I thought the delegating constructors addition to c++11 was great. Not something I'd need all the time, but it'd probably come in handy once in a while. But as always, there's a hole.

The standard specifies that if a constructor delegates to itself, the program is ill-formed. It also states that in that case no diagnostic is required.
Ref: thenewcpp.wordpress.com

class   C
{
        public:
                C() { }

                C(int aval) : C('i') { }
                C(char) : C(42) { }

} ;

int main(int N, char ** S)
{
        C       test(1) ;

        return 0 ;
}

testerror.cpp:9:13: error: constructor for 'C' creates a delegation cycle [-Wdelegating-ctor-cycles]

                C(char) : C(42) { }
                          ^

testerror.cpp:8:3: note: it delegates to

                C(int aval) : C('i') { }
                ^

testerror.cpp:9:3: note: which delegates to

                C(char) : C(42) { }
                ^

1 error generated.

Labels: c++, c++11, programming