https://gcc.gnu.org/bugzilla/show_bug.cgi?id=108690
Bug ID: 108690
Summary: -Wstrict-prototypes too picky for C23
Product: gcc
Version: unknown
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: c
Assignee: unassigned at gcc dot gnu.org
Reporter: eggert at gnu dot org
Target Milestone: ---
We ran into this problem in Gnulib when considering how to migrate towards C23.
With GCC 12.2.1 20221121 (Red Hat 12.2.1-4) on x86-64, compile the following
one-line program t.c with 'gcc -S -std=gnu2x -Wstrict-prototypes t.c':
int f ();
GCC complains:
t.c:1:1: warning: function declaration isn’t a prototype [-Wstrict-prototypes]
1 | int f ();
| ^~~
This diagnostic is incorrect, because in C23 every function declaration and
definition is prototyped: 'int f ();' means the same thing as 'int f (void);'.
This incorrect warning is causing us to think we should stop using
-Wstrict-prototypes, but that would have a negative consequence in the common
case of pre-C23 builds.
In short, -Wstrict-prototypes should be a no-op in C23, since all functions are
prototyped in C23.
