https://gcc.gnu.org/bugzilla/show_bug.cgi?id=113450
--- Comment #15 from Jonathan Wakely <redi at gcc dot gnu.org> --- (In reply to r...@cebitec.uni-bielefeld.de from comment #14) > Further research has uncovered some interesting facts: > > * Neither the SysV SPARC psABI (3rd Edition, 1996) nor the original i386 > psABI (4th Edition, 1997) specify int8_t at all. Actually no wonder > because both predate C99. > > However, even the current Intel386 psABI 1.1 (2015) has nothing here, > nor does the AMD64 psABI 1.0 (2024). > > To my astonishment however, the SPARC Compliance Definition 2.4.1 > (1999), defacto if not in name the SPARC V9 psABI, lists in Figure > 6-140: <inttypes.h>, p.6P-13: > > typedef signed char int8_t; > > So it seems at least Solaris/SPARCV9 violates its own ABI ;-( Ouch! > * When checking clang, there were more surprises: > > #define __INT8_TYPE__ signed char > > With very few exceptions, clang uses the default definitions of the > intN_t types everywhere. That's interesting. I think GCC defines those __INTn_TYPE__ macros after inspecting the target headers (assuming the target provides <stdint.h> or <inttypes.h>) to ensure they agree. I wonder if Clang intentionally deviated from the Solaris headers to "fix" this issue, or if they just define __INT8_TYPE__ to signed char for all 8-bit targets because "obviously" that's correct for all targets (even though it isn't actually correct for Solaris). That means GCC and Clang will disagree about the mangling of a C++ function like void foo(int8_t); > However, the question remains how much that counts: given clang/llvm > has seen years of neglect on Solaris, I wonder how much actual code is > really built with it on Solaris. > > * The Oracle Studio 12.6 cc has no definition of __INT8_TYPE__ at all > AFAICT. If that's true, one could change the type's definition simply > by adjusting <sys/int_types.h>, which would be nice and easy. I think those macros are a GCC thing not required by any standard. Oracle Studio can just rely on <stdint.h> being present, because they know that's true for Solaris. GCC can't (or couldn't historically) rely on <stdint.h> being present for all targets so needed some other way to make those types available. Thanks for digging into this!
