diff -r 000000000000 -r 6474c204b198 js/src/gdb/tests/test-jsid.cpp
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/js/src/gdb/tests/test-jsid.cpp	Wed Dec 31 06:09:35 2014 +0100
@@ -0,0 +1,37 @@
+#include "gdb-tests.h"
+#include "jsapi.h"
+
+FRAGMENT(jsid, simple) {
+  JS::Rooted<JSString *> string(cx, JS_NewStringCopyZ(cx, "moon"));
+  JS::Rooted<JSString *> interned(cx, JS_InternJSString(cx, string));
+  JS::Rooted<jsid> string_id(cx, INTERNED_STRING_TO_JSID(cx, interned));
+  jsid int_id = INT_TO_JSID(1729);
+  jsid void_id = JSID_VOID;
+  JS::Rooted<jsid> object_id(cx, OBJECT_TO_JSID(JS::CurrentGlobalOrNull(cx)));
+
+  breakpoint();
+
+  (void) string;
+  (void) interned;
+  (void) string_id;
+  (void) int_id;
+  (void) void_id;
+  (void) object_id;
+}
+
+void
+jsid_handles(JS::Handle<jsid> jsid_handle,
+             JS::MutableHandle<jsid> mutable_jsid_handle)
+{
+  // Prevent the linker from unifying this function with others that are
+  // equivalent in machine code but not type.
+  fprintf(stderr, "Called " __FILE__ ":jsid_handles\n");
+  breakpoint();
+}
+
+FRAGMENT(jsid, handles) {
+  JS::Rooted<JSString *> string(cx, JS_NewStringCopyZ(cx, "shovel"));
+  JS::Rooted<JSString *> interned(cx, JS_InternJSString(cx, string));
+  JS::Rooted<jsid> string_id(cx, INTERNED_STRING_TO_JSID(cx, interned));
+  jsid_handles(string_id, &string_id);
+}