michael@0: /*
michael@0:  * Any copyright is dedicated to the Public Domain.
michael@0:  * http://creativecommons.org/licenses/publicdomain/
michael@0:  */
michael@0: 
michael@0: function make_watcher(name) {
michael@0:     return function (id, oldv, newv) {
michael@0:         print("watched " + name + "[0]");
michael@0:     };
michael@0: }
michael@0: 
michael@0: var o, p;
michael@0: function f(flag) {
michael@0:     if (flag) {
michael@0:         o = arguments;
michael@0:     } else {
michael@0:         p = arguments;
michael@0:         o.watch(0, make_watcher('o'));
michael@0:         p.watch(0, make_watcher('p'));
michael@0: 
michael@0:         /*
michael@0:          * Previously, the watchpoint implementation actually substituted its magic setter
michael@0:          * functions for the setters of shared shapes, and then 1) carefully ignored calls
michael@0:          * to its magic setter from unrelated objects, and 2) avoided restoring the
michael@0:          * original setter until all watchpoints on that shape had been removed.
michael@0:          * 
michael@0:          * However, when the watchpoint code began using JSObject::changeProperty and
michael@0:          * js_ChangeNativePropertyAttrs to change shapes' setters, the shape tree code
michael@0:          * became conscious of the presence of watchpoints, and shared shapes between
michael@0:          * objects only when their watchpoint nature coincided. Clearing the magic setter
michael@0:          * from one object's shape would not affect other objects, because the
michael@0:          * watchpointed and non-watchpointed shapes were distinct if they were shared.
michael@0:          * 
michael@0:          * Thus, the first unwatch call must go ahead and fix p's shape, even though a
michael@0:          * watchpoint exists on the same shape in o. o's watchpoint's presence shouldn't
michael@0:          * cause 'unwatch' to leave p's magic setter in place.
michael@0:          */
michael@0: 
michael@0:         /* DropWatchPointAndUnlock would see o's watchpoint, and not change p's property. */
michael@0:         p.unwatch(0);
michael@0: 
michael@0:         /* DropWatchPointAndUnlock would fix o's property, but not p's; p's setter would be gone. */
michael@0:         o.unwatch(0);
michael@0: 
michael@0:         /* This would fail to invoke the arguments object's setter. */
michael@0:         p[0] = 4;
michael@0: 
michael@0:         /* And the formal parameter would not get updated. */
michael@0:         assertEq(flag, 4);
michael@0:     }
michael@0: }
michael@0: 
michael@0: f(true);
michael@0: f(false);
michael@0: 
michael@0: reportCompare(true, true);