On 29/04/21 16:06 -0400, David Edelsohn wrote: >On Fri, Jan 8, 2021 at 1:37 PM Jonathan Wakely wrote: >> >> On 06/01/21 19:41 -0500, David Edelsohn wrote: >> >Thanks for clarifying the issue. >> > >> >As you implicitly point out, GCC knows the type of INT64 and defines >> >the macro __INT64_TYPE__ . The revised code can use that directly, >> >such as: >> > >> >#if defined(_GLIBCXX_HAVE_INT64_T_LONG) \ >> > || defined(_GLIBCXX_HAVE_INT64_T_LONG_LONG) >> > typedef __INT64_TYPE__ streamoff; >> > #elif defined(_GLIBCXX_HAVE_INT64_T) >> > typedef int64_t streamoff; >> > #else >> > typedef long long streamoff; >> > #endif >> > >> >Are there any additional issues not addressed by that approach, other >> >than possible further simplification? >> >> That avoids the ABI break that Jakub pointed out. But I think we can >> simplify it further, as in the attached patch. >> >> This uses __INT64_TYPE__ if that's defined, and long long otherwise. I >> think that should be equivalent in all practical cases (I can imagine >> some strange target where __INT64_TYPE__ is defined by the compiler, >> but int64_t isn't defined when the configure checks look for it, and >> so the current code would use long long and with my patch would use >> __INT64_TYPE__ which could be long ... but I think in practice that's >> unlikely. It was probably more likely in older releases where the >> configure test would have been done with -std=gnu++98 and so int64_t >> might not have been declared by libc's , but if that was the >> case then any ABI break it caused happened years ago. > >Hi, Jonathan > >Polite ping. > >Now that GCC 11.1 has been released, can this patch be applied to >libstdc++? As I replied at the time to Jakub's concerns, both Clang >(since 3.0.0) and ICC (since at least 16.0.0) have defined >__INT64_TYPE__ . Pushed to trunk after testing on x86_64-linux and powerpc-aix.