Dynamically generated JSExport protocols added to a class results in a crash

[Axel Katerbau]

While the JSExport subprotocol method for exposing methods to JSC works fine when written in Code (as in the examples in Apple's docs), programmatically at runtime generated and added such protocols crash the JSC cocoa bridge.

Run this code to see the crash (I use Xcode 5 release with iOS7 SDK).

@import JavaScriptCore;
@import ObjectiveC;

int main(int argc, char * argv[]) {
    @autoreleasepool {
        JSContext *context = [[JSContext alloc] init];
        Protocol *dynProtocol = objc_allocateProtocol("NSStringJSExport");
        Protocol *jsExportProtocol = @protocol(JSExport);
        protocol_addProtocol(dynProtocol, jsExportProtocol);
        Method method = class_getInstanceMethod([NSString class], @selector(boolValue));
        protocol_addMethodDescription(dynProtocol, @selector(boolValue), method_getTypeEncoding(method), YES, YES);
        //        protocol_addMethodDescription(dynProtocol, @selector(boolValue), "@:", YES, YES); // <-- also crashes
        //        protocol_addMethodDescription(dynProtocol, @selector(boolValue), "B@:", YES, YES); // <-- also crashes
        objc_registerProtocol(dynProtocol);
        class_addProtocol([NSString class], dynProtocol);
        
        context[@"NSString"] = [NSString class]; // <-- crashes here in parseObjCType
        context[@"myString"] = @"YES";
        JSValue *value = [context evaluateScript:@"myResult = myString.boolValue()"];
        NSLog(@"Result = %@", value);
    }
}

[Axel Katerbau]

Created attachment 213680 [details]
Corresponding Xcode project

[Axel Katerbau]

Version used might be:
Mozilla/5.0 (Macintosh; Intel Mac OS X 10_9) AppleWebKit/537.71 (KHTML, like Gecko) Version/7.0 Safari/537.71

[Radar WebKit Bug Importer]

<rdar://problem/15184814>