On 1/20/22 10:03, Jakub Jelinek wrote:
On Thu, Jan 20, 2022 at 09:56:59AM -0700, Martin Sebor wrote:
With normal -Wformat I see all expected warnings in:
char *foo (const char *) __attribute__((format_arg(1)));
void bar (const char *, ...) __attribute__((format(printf, 1, 2)));
-Wformat-diag is internal to GCC and needs one of the GCC-internal
attributes to enable, like __gcc_cxxdiag__, for example like this:
__attribute__ ((format (__gcc_cxxdiag__, 1, 2)))
void bar (const char *, ...);
With that it triggers in all the same instances as -Wformat below
(as near I can tell for a modified test case).
Glad to hear that, but then I don't understand why we didn't warn on
cp/error.cc before Martin L.'s change when --disable-nls wasn't used.
Good question! There does seem to be some strange interplay between
parentheses and -Wformat for __gcc_cdiag__ functions in the C++ front
end:
__attribute__ ((format (__gcc_cxxdiag__, 1, 2)))
void bar (const char *, ...);
void
baz (int x)
{
bar (x ? "<%s" : "%i", x); // -Wformat-diag
bar ((x ? "<%s" : "%i"), x); // silence
bar ((x ? ("<%s") : ("%i")), x); // silence
}
The C front end warns on all three calls.
With attribute printf both the C and C++ front ends issue a -Wformat
for all three calls as expected (passing an int to %s).
Martin
