libgo: update to go1.15rc1

Reviewed-on: https://go-review.googlesource.com/c/gofrontend/+/245157

3 files changed, 33 insertions, 16 deletions

diff --git a/libgo/go/syscall/js/func.go b/libgo/go/syscall/js/func.go
index 6c145c9..da4cf68 100644
--- a/libgo/go/syscall/js/func.go
+++ b/libgo/go/syscall/js/func.go
@@ -22,19 +22,24 @@ type Func struct {
 	id    uint32
 }
 
-// FuncOf returns a wrapped function.
+// FuncOf returns a function to be used by JavaScript.
 //
-// Invoking the JavaScript function will synchronously call the Go function fn with the value of JavaScript's
-// "this" keyword and the arguments of the invocation.
-// The return value of the invocation is the result of the Go function mapped back to JavaScript according to ValueOf.
+// The Go function fn is called with the value of JavaScript's "this" keyword and the
+// arguments of the invocation. The return value of the invocation is
+// the result of the Go function mapped back to JavaScript according to ValueOf.
 //
-// A wrapped function triggered during a call from Go to JavaScript gets executed on the same goroutine.
-// A wrapped function triggered by JavaScript's event loop gets executed on an extra goroutine.
-// Blocking operations in the wrapped function will block the event loop.
-// As a consequence, if one wrapped function blocks, other wrapped funcs will not be processed.
-// A blocking function should therefore explicitly start a new goroutine.
+// Invoking the wrapped Go function from JavaScript will
+// pause the event loop and spawn a new goroutine.
+// Other wrapped functions which are triggered during a call from Go to JavaScript
+// get executed on the same goroutine.
 //
-// Func.Release must be called to free up resources when the function will not be used any more.
+// As a consequence, if one wrapped function blocks, JavaScript's event loop
+// is blocked until that function returns. Hence, calling any async JavaScript
+// API, which requires the event loop, like fetch (http.Client), will cause an
+// immediate deadlock. Therefore a blocking function should explicitly start a
+// new goroutine.
+//
+// Func.Release must be called to free up resources when the function will not be invoked any more.
 func FuncOf(fn func(this Value, args []Value) interface{}) Func {
 	funcsMu.Lock()
 	id := nextFuncID
@@ -49,6 +54,7 @@ func FuncOf(fn func(this Value, args []Value) interface{}) Func {
 
 // Release frees up resources allocated for the function.
 // The function must not be invoked after calling Release.
+// It is allowed to call Release while the function is still running.
 func (c Func) Release() {
 	funcsMu.Lock()
 	delete(funcs, c.id)
diff --git a/libgo/go/syscall/js/js.go b/libgo/go/syscall/js/js.go
index 8a04399..a48bbd4 100644
--- a/libgo/go/syscall/js/js.go
+++ b/libgo/go/syscall/js/js.go
@@ -565,28 +565,28 @@ func (e *ValueError) Error() string {
 	return "syscall/js: call of " + e.Method + " on " + e.Type.String()
 }
 
-// CopyBytesToGo copies bytes from the Uint8Array src to dst.
+// CopyBytesToGo copies bytes from src to dst.
+// It panics if src is not an Uint8Array or Uint8ClampedArray.
 // It returns the number of bytes copied, which will be the minimum of the lengths of src and dst.
-// CopyBytesToGo panics if src is not an Uint8Array.
 func CopyBytesToGo(dst []byte, src Value) int {
 	n, ok := copyBytesToGo(dst, src.ref)
 	runtime.KeepAlive(src)
 	if !ok {
-		panic("syscall/js: CopyBytesToGo: expected src to be an Uint8Array")
+		panic("syscall/js: CopyBytesToGo: expected src to be an Uint8Array or Uint8ClampedArray")
 	}
 	return n
 }
 
 func copyBytesToGo(dst []byte, src ref) (int, bool)
 
-// CopyBytesToJS copies bytes from src to the Uint8Array dst.
+// CopyBytesToJS copies bytes from src to dst.
+// It panics if dst is not an Uint8Array or Uint8ClampedArray.
 // It returns the number of bytes copied, which will be the minimum of the lengths of src and dst.
-// CopyBytesToJS panics if dst is not an Uint8Array.
 func CopyBytesToJS(dst Value, src []byte) int {
 	n, ok := copyBytesToJS(dst.ref, src)
 	runtime.KeepAlive(dst)
 	if !ok {
-		panic("syscall/js: CopyBytesToJS: expected dst to be an Uint8Array")
+		panic("syscall/js: CopyBytesToJS: expected dst to be an Uint8Array or Uint8ClampedArray")
 	}
 	return n
 }
diff --git a/libgo/go/syscall/js/js_test.go b/libgo/go/syscall/js/js_test.go
index fea4c13..5fc9107 100644
--- a/libgo/go/syscall/js/js_test.go
+++ b/libgo/go/syscall/js/js_test.go
@@ -591,3 +591,14 @@ func BenchmarkDOM(b *testing.B) {
 		document.Get("body").Call("removeChild", div)
 	}
 }
+
+func TestGlobal(t *testing.T) {
+	ident := js.FuncOf(func(this js.Value, args []js.Value) interface{} {
+		return args[0]
+	})
+	defer ident.Release()
+
+	if got := ident.Invoke(js.Global()); !got.Equal(js.Global()) {
+		t.Errorf("got %#v, want %#v", got, js.Global())
+	}
+}