https://gcc.gnu.org/bugzilla/show_bug.cgi?id=99317
Martin Sebor <msebor at gcc dot gnu.org> changed:
What |Removed |Added
----------------------------------------------------------------------------
CC| |msebor at gcc dot gnu.org
Resolution|--- |WONTFIX
Status|UNCONFIRMED |RESOLVED
See Also| |https://gcc.gnu.org/bugzill
| |a/show_bug.cgi?id=44209
--- Comment #4 from Martin Sebor <msebor at gcc dot gnu.org> ---
To expand on Andrew's comment: The C rules specify the type of the result of
operator ?: when either of the second and third operands is a pointer to void,
but they do no specify the result type when the operands are pointers to
incompatible types (like int* and float*). The warning points out the latter.
The C++ rules, OTOH, are more restrictive and make the ?: expression valid only
when the types of the arguments can be implicitly converted to one another.
Since in C++ a pointer to void isn't implicitly convertible to a pointer to an
object type all the expressions in the test case are invalid.
In C mode, the -Wc++-compat option helps detect C/C++ incompatibilities and
detects this problem (below). So with that, since the problem is diagnosed
under the right option, I think this report can be resolved as WONTFIX. (That
the warning in comment #0 is issued unconditionally and not under the control
of a specific option, is a separate problem tracked in in bug 44209.)
$ gcc -S -Wall -Wc++-compat pr99317.c
pr99317.c: In function ‘foo’:
pr99317.c:3:17: warning: request for implicit conversion from ‘void *’ to
‘float *’ not permitted in C++ [-Wc++-compat]
3 | float * f = v;
| ^
pr99317.c:4:15: warning: request for implicit conversion from ‘void *’ to ‘int
*’ not permitted in C++ [-Wc++-compat]
4 | int * i = w;
| ^
pr99317.c:5:19: warning: pointer type mismatch in conditional expression
5 | return (x ? f : i);
| ^
pr99317.c:5:19: warning: request for implicit conversion from ‘void *’ to ‘int
*’ not permitted in C++ [-Wc++-compat]
5 | return (x ? f : i);
| ~~~~~~~^~~~
pr99317.c: In function ‘foo1’:
pr99317.c:10:17: warning: request for implicit conversion from ‘void *’ to
‘float *’ not permitted in C++ [-Wc++-compat]
10 | float * f = v;
| ^
pr99317.c:11:15: warning: request for implicit conversion from ‘void *’ to ‘int
*’ not permitted in C++ [-Wc++-compat]
11 | int * i = w;
| ^
pr99317.c:12:19: warning: request for implicit conversion from ‘void *’ to ‘int
*’ not permitted in C++ [-Wc++-compat]
12 | return (1 ? f : (void *)i);
| ~~~~~~~^~~~~~~~~~~~
pr99317.c: In function ‘bar’:
pr99317.c:16:17: warning: request for implicit conversion from ‘void *’ to
‘float *’ not permitted in C++ [-Wc++-compat]
16 | float * f = v;
| ^
pr99317.c:17:15: warning: request for implicit conversion from ‘void *’ to ‘int
*’ not permitted in C++ [-Wc++-compat]
17 | int * i = w;
| ^
pr99317.c:18:19: warning: request for implicit conversion from ‘void *’ to ‘int
*’ not permitted in C++ [-Wc++-compat]
18 | return (x ? f : (void *)i);
| ~~~~~~~^~~~~~~~~~~~
