Bug 3366 – Segfault(declaration.c) variadic template with unmatched constraint

> type ice.d class A { void f(T...)() if (T.length != 1){} } void main() { A a = new A; a.f!int(); } > dmd main 2> error.txt // dmd crash >type error.txt //ice.d(3): Error: template ice.A.f(T...) if (T.length != 1) declaration T is already defined

Reduced test case: void f(T...)() if (T.length > 20){} void main(){ f!(int, int)(); } If the tuple length isn't used in the constraint, there's no ICE, but you get the same silly error message about "T is already defined". It only happens if the function has no parameters, and when there is no match. It thinks T is already defined, because in the code which is patched below, it's trying to pass an empty tuple for T. But it's already worked out what T must be (in this case (int, int)). So it gets horribly confused. Root cause: deduceFunctionTemplateMatch() missed this case. PATCH: template.c, deduceFunctionTemplateMatch(), line 885. ---------------- /* Check for match of function arguments with variadic template * parameter, such as: * * template Foo(T, A...) { void Foo(T t, A a); } * void main() { Foo(1,2,3); } */ if (tp) // if variadic { - if (nfparams == 0) // if no function parameters + if (nfparams == 0 && nfargs!=0) // if no function parameters { Tuple *t = new Tuple(); //printf("t = %p\n", t); dedargs->data[parameters->dim - 1] = (void *)t; declareParameter(paramscope, tp, t); goto L2; }

Fixed dmd 1.049 and 2.034