diff -r 000000000000 -r 6474c204b198 js/src/gdb/tests/test-Root.cpp
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/js/src/gdb/tests/test-Root.cpp	Wed Dec 31 06:09:35 2014 +0100
@@ -0,0 +1,34 @@
+#include "gdb-tests.h"
+#include "jsapi.h"
+
+FRAGMENT(Root, null) {
+  JS::Rooted<JSObject *> null(cx, nullptr);
+
+  breakpoint();
+
+  (void) null;
+}
+
+void callee(JS::Handle<JSObject *> obj, JS::MutableHandle<JSObject *> mutableObj)
+{
+  // Prevent the linker from unifying this function with others that are
+  // equivalent in machine code but not type.
+  fprintf(stderr, "Called " __FILE__ ":callee\n");
+  breakpoint();
+}
+
+FRAGMENT(Root, handle) {
+  JS::Rooted<JSObject *> global(cx, JS::CurrentGlobalOrNull(cx));
+  callee(global, &global);
+  (void) global;
+}
+
+FRAGMENT(Root, HeapSlot) {
+  JS::Rooted<jsval> plinth(cx, STRING_TO_JSVAL(JS_NewStringCopyZ(cx, "plinth")));
+  JS::Rooted<JSObject *> array(cx, JS_NewArrayObject(cx, plinth));
+
+  breakpoint();
+
+  (void) plinth;
+  (void) array;
+}