On 11/01/16 22:31, Jason Merrill wrote: > On Tue, Nov 1, 2016 at 4:00 PM, Bernd Edlinger > <bernd.edlin...@hotmail.de> wrote: >> On 11/01/16 20:48, Jason Merrill wrote: >>>>>>>> else if ((DECL_EXTERN_C_P (newdecl) >>>>>>>> && DECL_EXTERN_C_P (olddecl)) >>>>>>>> || compparms (TYPE_ARG_TYPES (TREE_TYPE (newdecl)), >>>>>>>> TYPE_ARG_TYPES (TREE_TYPE (olddecl)))) >>>>> >>>>> So I was thinking to drop the "else" and the compparms test. >>>> >>>> Yes. But then we must somehow avoid: >>>> >>>> else >>>> /* Discard the old built-in function. */ >>>> return NULL_TREE; > >>>> It maybe easier, just to copy the warning to the DECL_ANTICIPATED case? >>> >>> Or even move it there; removing the existing warning doesn't change >>> anything in the testsuite, and I'm having trouble imagining how to >>> trigger it. >>> >> >> Nice. It must be something, which does not anticipate a declaration. >> >> like: >> >> cat test.cc >> int __builtin_abort(void*); >> >> g++ -c test.cc >> test.cc:1:5: warning: new declaration 'int __builtin_abort(void*)' >> ambiguates built-in declaration 'void __builtin_abort()' >> int __builtin_abort(void*); >> ^~~~~~~~~~~~~~~ >> >> Intersting, the warning comes even though I forgot to add the >> extern "C". > > Looks like anything starting with __builtin is implicitly extern "C" > (set in grokfndecl). >
Oh, Well. we do also have such builtins that begin with __sync_ like extern "C" unsigned char __sync_fetch_and_add_1(volatile void*, unsigned char); > If we remove the DECL_ANTICIPATED check, I see some failures in > builtin* tests due to missing extern "C". That seems appropriate at > file scope, but I'm not sure it's right for namespace std. > Interesting, what have you done? Sounds a bit like the issue I had with the std::abs overloads. To get rid of that I added this in the DECL_ANTICIPATED path: + /* A new declaration doesn't match a built-in one unless it + is also extern "C". */ + gcc_assert (DECL_IS_BUILTIN (olddecl)); + gcc_assert (DECL_EXTERN_C_P (olddecl)); + if (!DECL_EXTERN_C_P (newdecl)) + return NULL_TREE; + Bernd.
