runtime, internal/synctest, syscall/js: keep bubble membership in syscalls

Propagate synctest bubble membership through syscall/js.Func
functions. Avoids panics from cross-bubble channel operations
in js syscalls.

Fixes #70512

Change-Id: Idbd9f95da8bc4f055a635dfac041359f848dad1a
Reviewed-on: https://go-review.googlesource.com/c/go/+/631055
Reviewed-by: Michael Pratt <mpratt@google.com>
LUCI-TryBot-Result: Go LUCI <golang-scoped@luci-project-accounts.iam.gserviceaccount.com>
Auto-Submit: Damien Neil <dneil@google.com>

1 files changed, 27 insertions, 0 deletions

diff --git a/src/runtime/synctest.go b/src/runtime/synctest.go
index 0fd5e7873e..09748d5c1c 100644
--- a/src/runtime/synctest.go
+++ b/src/runtime/synctest.go
@@ -270,3 +270,30 @@ func synctestwait_c(gp *g, _ unsafe.Pointer) bool {
 	unlock(&gp.syncGroup.mu)
 	return true
 }
+
+//go:linkname synctest_acquire internal/synctest.acquire
+func synctest_acquire() any {
+	if sg := getg().syncGroup; sg != nil {
+		sg.incActive()
+		return sg
+	}
+	return nil
+}
+
+//go:linkname synctest_release internal/synctest.release
+func synctest_release(sg any) {
+	sg.(*synctestGroup).decActive()
+}
+
+//go:linkname synctest_inBubble internal/synctest.inBubble
+func synctest_inBubble(sg any, f func()) {
+	gp := getg()
+	if gp.syncGroup != nil {
+		panic("goroutine is already bubbled")
+	}
+	gp.syncGroup = sg.(*synctestGroup)
+	defer func() {
+		gp.syncGroup = nil
+	}()
+	f()
+}