libgo: update to Go1.18beta2

gotools/
	* Makefile.am (go_cmd_cgo_files): Add ast_go118.go
	(check-go-tool): Copy golang.org/x/tools directories.
	* Makefile.in: Regenerate.

Reviewed-on: https://go-review.googlesource.com/c/gofrontend/+/384695

3 files changed, 81 insertions, 19 deletions

diff --git a/libgo/go/context/benchmark_test.go b/libgo/go/context/benchmark_test.go
index 69d75ff..144f473 100644
--- a/libgo/go/context/benchmark_test.go
+++ b/libgo/go/context/benchmark_test.go
@@ -152,3 +152,39 @@ func BenchmarkContextCancelDone(b *testing.B) {
 		}
 	})
 }
+
+func BenchmarkDeepValueNewGoRoutine(b *testing.B) {
+	for _, depth := range []int{10, 20, 30, 50, 100} {
+		ctx := Background()
+		for i := 0; i < depth; i++ {
+			ctx = WithValue(ctx, i, i)
+		}
+
+		b.Run(fmt.Sprintf("depth=%d", depth), func(b *testing.B) {
+			for i := 0; i < b.N; i++ {
+				var wg sync.WaitGroup
+				wg.Add(1)
+				go func() {
+					defer wg.Done()
+					ctx.Value(-1)
+				}()
+				wg.Wait()
+			}
+		})
+	}
+}
+
+func BenchmarkDeepValueSameGoRoutine(b *testing.B) {
+	for _, depth := range []int{10, 20, 30, 50, 100} {
+		ctx := Background()
+		for i := 0; i < depth; i++ {
+			ctx = WithValue(ctx, i, i)
+		}
+
+		b.Run(fmt.Sprintf("depth=%d", depth), func(b *testing.B) {
+			for i := 0; i < b.N; i++ {
+				ctx.Value(-1)
+			}
+		})
+	}
+}
diff --git a/libgo/go/context/context.go b/libgo/go/context/context.go
index 733c5f5..cf010b2 100644
--- a/libgo/go/context/context.go
+++ b/libgo/go/context/context.go
@@ -150,7 +150,7 @@ type Context interface {
 	// 		u, ok := ctx.Value(userKey).(*User)
 	// 		return u, ok
 	// 	}
-	Value(key interface{}) interface{}
+	Value(key any) any
 }
 
 // Canceled is the error returned by Context.Err when the context is canceled.
@@ -182,7 +182,7 @@ func (*emptyCtx) Err() error {
 	return nil
 }
 
-func (*emptyCtx) Value(key interface{}) interface{} {
+func (*emptyCtx) Value(key any) any {
 	return nil
 }
 
@@ -348,11 +348,11 @@ type cancelCtx struct {
 	err      error                 // set to non-nil by the first cancel call
 }
 
-func (c *cancelCtx) Value(key interface{}) interface{} {
+func (c *cancelCtx) Value(key any) any {
 	if key == &cancelCtxKey {
 		return c
 	}
-	return c.Context.Value(key)
+	return value(c.Context, key)
 }
 
 func (c *cancelCtx) Done() <-chan struct{} {
@@ -520,7 +520,7 @@ func WithTimeout(parent Context, timeout time.Duration) (Context, CancelFunc) {
 // interface{}, context keys often have concrete type
 // struct{}. Alternatively, exported context key variables' static
 // type should be a pointer or interface.
-func WithValue(parent Context, key, val interface{}) Context {
+func WithValue(parent Context, key, val any) Context {
 	if parent == nil {
 		panic("cannot create context from nil parent")
 	}
@@ -537,13 +537,13 @@ func WithValue(parent Context, key, val interface{}) Context {
 // delegates all other calls to the embedded Context.
 type valueCtx struct {
 	Context
-	key, val interface{}
+	key, val any
 }
 
 // stringify tries a bit to stringify v, without using fmt, since we don't
 // want context depending on the unicode tables. This is only used by
 // *valueCtx.String().
-func stringify(v interface{}) string {
+func stringify(v any) string {
 	switch s := v.(type) {
 	case stringer:
 		return s.String()
@@ -559,9 +559,35 @@ func (c *valueCtx) String() string {
 		", val " + stringify(c.val) + ")"
 }
 
-func (c *valueCtx) Value(key interface{}) interface{} {
+func (c *valueCtx) Value(key any) any {
 	if c.key == key {
 		return c.val
 	}
-	return c.Context.Value(key)
+	return value(c.Context, key)
+}
+
+func value(c Context, key any) any {
+	for {
+		switch ctx := c.(type) {
+		case *valueCtx:
+			if key == ctx.key {
+				return ctx.val
+			}
+			c = ctx.Context
+		case *cancelCtx:
+			if key == &cancelCtxKey {
+				return c
+			}
+			c = ctx.Context
+		case *timerCtx:
+			if key == &cancelCtxKey {
+				return &ctx.cancelCtx
+			}
+			c = ctx.Context
+		case *emptyCtx:
+			return nil
+		default:
+			return c.Value(key)
+		}
+	}
 }
diff --git a/libgo/go/context/context_test.go b/libgo/go/context/context_test.go
index a2e2324..8673c0f 100644
--- a/libgo/go/context/context_test.go
+++ b/libgo/go/context/context_test.go
@@ -16,21 +16,21 @@ import (
 
 type testingT interface {
 	Deadline() (time.Time, bool)
-	Error(args ...interface{})
-	Errorf(format string, args ...interface{})
+	Error(args ...any)
+	Errorf(format string, args ...any)
 	Fail()
 	FailNow()
 	Failed() bool
-	Fatal(args ...interface{})
-	Fatalf(format string, args ...interface{})
+	Fatal(args ...any)
+	Fatalf(format string, args ...any)
 	Helper()
-	Log(args ...interface{})
-	Logf(format string, args ...interface{})
+	Log(args ...any)
+	Logf(format string, args ...any)
 	Name() string
 	Parallel()
-	Skip(args ...interface{})
+	Skip(args ...any)
 	SkipNow()
-	Skipf(format string, args ...interface{})
+	Skipf(format string, args ...any)
 	Skipped() bool
 }
 
@@ -553,7 +553,7 @@ func testLayers(t testingT, seed int64, testTimeout bool) {
 	t.Parallel()
 
 	r := rand.New(rand.NewSource(seed))
-	errorf := func(format string, a ...interface{}) {
+	errorf := func(format string, a ...any) {
 		t.Errorf(fmt.Sprintf("seed=%d: %s", seed, format), a...)
 	}
 	const (
@@ -691,7 +691,7 @@ func XTestInvalidDerivedFail(t testingT) {
 	}
 }
 
-func recoveredValue(fn func()) (v interface{}) {
+func recoveredValue(fn func()) (v any) {
 	defer func() { v = recover() }()
 	fn()
 	return