On Fri, 18 Aug 2023, Richard Sandiford via Gcc-patches wrote: > [[]] attributes are a recent addition to C, but as a GNU extension, > GCC allows them to be used in C11 and earlier. Normally this use > would trigger a pedwarn (for -pedantic, -Wc11-c2x-compat, etc.). > > This patch allows the pedwarn to be suppressed by starting the > attribute-list with __extension__. > > Also, :: is not a single lexing token prior to C2X, so it wasn't > possible to use scoped attributes in C11, even as a GNU extension. > The patch allows two colons to be used in place of :: when > __extension__ is used. No attempt is made to check whether the > two colons are immediately adjacent. > > gcc/ > * doc/extend.texi: Document the C [[__extension__ ...]] construct. > > gcc/c/ > * c-parser.cc (c_parser_std_attribute): Conditionally allow > two colons to be used in place of ::. > (c_parser_std_attribute_list): New function, split out from... > (c_parser_std_attribute_specifier): ...here. Allow the attribute-list > to start with __extension__. When it does, also allow two colons > to be used in place of ::. > > gcc/testsuite/ > * gcc.dg/c2x-attr-syntax-6.c: New test. > * gcc.dg/c2x-attr-syntax-7.c: Likewise.
OK. -- Joseph S. Myers jos...@codesourcery.com
