Bug 5041 – Cannot check functor in template constraint

DMD rejects accessing to a symbol of a function object passed via template alias parameter in template constraints. -------------------- void main() { Fun fun; test!fun(); } struct Fun { int opCall() { return 0; } } void test(alias fun)() if (is(int == typeof(fun()))) // (13) { fun(); } -------------------- % dmd -o- -c test.d test.d(13): Error: function test.test(alias fun) if (is(int == typeof(fun()))).test cannot access frame of function D main test.d(13): Error: function test.test(alias fun) if (is(int == typeof(fun()))).test cannot access frame of function D main test.d(13): Error: function test.test(alias fun) if (is(int == typeof(fun()))).test cannot access frame of function D main test.d(13): Error: function test.test(alias fun) if (is(int == typeof(fun()))).test cannot access frame of function D main -------------------- Passing functor symbols via template alias parameters should be valid like nested functions (see discussion in bug 3051), and actually, it works fine modulo the reported problem. It's a problem of template constraints. -------------------- void main() { Fun fun; test!fun(); assert(fun.value == 123); // okay, passes } struct Fun { int value; void opCall(int a) { value = a; } } void test(alias fun)() { fun(123); }

Works in 2.060head.