https://gcc.gnu.org/bugzilla/show_bug.cgi?id=69585
--- Comment #4 from CVS Commits <cvs-commit at gcc dot gnu.org> --- The trunk branch has been updated by Marek Polacek <mpola...@gcc.gnu.org>: https://gcc.gnu.org/g:aec868578d8515763d75693c1fdfbc30ff0a1e68 commit r13-991-gaec868578d8515763d75693c1fdfbc30ff0a1e68 Author: Marek Polacek <pola...@redhat.com> Date: Thu Jun 2 15:44:20 2022 -0400 c++: Allow mixing GNU/std-style attributes [PR69585] cp_parser_attributes_opt doesn't accept GNU attributes followed by [[]] attributes and vice versa; only a sequence of attributes of the same kind. That causes grief for code like: struct __attribute__ ((may_alias)) alignas (2) struct S { }; or #define EXPORT __attribute__((visibility("default"))) struct [[nodiscard]] EXPORT F { }; It doesn't seem to a documented restriction, so this patch fixes the problem. However, the patch does not touch the C FE. The C FE doesn't have a counterpart to C++'s cp_parser_attributes_opt -- it only has c_parser_transaction_attributes (which parses both GNU and [[]] attributes), but that's TM-specific. The C FE seems to use either c_parser_gnu_attributes or c_parser_std_attribute_specifier_sequence. As a consequence, this works: [[maybe_unused]] __attribute__((deprecated)) void f2 (); but this doesn't: __attribute__((deprecated)) [[maybe_unused]] void f1 (); I'm not sure what, if anything, should be done about this. PR c++/102399 PR c++/69585 gcc/cp/ChangeLog: * parser.cc (cp_parser_attributes_opt): Accept GNU attributes followed by [[]] attributes and vice versa. gcc/testsuite/ChangeLog: * g++.dg/ext/attrib65.C: New test. * g++.dg/ext/attrib66.C: New test. * g++.dg/ext/attrib67.C: New test.
