", append([]string{op, "-gcflags", gcflags}, args...)...)
 }
 
+// escape converts a string to something suitable for a shell command line.
+func escape(s string) string {
+	s = strings.Replace(s, "\\", "\\\\", -1)
+	s = strings.Replace(s, "'", "\\'", -1)
+	// Conservative guess at characters that will force quoting
+	if s == "" || strings.ContainsAny(s, "\\ ;#*&$~?!|[]()<>{}`") {
+		s = "'" + s + "'"
+	}
+	return s
+}
+
+// asCommandLine renders cmd as something that could be copy-and-pasted into a command line
+func asCommandLine(cwd string, cmd *exec.Cmd) string {
+	s := "("
+	if cmd.Dir != "" && cmd.Dir != cwd {
+		s += "cd" + escape(cmd.Dir) + ";"
+	}
+	for _, e := range cmd.Env {
+		if !strings.HasPrefix(e, "PATH=") &&
+			!strings.HasPrefix(e, "HOME=") &&
+			!strings.HasPrefix(e, "USER=") &&
+			!strings.HasPrefix(e, "SHELL=") {
+			s += " "
+			s += escape(e)
+		}
+	}
+	// These EVs are relevant to this test.
+	for _, e := range os.Environ() {
+		if strings.HasPrefix(e, "PWD=") ||
+			strings.HasPrefix(e, "GOPATH=") ||
+			strings.HasPrefix(e, "LD_LIBRARY_PATH=") {
+			s += " "
+			s += escape(e)
+		}
+	}
+	for _, a := range cmd.Args {
+		s += " "
+		s += escape(a)
+	}
+	s += " )"
+	return s
+}
+
 func run(t *testing.T, bin string, args ...string) string {
 	cmd := exec.Command(bin, args...)
+	cmdLine := asCommandLine(".", cmd)
+	prettyPrintf("%s\n", cmdLine)
 	cmd.Stderr = new(strings.Builder)
 	out, err := cmd.Output()
 	if err != nil {
@@ -197,6 +263,17 @@ func TestIssue25756(t *testing.T) {
 	}
 }
 
+// Test with main using -buildmode=pie with plugin for issue #43228
+func TestIssue25756pie(t *testing.T) {
+	if os.Getenv("GO_BUILDER_NAME") == "darwin-arm64-11_0-toothrot" {
+		t.Skip("broken on darwin/arm64 builder in sharded mode; see issue 46239")
+	}
+
+	goCmd(t, "build", "-buildmode=plugin", "-o", "life.so", "./issue25756/plugin")
+	goCmd(t, "build", "-buildmode=pie", "-o", "issue25756pie.exe", "./issue25756/main.go")
+	run(t, "./issue25756pie.exe")
+}
+
 func TestMethod(t *testing.T) {
 	// Exported symbol's method must be live.
 	goCmd(t, "build", "-buildmode=plugin", "-o", "plugin.so", "./method/plugin.go")
diff --git a/libgo/misc/cgo/testplugin/testdata/method2/main.go b/libgo/misc/cgo/testplugin/testdata/method2/main.go
index 6a87e7b6a0f..89afbda3d47 100644
--- a/libgo/misc/cgo/testplugin/testdata/method2/main.go
+++ b/libgo/misc/cgo/testplugin/testdata/method2/main.go
@@ -15,7 +15,7 @@ import (
 
 var t p.T
 
-type I interface { M() }
+type I interface{ M() }
 
 func main() {
 	pl, err := plugin.Open("method2.so")
diff --git a/libgo/misc/cgo/testsanitizers/cc_test.go b/libgo/misc/cgo/testsanitizers/cc_test.go
index 0192a663ddd..384b6250e1e 100644
--- a/libgo/misc/cgo/testsanitizers/cc_test.go
+++ b/libgo/misc/cgo/testsanitizers/cc_test.go
@@ -11,7 +11,6 @@ import (
 	"encoding/json"
 	"errors"
 	"fmt"
-	"io/ioutil"
 	"os"
 	"os/exec"
 	"path/filepath"
@@ -36,7 +35,7 @@ func requireOvercommit(t *testing.T) {
 
 	overcommit.Once.Do(func() {
 		var out []byte
-		out, overcommit.err = ioutil.ReadFile("/proc/sys/vm/overcommit_memory")
+		out, overcommit.err = os.ReadFile("/proc/sys/vm/overcommit_memory")
 		if overcommit.err != nil {
 			return
 		}
@@ -313,14 +312,14 @@ int main() {
 `)
 
 func (c *config) checkCSanitizer() (skip bool, err error) {
-	dir, err := ioutil.TempDir("", c.sanitizer)
+	dir, err := os.MkdirTemp("", c.sanitizer)
 	if err != nil {
 		return false, fmt.Errorf("failed to create temp directory: %v", err)
 	}
 	defer os.RemoveAll(dir)
 
 	src := filepath.Join(dir, "return0.c")
-	if err := ioutil.WriteFile(src, cMain, 0600); err != nil {
+	if err := os.WriteFile(src, cMain, 0600); err != nil {
 		return false, fmt.Errorf("failed to write C source file: %v", err)
 	}
 
@@ -418,7 +417,7 @@ func (d *tempDir) Join(name string) string {
 
 func newTempDir(t *testing.T) *tempDir {
 	t.Helper()
-	dir, err := ioutil.TempDir("", filepath.Dir(t.Name()))
+	dir, err := os.MkdirTemp("", filepath.Dir(t.Name()))
 	if err != nil {
 		t.Fatalf("Failed to create temp dir: %v", err)
 	}
@@ -440,3 +439,14 @@ func hangProneCmd(name string, arg ...string) *exec.Cmd {
 	}
 	return cmd
 }
+
+// mSanSupported is a copy of the function cmd/internal/sys.MSanSupported,
+// because the internal pacakage can't be used here.
+func mSanSupported(goos, goarch string) bool {
+	switch goos {
+	case "linux":
+		return goarch == "amd64" || goarch == "arm64"
+	default:
+		return false
+	}
+}
diff --git a/libgo/misc/cgo/testsanitizers/cshared_test.go b/libgo/misc/cgo/testsanitizers/cshared_test.go
index 56063ea6201..8fd03715a11 100644
--- a/libgo/misc/cgo/testsanitizers/cshared_test.go
+++ b/libgo/misc/cgo/testsanitizers/cshared_test.go
@@ -6,7 +6,7 @@ package sanitizers_test
 
 import (
 	"fmt"
-	"io/ioutil"
+	"os"
 	"strings"
 	"testing"
 )
@@ -19,6 +19,12 @@ func TestShared(t *testing.T) {
 	if err != nil {
 		t.Fatal(err)
 	}
+
+	GOARCH, err := goEnv("GOARCH")
+	if err != nil {
+		t.Fatal(err)
+	}
+
 	libExt := "so"
 	if GOOS == "darwin" {
 		libExt = "dylib"
@@ -41,6 +47,11 @@ func TestShared(t *testing.T) {
 	for _, tc := range cases {
 		tc := tc
 		name := strings.TrimSuffix(tc.src, ".go")
+		//The memory sanitizer tests require support for the -msan option.
+		if tc.sanitizer == "memory" && !mSanSupported(GOOS, GOARCH) {
+			t.Logf("skipping %s test on %s/%s; -msan option is not supported.", name, GOOS, GOARCH)
+			continue
+		}
 		t.Run(name, func(t *testing.T) {
 			t.Parallel()
 			config := configure(tc.sanitizer)
@@ -53,7 +64,7 @@ func TestShared(t *testing.T) {
 			mustRun(t, config.goCmd("build", "-buildmode=c-shared", "-o", lib, srcPath(tc.src)))
 
 			cSrc := dir.Join("main.c")
-			if err := ioutil.WriteFile(cSrc, cMain, 0600); err != nil {
+			if err := os.WriteFile(cSrc, cMain, 0600); err != nil {
 				t.Fatalf("failed to write C source file: %v", err)
 			}
 
diff --git a/libgo/misc/cgo/testsanitizers/msan_test.go b/libgo/misc/cgo/testsanitizers/msan_test.go
index 5e2f9759bae..2a3494fbfc1 100644
--- a/libgo/misc/cgo/testsanitizers/msan_test.go
+++ b/libgo/misc/cgo/testsanitizers/msan_test.go
@@ -10,6 +10,19 @@ import (
 )
 
 func TestMSAN(t *testing.T) {
+	goos, err := goEnv("GOOS")
+	if err != nil {
+		t.Fatal(err)
+	}
+	goarch, err := goEnv("GOARCH")
+	if err != nil {
+		t.Fatal(err)
+	}
+	// The msan tests require support for the -msan option.
+	if !mSanSupported(goos, goarch) {
+		t.Skipf("skipping on %s/%s; -msan option is not supported.", goos, goarch)
+	}
+
 	t.Parallel()
 	requireOvercommit(t)
 	config := configure("memory")
diff --git a/libgo/misc/cgo/testsanitizers/testdata/tsan9.go b/libgo/misc/cgo/testsanitizers/testdata/tsan9.go
index f166d8b495a..06304be751b 100644
--- a/libgo/misc/cgo/testsanitizers/testdata/tsan9.go
+++ b/libgo/misc/cgo/testsanitizers/testdata/tsan9.go
@@ -44,7 +44,7 @@ void spin() {
 import "C"
 
 import (
-	"io/ioutil"
+	"io"
 	"runtime/pprof"
 	"time"
 )
@@ -60,7 +60,7 @@ func goSpin() {
 }
 
 func main() {
-	pprof.StartCPUProfile(ioutil.Discard)
+	pprof.StartCPUProfile(io.Discard)
 	go C.spin()
 	goSpin()
 	pprof.StopCPUProfile()
diff --git a/libgo/misc/cgo/testshared/shared_test.go b/libgo/misc/cgo/testshared/shared_test.go
index f52391c6f6c..e77f8489154 100644
--- a/libgo/misc/cgo/testshared/shared_test.go
+++ b/libgo/misc/cgo/testshared/shared_test.go
@@ -13,7 +13,6 @@ import (
 	"fmt"
 	"go/build"
 	"io"
-	"io/ioutil"
 	"log"
 	"os"
 	"os/exec"
@@ -90,7 +89,7 @@ func goCmd(t *testing.T, args ...string) string {
 
 // TestMain calls testMain so that the latter can use defer (TestMain exits with os.Exit).
 func testMain(m *testing.M) (int, error) {
-	workDir, err := ioutil.TempDir("", "shared_test")
+	workDir, err := os.MkdirTemp("", "shared_test")
 	if err != nil {
 		return 0, err
 	}
@@ -177,7 +176,7 @@ func cloneTestdataModule(gopath string) (string, error) {
 	if err := overlayDir(modRoot, "testdata"); err != nil {
 		return "", err
 	}
-	if err := ioutil.WriteFile(filepath.Join(modRoot, "go.mod"), []byte("module testshared\n"), 0644); err != nil {
+	if err := os.WriteFile(filepath.Join(modRoot, "go.mod"), []byte("module testshared\n"), 0644); err != nil {
 		return "", err
 	}
 	return modRoot, nil
@@ -318,7 +317,7 @@ func TestShlibnameFiles(t *testing.T) {
 	}
 	for _, pkg := range pkgs {
 		shlibnamefile := filepath.Join(gorootInstallDir, pkg+".shlibname")
-		contentsb, err := ioutil.ReadFile(shlibnamefile)
+		contentsb, err := os.ReadFile(shlibnamefile)
 		if err != nil {
 			t.Errorf("error reading shlibnamefile for %s: %v", pkg, err)
 			continue
@@ -791,7 +790,7 @@ func resetFileStamps() {
 // It also sets the time of the file, so that we can see if it is rewritten.
 func touch(t *testing.T, path string) (cleanup func()) {
 	t.Helper()
-	data, err := ioutil.ReadFile(path)
+	data, err := os.ReadFile(path)
 	if err != nil {
 		t.Fatal(err)
 	}
@@ -837,14 +836,14 @@ func touch(t *testing.T, path string) (cleanup func()) {
 	// user-writable.
 	perm := fi.Mode().Perm() | 0200
 
-	if err := ioutil.WriteFile(path, data, perm); err != nil {
+	if err := os.WriteFile(path, data, perm); err != nil {
 		t.Fatal(err)
 	}
 	if err := os.Chtimes(path, nearlyNew, nearlyNew); err != nil {
 		t.Fatal(err)
 	}
 	return func() {
-		if err := ioutil.WriteFile(path, old, perm); err != nil {
+		if err := os.WriteFile(path, old, perm); err != nil {
 			t.Fatal(err)
 		}
 	}
diff --git a/libgo/misc/cgo/testshared/testdata/depBase/asm.s b/libgo/misc/cgo/testshared/testdata/depBase/asm.s
index a8acf77f0b9..0f1111f3927 100644
--- a/libgo/misc/cgo/testshared/testdata/depBase/asm.s
+++ b/libgo/misc/cgo/testshared/testdata/depBase/asm.s
@@ -2,7 +2,7 @@
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
-// +build !gccgo
+// +build gc
 
 #include "textflag.h"
 
diff --git a/libgo/misc/cgo/testshared/testdata/depBase/stubs.go b/libgo/misc/cgo/testshared/testdata/depBase/stubs.go
index 04534f38ddd..c77953803bd 100644
--- a/libgo/misc/cgo/testshared/testdata/depBase/stubs.go
+++ b/libgo/misc/cgo/testshared/testdata/depBase/stubs.go
@@ -2,7 +2,7 @@
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
-// +build !gccgo
+// +build gc
 
 package depBase
 
diff --git a/libgo/misc/cgo/testso/so_test.go b/libgo/misc/cgo/testso/so_test.go
index 57f0fd34f78..6d14e32dc6c 100644
--- a/libgo/misc/cgo/testso/so_test.go
+++ b/libgo/misc/cgo/testso/so_test.go
@@ -2,12 +2,12 @@
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
+//go:build cgo
 // +build cgo
 
 package so_test
 
 import (
-	"io/ioutil"
 	"log"
 	"os"
 	"os/exec"
@@ -37,7 +37,7 @@ func requireTestSOSupported(t *testing.T) {
 func TestSO(t *testing.T) {
 	requireTestSOSupported(t)
 
-	GOPATH, err := ioutil.TempDir("", "cgosotest")
+	GOPATH, err := os.MkdirTemp("", "cgosotest")
 	if err != nil {
 		log.Fatal(err)
 	}
@@ -47,7 +47,7 @@ func TestSO(t *testing.T) {
 	if err := overlayDir(modRoot, "testdata"); err != nil {
 		log.Panic(err)
 	}
-	if err := ioutil.WriteFile(filepath.Join(modRoot, "go.mod"), []byte("module cgosotest\n"), 0666); err != nil {
+	if err := os.WriteFile(filepath.Join(modRoot, "go.mod"), []byte("module cgosotest\n"), 0666); err != nil {
 		log.Panic(err)
 	}
 
@@ -80,6 +80,10 @@ func TestSO(t *testing.T) {
 	case "windows":
 		ext = "dll"
 		args = append(args, "-DEXPORT_DLL")
+		// At least in mingw-clang it is not permitted to just name a .dll
+		// on the command line. You must name the corresponding import
+		// library instead, even though the dll is used when the executable is run.
+		args = append(args, "-Wl,-out-implib,libcgosotest.a")
 	case "aix":
 		ext = "so.1"
 	}
diff --git a/libgo/misc/cgo/testso/testdata/cgoso.go b/libgo/misc/cgo/testso/testdata/cgoso.go
index bba5de33121..b59b2a8e8b1 100644
--- a/libgo/misc/cgo/testso/testdata/cgoso.go
+++ b/libgo/misc/cgo/testso/testdata/cgoso.go
@@ -14,7 +14,7 @@ package cgosotest
 #cgo solaris LDFLAGS: -L. -lcgosotest
 #cgo netbsd LDFLAGS: -L. libcgosotest.so
 #cgo darwin LDFLAGS: -L. libcgosotest.dylib
-#cgo windows LDFLAGS: -L. libcgosotest.dll
+#cgo windows LDFLAGS: -L. libcgosotest.a
 #cgo aix LDFLAGS: -L. -l cgosotest
 
 void init(void);
diff --git a/libgo/misc/cgo/testsovar/so_test.go b/libgo/misc/cgo/testsovar/so_test.go
index 57f0fd34f78..6d14e32dc6c 100644
--- a/libgo/misc/cgo/testsovar/so_test.go
+++ b/libgo/misc/cgo/testsovar/so_test.go
@@ -2,12 +2,12 @@
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
+//go:build cgo
 // +build cgo
 
 package so_test
 
 import (
-	"io/ioutil"
 	"log"
 	"os"
 	"os/exec"
@@ -37,7 +37,7 @@ func requireTestSOSupported(t *testing.T) {
 func TestSO(t *testing.T) {
 	requireTestSOSupported(t)
 
-	GOPATH, err := ioutil.TempDir("", "cgosotest")
+	GOPATH, err := os.MkdirTemp("", "cgosotest")
 	if err != nil {
 		log.Fatal(err)
 	}
@@ -47,7 +47,7 @@ func TestSO(t *testing.T) {
 	if err := overlayDir(modRoot, "testdata"); err != nil {
 		log.Panic(err)
 	}
-	if err := ioutil.WriteFile(filepath.Join(modRoot, "go.mod"), []byte("module cgosotest\n"), 0666); err != nil {
+	if err := os.WriteFile(filepath.Join(modRoot, "go.mod"), []byte("module cgosotest\n"), 0666); err != nil {
 		log.Panic(err)
 	}
 
@@ -80,6 +80,10 @@ func TestSO(t *testing.T) {
 	case "windows":
 		ext = "dll"
 		args = append(args, "-DEXPORT_DLL")
+		// At least in mingw-clang it is not permitted to just name a .dll
+		// on the command line. You must name the corresponding import
+		// library instead, even though the dll is used when the executable is run.
+		args = append(args, "-Wl,-out-implib,libcgosotest.a")
 	case "aix":
 		ext = "so.1"
 	}
diff --git a/libgo/misc/cgo/testsovar/testdata/cgoso.go b/libgo/misc/cgo/testsovar/testdata/cgoso.go
index 9c7f95e92ea..d9deb556da8 100644
--- a/libgo/misc/cgo/testsovar/testdata/cgoso.go
+++ b/libgo/misc/cgo/testsovar/testdata/cgoso.go
@@ -18,7 +18,7 @@ package cgosotest
 #cgo solaris LDFLAGS: -L. -lcgosotest
 #cgo netbsd LDFLAGS: -L. libcgosotest.so
 #cgo darwin LDFLAGS: -L. libcgosotest.dylib
-#cgo windows LDFLAGS: -L. libcgosotest.dll
+#cgo windows LDFLAGS: -L. libcgosotest.a
 #cgo aix LDFLAGS: -L. -l cgosotest
 
 #include "cgoso_c.h"