On Tue, 2024-11-26 at 16:35 -0500, Marek Polacek wrote: > On Mon, Nov 25, 2024 at 10:49:02PM -0500, David Malcolm wrote: > > 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 (based on > > a brief review of the Gentoo bug tracker links given at > > https://gcc.gnu.org/pipermail/gcc/2024-November/245185.html). > > > > 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 > > > > > > Successfully bootstrapped & regrtested on x86_64-pc-linux-gnu. > > OK for trunk? > > Thanks for the patch. > > For: > > typedef int _Bool; > > or > > int _Bool; > > this patch says: > > note: '_Bool' is a keyword with '-std=c23' onwards > > but I don't think that's true: _Bool was added in C99 and is > obsolescent in > C23.
Is _Bool meant to be usable in c90? I tried with -std=c90 and it fails; see: https://godbolt.org/z/Wf6a9EKP9 <source>:1:13: error: two or more data types in declaration specifiers 1 | typedef int _Bool; | ^~~~~ <source>:1:1: warning: useless type name in empty declaration 1 | typedef int _Bool; | ^~~~~~~ Thanks Dave
