On 10/11/2017 03:57 AM, Martin Sebor wrote: > > > Incidentally, void(*)(void) in C++ is a poor choice for this > use case also because of the language's default function > arguments. It's an easy mistake for a C++ programmer to make > to assume that given, say: > > void foo (const char *s = "..."); > > or for any other function that provides default values for all > its arguments, the function may be callable via void(*)(void): > > typedef void F (void); > > void (pf)(void) = (F*)foo;
I'd think it'd be much more common to write instead: typedef void F (void); F *pf = (F*)foo; I.e., use the typedef on both sides of the assignment. > > by having the (default) function argument value(s) magically > substituted at the call site of: > > pf (); > > Bu since that's not the case it would be helpful for the new > warning to detect this mistake. By encouraging the use of > > typedef void F (...); > > as the type of a pointer there is little chance of making such > a mistake. (and then) I don't think I understand this rationale. If users follow the advice, they'll end up with: void foo (const char *s = "..."); typedef void F (...); F *pf = (F *)foo; pf (); which still compiles silently and calls the foo function incorrectly. Thanks, Pedro Alves
