Clang's blocks produce atrocious code. Look at the disassembly for: int main(){ __block int (^foo)(int x) = ^ int (int x) { if(x<100) return foo(x+10); ret

Clang's blocks produce atrocious code. Look at the disassembly for: int main(){ __block int (^foo)(int x) = ^ int (int x) { if(x<100) return foo(x+10); return x; }; return foo(69); } versus the GCC: int main(){ int foo(int x) { if(x<100) return foo(x+10); return x; }; return foo(69); } if you want to see what I'm talking about. CLANG: http://pastebin.com/37A9by4V http://pastebin.com/37A9by4V GCC: http://pastebin.com/RMEDnwxi http://pastebin.com/RMEDnwxi However, defer does look interesting, and implementing it for GCC is very easy: #define defer_(x) do{}while(0); \ auto void _dtor1_##x(); \ auto void _dtor2_##x(); \ int __attribute__((cleanup(_dtor2_##x))) _dtorV_##x=69; \ void _dtor2_##x(){if(_dtorV_##x==42)return _dtor1_##x();};_dtorV_##x=42; \ void _dtor1_##x() #define defer__(x) defer_(x) #define defer defer__(__COUNTER__) You don't have to use the stupid block-syntax either, just: in = fopen("whatever", "r"); defer { fclose(in); }