On Fri, Jan 8, 2021 at 1:37 PM Jonathan Wakely <jwak...@redhat.com> 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 <stdint.h>, 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__ . Thanks, David
