Hi Alex > On 14 Jun 2023, at 14:31, Alex Coplan <alex.cop...@arm.com> wrote: > > Hi, > > This is a v2 patch addressing feedback for: > https://gcc.gnu.org/pipermail/gcc-patches/2023-June/621050.html > > macOS SDK headers using the CF_ENUM macro can expand to invalid C++ code > of the form: > > typedef enum T : BaseType T; > > i.e. an elaborated-type-specifier with an additional enum-base. > Upstream LLVM can be made to accept the above construct with > -Wno-error=elaborated-enum-base. > > This patch adds the -Welaborated-enum-base warning to GCC and adjusts > the C++ parser to emit this warning instead of rejecting this code > outright. > > The macro expansion in the macOS headers occurs in the case that the > compiler declares support for enums with underlying type using > __has_feature, see > https://gcc.gnu.org/pipermail/gcc-patches/2023-May/618450.html > > GCC rejecting this construct outright means that GCC fails to bootstrap > on Darwin in the case that it (correctly) implements __has_feature and > declares support for C++ enums with underlying type. > > With this patch, GCC can bootstrap on Darwin in combination with the > (WIP) __has_feature patch posted at: > https://gcc.gnu.org/pipermail/gcc-patches/2023-May/617878.html > > Bootstrapped/regtested on aarch64-linux-gnu and x86_64-apple-darwin. > OK for trunk?
For the record, I have tried this on Darwin21 and Darwin17 together with my patches for __attribute__((availability(….))) which is also instrumental in exposing more of the SDK content than we have previously been able to parse on GCC. Bootstrap succeeded there, and I will try on some older versions as time permits (likely after WG21 meeting is done). thanks Iain > > Thanks, > Alex > > gcc/c-family/ChangeLog: > > * c.opt (Welaborated-enum-base): New. > > gcc/cp/ChangeLog: > > * parser.cc (cp_parser_enum_specifier): Don't reject > elaborated-type-specifier with enum-base, instead emit new > Welaborated-enum-base warning. > > gcc/testsuite/ChangeLog: > > * g++.dg/cpp0x/enum40.C: Adjust expected diagnostics. > * g++.dg/cpp0x/forw_enum6.C: Likewise. > * g++.dg/cpp0x/elab-enum-base.C: New test. > <patch.txt>
