https://gcc.gnu.org/bugzilla/show_bug.cgi?id=117629
--- Comment #10 from GCC Commits <cvs-commit at gcc dot gnu.org> --- The master branch has been updated by David Malcolm <dmalc...@gcc.gnu.org>: https://gcc.gnu.org/g:321983033d621e3f75e11d380c4463956a3f6e1e commit r15-6507-g321983033d621e3f75e11d380c4463956a3f6e1e Author: David Malcolm <dmalc...@redhat.com> Date: Thu Jan 2 15:10:15 2025 -0500 c: special-case some "bool" errors with C23 (v2) [PR117629] Changed in v2: - distinguish between "bool" and "_Bool" when determining standard version This patch attempts to provide better error messages for code compiled with C23 that hasn't been updated for "bool", "true", and "false" becoming keywords. Specifically: (1) with "typedef int bool;" previously we emitted: t1.c:7:13: error: two or more data types in declaration specifiers 7 | typedef int bool; | ^~~~ t1.c:7:1: warning: useless type name in empty declaration 7 | typedef int bool; | ^~~~~~~ whereas with this patch we emit: t1.c:7:13: error: 'bool' cannot be defined via 'typedef' 7 | typedef int bool; | ^~~~ t1.c:7:13: note: 'bool' is a keyword with '-std=c23' onwards t1.c:7:1: warning: useless type name in empty declaration 7 | typedef int bool; | ^~~~~~~ (2) with "int bool;" previously we emitted: t2.c:7:5: error: two or more data types in declaration specifiers 7 | int bool; | ^~~~ t2.c:7:1: warning: useless type name in empty declaration 7 | int bool; | ^~~ whereas with this patch we emit: t2.c:7:5: error: 'bool' cannot be used here 7 | int bool; | ^~~~ t2.c:7:5: note: 'bool' is a keyword with '-std=c23' onwards t2.c:7:1: warning: useless type name in empty declaration 7 | int bool; | ^~~ (3) with "typedef enum { false = 0, true = 1 } _Bool;" previously we emitted: t3.c:7:16: error: expected identifier before 'false' 7 | typedef enum { false = 0, true = 1 } _Bool; | ^~~~~ t3.c:7:38: error: expected ';', identifier or '(' before '_Bool' 7 | typedef enum { false = 0, true = 1 } _Bool; | ^~~~~ t3.c:7:38: warning: useless type name in empty declaration whereas with this patch we emit: t3.c:7:16: error: cannot use keyword 'false' as enumeration constant 7 | typedef enum { false = 0, true = 1 } _Bool; | ^~~~~ t3.c:7:16: note: 'false' is a keyword with '-std=c23' onwards t3.c:7:38: error: expected ';', identifier or '(' before '_Bool' 7 | typedef enum { false = 0, true = 1 } _Bool; | ^~~~~ t3.c:7:38: warning: useless type name in empty declaration gcc/c/ChangeLog: PR c/117629 * c-decl.cc (declspecs_add_type): Special-case attempts to use bool as a typedef name or declaration name. * c-errors.cc (get_std_for_keyword): New. (add_note_about_new_keyword): New. * c-parser.cc (report_bad_enum_name): New, split out from... (c_parser_enum_specifier): ...here, adding handling for RID_FALSE and RID_TRUE. * c-tree.h (add_note_about_new_keyword): New decl. gcc/testsuite/ChangeLog: PR c/117629 * gcc.dg/auto-type-2.c: Update expected output with _Bool. * gcc.dg/c23-bool-errors-1.c: New test. * gcc.dg/c23-bool-errors-2.c: New test. * gcc.dg/c23-bool-errors-3.c: New test. Signed-off-by: David Malcolm <dmalc...@redhat.com>
