On 6/26/18, Martin Sebor <mse...@gmail.com> wrote: > With the exception of built-ins with the ellipsis (like sprintf), > GCC silently accepts declarations of built-in functions without > prototypes as well as calls to such functions with any numbers > or types of arguments, compatible or otherwise. Calls with > arguments whose number and types match exactly those of > the built-in are considered by the middle-end for optimization. > Other calls (compatible or not, irrespective of whether their > number matches the number expected by the function) are then > made to the library functions. > > Attached is a small fix to -Wbuiltin-declaration-mismatch to > have it diagnose built-in declarations without a prototype. > The warning is enabled by default so it causes a fair number > of tests to fail because of declarations like 'void abort();' > The breakdown of the built-ins behind the test failures is > below. > > Before I take the time to clean up the test suite let me post > what I have in case going this route is not acceptable. As > an alternative, I could try to avoid some of these warnings, > e.g., by diagnosing incompatible calls instead but I think > it's even less worthwhile for built-ins than trying to do > it for ordinary functions with -Wstrict-prototypes. There > is, in my view, no justification today for standard functions > to be declared without a prototype. (I could also make > the warning depend on language mode and -Wpedantic if that > were more preferable.) > > Martin > > About 115 tests fail due to incompatible declarations of > the built-in functions below (the number shows the number > of warnings for each functions): > > 428 abort > 58 exit > 36 memcpy > 17 memmove > 15 realloc > 14 cabs > 5 strncpy > 4 strcmp > 3 alloca > 2 rindex > 1 aligned_alloc >
Could you do something to differentiate it a bit more from the -Wshadow warning that is also touched in this patch? It'd be kind of annoying to get warnings from both flags for the same code...
