Bug 5850 – Default arguments of out and ref arguments

This D2 program compiles with no errors and runs raising no assert errors: void foo(out int x=1, ref int y=2) {} void main() { int x, y; foo(x, y); assert(x == 0 && y == 0); } If default arguments for out and ref arguments can't be made to work, then I suggest to disallow them statically. In Ada (2012) "A default_expression is only allowed in a parameter_specification for a formal parameter of mode in." See point 19 here: http://www.ada-auth.org/standards/12rm/html/RM-6-1.html

This is related to Issue 7603. Not that your sample won't compile anymore. What will compile is this: int outerX = 1; int outerY; void foo(out int x = outerX, ref int y = outerY) { y = 2; } void main() { int innerX, innerY; foo(innerX, innerY); assert(innerX == 0 && innerY == 2); assert(outerX == 1 && outerY == 0); foo(); assert(outerX == 0 && outerY == 2); } So 'out' and 'ref' default arguments refer to what variables are referenced, not what values are written. Maybe you should open a documentation enhancement request so the above is added to the docs to clear out any confusion for newbies. *** This issue has been marked as a duplicate of issue 7603 ***