all: Go 1.21 support

src/runtime/baremetal.go

@@ -38,6 +38,8 @@ func growHeap() bool {
 
 //export malloc
 func libc_malloc(size uintptr) unsafe.Pointer {
+	// Note: this zeroes the returned buffer which is not necessary.
+	// The same goes for bytealg.MakeNoZero.
 	return alloc(size, nil)
 }
 

src/runtime/metrics.go

@@ -0,0 +1,10 @@
+package runtime
+
+// Implementation of functions needed by runtime/metrics.
+// Mostly just dummy implementations: we don't currently use any of these
+// metrics.
+
+//go:linkname godebug_registerMetric internal/godebug.registerMetric
+func godebug_registerMetric(name string, read func() uint64) {
+	// Dummy function for compatibility with Go 1.21.
+}

src/runtime/runtime.go

@@ -100,3 +100,27 @@ func godebug_setUpdate(update func(string, string)) {
 	// variable changes (for example, via os.Setenv).
 	godebugUpdate = update
 }
+
+//go:linkname godebug_setNewIncNonDefault internal/godebug.setNewIncNonDefault
+func godebug_setNewIncNonDefault(newIncNonDefault func(string) func()) {
+	// Dummy function necessary in Go 1.21.
+}
+
+// Write to the given file descriptor.
+// This is called from internal/godebug starting with Go 1.21, and only seems to
+// be called with the stderr file descriptor.
+func write(fd uintptr, p unsafe.Pointer, n int32) int32 {
+	if fd == 2 { // stderr
+		// Convert to a string, because we know that p won't change during the
+		// call to printstring.
+		// TODO: use unsafe.String instead once we require Go 1.20.
+		s := _string{
+			ptr:    (*byte)(p),
+			length: uintptr(n),
+		}
+		str := *(*string)(unsafe.Pointer(&s))
+		printstring(str)
+		return n
+	}
+	return 0
+}

src/runtime/runtime_nintendoswitch.go

@@ -105,7 +105,7 @@ func abort() {
 }
 
 //export write
-func write(fd int32, buf *byte, count int) int {
+func libc_write(fd int32, buf *byte, count int) int {
 	// TODO: Proper handling write
 	for i := 0; i < count; i++ {
 		putchar(*buf)

src/runtime/runtime_wasm_js.go

@@ -44,8 +44,8 @@ func nanosecondsToTicks(ns int64) timeUnit {
 // This function is called by the scheduler.
 // Schedule a call to runtime.scheduler, do not actually sleep.
 //
-//export runtime.sleepTicks
+//go:wasmimport gojs runtime.sleepTicks
 func sleepTicks(d timeUnit)
 
-//export runtime.ticks
+//go:wasmimport gojs runtime.ticks
 func ticks() timeUnit

src/runtime/symtab.go

@@ -5,11 +5,14 @@ type Frames struct {
 }
 
 type Frame struct {
+	PC uintptr
+
+	Func *Func
+
 	Function string
 
 	File string
 	Line int
-	PC   uintptr
 }
 
 func CallersFrames(callers []uintptr) *Frames {