Bug 928507: Properly hide JS::Handle's assignment operator; add 'repoint' method to deal with the fallout; fix C1Spewer, IonSpewer, and CompileOptions. r=terrence

js/public/RootingAPI.h

@@ -455,13 +455,16 @@ class MOZ_NONHEAP_CLASS Handle : public js::HandleBase<T>
     bool operator!=(const T &other) const { return *ptr != other; }
     bool operator==(const T &other) const { return *ptr == other; }
 
+    /* Change this handle to point to the same rooted location RHS does. */
+    void repoint(const Handle &rhs) { ptr = rhs.address(); }
+
   private:
     Handle() {}
 
     const T *ptr;
 
-    template <typename S>
-    void operator=(S v) MOZ_DELETE;
+    template <typename S> void operator=(S) MOZ_DELETE;
+    void operator=(Handle) MOZ_DELETE;
 };
 
 /*

js/src/jit/C1Spewer.cpp

@@ -31,7 +31,7 @@ C1Spewer::beginFunction(MIRGraph *graph, HandleScript script)
         return;
 
     this->graph  = graph;
-    this->script = script;
+    this->script.repoint(script);
 
     fprintf(spewout_, "begin_compilation\n");
     if (script) {

js/src/jit/IonSpewer.cpp

@@ -161,7 +161,7 @@ IonSpewer::beginFunction(MIRGraph *graph, HandleScript function)
     }
 
     this->graph = graph;
-    this->function = function;
+    this->function.repoint(function);
 
     c1Spewer.beginFunction(graph, function);
     jsonSpewer.beginFunction(function);

js/src/jsapi.cpp

@@ -4466,7 +4466,7 @@ JS::Compile(JSContext *cx, HandleObject obj, CompileOptions options, const char
     AutoFile file;
     if (!file.open(cx, filename))
         return nullptr;
-    options = options.setFileAndLine(filename, 1);
+    options.setFileAndLine(filename, 1);
     JSScript *script = Compile(cx, obj, options, file.fp());
     return script;
 }

js/src/jsapi.h

@@ -3469,7 +3469,7 @@ class JS_PUBLIC_API(CompileOptions)
     }
     CompileOptions &setSourceMapURL(const jschar *s) { sourceMapURL = s; return *this; }
     CompileOptions &setColumn(unsigned c) { column = c; return *this; }
-    CompileOptions &setElement(Handle<JSObject*> e) { element = e; return *this; }
+    CompileOptions &setElement(Handle<JSObject*> e) { element.repoint(e); return *this; }
     CompileOptions &setCompileAndGo(bool cng) { compileAndGo = cng; return *this; }
     CompileOptions &setForEval(bool eval) { forEval = eval; return *this; }
     CompileOptions &setNoScriptRval(bool nsr) { noScriptRval = nsr; return *this; }