Fix incorrect invocation of JSClassCreate

Reviewed By: kathryngray

Differential Revision: D5465118

fbshipit-source-id: 16e1a1af52fb1ef41fa02e380223e9e90c0611ba

ReactCommon/jschelpers/JSCHelpers.cpp

@@ -31,9 +31,11 @@ JSValueRef functionCaller(
 JSClassRef createFuncClass(JSContextRef ctx) {
   JSClassDefinition definition = kJSClassDefinitionEmpty;
   definition.attributes |= kJSClassAttributeNoAutomaticPrototype;
+
   // Need to duplicate the two different finalizer blocks, since there's no way
   // for it to capture this static information.
-  if (isCustomJSCPtr(ctx)) {
+  const bool isCustomJSC = isCustomJSCPtr(ctx);
+  if (isCustomJSC) {
     definition.finalize = [](JSObjectRef object) {
       auto* function = static_cast<JSFunction*>(JSC_JSObjectGetPrivate(true, object));
       delete function;
@@ -46,7 +48,7 @@ JSClassRef createFuncClass(JSContextRef ctx) {
   }
   definition.callAsFunction = exceptionWrapMethod<&functionCaller>();
 
-  return JSC_JSClassCreate(ctx, &definition);
+  return JSC_JSClassCreate(isCustomJSC, &definition);
 }
 
 JSObjectRef makeFunction(

ReactCommon/jschelpers/JavaScriptCore.h

@@ -31,8 +31,10 @@
 
 // Use for methods were access to a JSContextRef is impractical. The first bool param
 // will be dropped before the JSC method is invoked.
+#define __jsc_ensure_bool(field) \
+  static_assert(std::is_same<typename std::decay<decltype(field)>::type, bool>::value, "useCustomJSC must be bool");
 #define __jsc_bool_wrapper(method, useCustomJSC, ...)    \
-  (useCustomJSC ?                                     \
+  ([]{ __jsc_ensure_bool(useCustomJSC) }, useCustomJSC ? \
     facebook::react::customJSCWrapper() :                \
     facebook::react::systemJSCWrapper()                  \
   )->method(__VA_ARGS__)