Bug 647011: Sprinkle some DebugOnly in js/src. r=luke

js/src/jscntxt.cpp

@@ -1000,10 +1000,7 @@ js_DestroyContext(JSContext *cx, JSDestroyContextMode mode)
              * JSCONTEXT_DESTROY callback is not allowed to fail and must
              * return true.
              */
-#ifdef DEBUG
-            JSBool callbackStatus =
-#endif
-            cxCallback(cx, JSCONTEXT_DESTROY);
+            DebugOnly<JSBool> callbackStatus = cxCallback(cx, JSCONTEXT_DESTROY);
             JS_ASSERT(callbackStatus);
         }
     }

js/src/jscntxt.h

@@ -2510,10 +2510,8 @@ class AutoEnumStateRooter : private AutoGCRooter
 
     ~AutoEnumStateRooter() {
         if (!stateValue.isNull()) {
-#ifdef DEBUG
-            JSBool ok =
-#endif
-            obj->enumerate(context, JSENUMERATE_DESTROY, &stateValue, 0);
+            DebugOnly<JSBool> ok =
+                obj->enumerate(context, JSENUMERATE_DESTROY, &stateValue, 0);
             JS_ASSERT(ok);
         }
     }

js/src/jsemit.cpp

@@ -850,9 +850,7 @@ OptimizeSpanDeps(JSContext *cx, JSCodeGenerator *cg)
     JSSrcNoteSpec *spec;
     uintN i, n, noteIndex;
     JSTryNode *tryNode;
-#ifdef DEBUG_brendan
-    int passes = 0;
-#endif
+    DebugOnly<int> passes = 0;
 
     base = CG_BASE(cg);
     sdbase = cg->spanDeps;
@@ -4694,10 +4692,7 @@ js_EmitTree(JSContext *cx, JSCodeGenerator *cg, JSParseNode *pn)
             if (!EmitFunctionDefNop(cx, cg, index))
                 return JS_FALSE;
         } else {
-#ifdef DEBUG
-            BindingKind kind =
-#endif
-                cg->bindings.lookup(cx, fun->atom, &slot);
+            DebugOnly<BindingKind> kind = cg->bindings.lookup(cx, fun->atom, &slot);
             JS_ASSERT(kind == VARIABLE || kind == CONSTANT);
             JS_ASSERT(index < JS_BIT(20));
             pn->pn_index = index;

js/src/jsobj.cpp

@@ -4798,9 +4798,7 @@ js_DefineNativeProperty(JSContext *cx, JSObject *obj, jsid id, const Value &valu
          * See bug 560998.
          */
         if (obj->shape() == oldShape && obj->branded() && shape->slot != SHAPE_INVALID_SLOT) {
-#ifdef DEBUG
-            const Shape *newshape =
-#endif
+            DebugOnly<const Shape*> newshape =
                 obj->methodWriteBarrier(cx, *shape, valueCopy);
             JS_ASSERT(newshape == shape);
         }
@@ -5154,9 +5152,7 @@ js_FindIdentifierBase(JSContext *cx, JSObject *scopeChain, jsid id)
                 return obj;
             }
             JS_ASSERT_IF(obj->getParent(), pobj->getClass() == obj->getClass());
-#ifdef DEBUG
-            PropertyCacheEntry *entry =
-#endif
+            DebugOnly<PropertyCacheEntry*> entry =
                 JS_PROPERTY_CACHE(cx).fill(cx, scopeChain, scopeIndex, protoIndex, pobj,
                                            (Shape *) prop);
             JS_ASSERT(entry);

js/src/jsscript.cpp

@@ -265,10 +265,7 @@ Bindings::sharpSlotBase(JSContext *cx)
 #if JS_HAS_SHARP_VARS
     if (JSAtom *name = js_Atomize(cx, "#array", 6, 0)) {
         uintN index = uintN(-1);
-#ifdef DEBUG
-        BindingKind kind =
-#endif
-            lookup(cx, name, &index);
+        DebugOnly<BindingKind> kind = lookup(cx, name, &index);
         JS_ASSERT(kind == VARIABLE);
         return int(index);
     }

js/src/jstracer.cpp

@@ -6607,14 +6607,9 @@ ExecuteTree(JSContext* cx, TraceMonitor* tm, TreeFragment* f, uintN& inlineCallC
     JS_ASSERT_IF(lr->exitType == LOOP_EXIT, !lr->calldepth);
 
     /* Restore interpreter state. */
-#ifdef DEBUG
-    LEAVE_TREE_STATUS lts = 
-#endif
-        LeaveTree(tm, state, lr);
-#ifdef DEBUG
+    DebugOnly<LEAVE_TREE_STATUS> lts = LeaveTree(tm, state, lr);
     JS_ASSERT_IF(lts == NO_DEEP_BAIL,
                  *(uint64*)&tm->storage->global()[globalSlots] == 0xdeadbeefdeadbeefLL);
-#endif
 
     *lrp = state.innermost;
     bool ok = !(state.builtinStatus & BUILTIN_ERROR);
@@ -6927,10 +6922,7 @@ LeaveTree(TraceMonitor *tm, TracerState& state, VMSideExit* lr)
                       calldepth,
                       (unsigned long long int)cycles);
 
-#ifdef DEBUG
-    int slots =
-#endif
-        FlushNativeStackFrame(cx, innermost->calldepth, innermost->stackTypeMap(), stack);
+    DebugOnly<int> slots = FlushNativeStackFrame(cx, innermost->calldepth, innermost->stackTypeMap(), stack);
     JS_ASSERT(unsigned(slots) == innermost->numStackSlots);
 
     /*
@@ -6963,10 +6955,7 @@ LeaveTree(TraceMonitor *tm, TracerState& state, VMSideExit* lr)
         JS_ASSERT(innermost->root()->nGlobalTypes() == ngslots);
         JS_ASSERT(innermost->root()->nGlobalTypes() > innermost->numGlobalSlots);
         typeMap.ensure(ngslots);
-#ifdef DEBUG
-        unsigned check_ngslots =
-#endif
-        BuildGlobalTypeMapFromInnerTree(typeMap, innermost);
+        DebugOnly<unsigned> check_ngslots = BuildGlobalTypeMapFromInnerTree(typeMap, innermost);
         JS_ASSERT(check_ngslots == ngslots);
         globalTypeMap = typeMap.data();
     }
@@ -8135,9 +8124,7 @@ TraceRecorder::callProp(JSObject* obj, JSProperty* prop, jsid id, Value*& vp,
         // Call objects do not yet have shape->isMethod() properties, but they
         // should. See bug 514046, for which this code is future-proof. Remove
         // this comment when that bug is fixed (so, FIXME: 514046).
-#ifdef DEBUG
-        JSBool rv =
-#endif
+        DebugOnly<JSBool> rv =
             js_GetPropertyHelper(cx, obj, shape->id,
                                  (op == JSOP_CALLNAME)
                                  ? JSGET_NO_METHOD_BARRIER

js/src/jsutil.h

@@ -45,6 +45,7 @@
 #define jsutil_h___
 
 #include "jstypes.h"
+#include "mozilla/Util.h"
 #include <stdlib.h>
 #include <string.h>
 
@@ -463,6 +464,9 @@ JS_END_EXTERN_C
  * be used, though this is undesirable.
  */
 namespace js {
+/* Import common mfbt declarations into "js". */
+using namespace mozilla;
+
 class OffTheBooks {
 public:
     JS_DECLARE_NEW_METHODS(::js_malloc, JS_ALWAYS_INLINE static)

js/src/shell/js.cpp

@@ -4153,9 +4153,7 @@ WatchdogMain(void *arg)
             PRIntervalTime sleepDuration = gWatchdogHasTimeout
                                            ? gWatchdogTimeout - now
                                            : PR_INTERVAL_NO_TIMEOUT;
-#ifdef DEBUG
-            PRStatus status =
-#endif
+            DebugOnly<PRStatus> status =
                 PR_WaitCondVar(gWatchdogWakeup, sleepDuration);
             JS_ASSERT(status == PR_SUCCESS);
         }

mfbt/Util.h

@@ -40,6 +40,8 @@
 #ifndef mozilla_Util_h_
 #define mozilla_Util_h_
 
+#ifdef __cplusplus
+
 namespace mozilla {
 
 /**
@@ -81,12 +83,16 @@ struct DebugOnly
     DebugOnly& operator=(const T&) {}   
 #endif
 
-    // DebugOnly must always have a destructor or else it will
-    // generate "unused variable" warnings, exactly what it's intended
-    // to avoid!
+    /*
+     * DebugOnly must always have a destructor or else it will
+     * generate "unused variable" warnings, exactly what it's intended
+     * to avoid!
+     */
     ~DebugOnly() {}
 };
 
-} // namespace mozilla
+} /* namespace mozilla */
 
-#endif  // mozilla_Util_h_
+#endif /* __cplusplus */
+
+#endif  /* mozilla_Util_h_ */