Alexey Neyman <stilor@xxxxxxx> writes:
> Hi all,
>
> I've encountered a weird behavior of -Wmissing-field-initializers option
> (which is a part of -Wextra) regarding structure initializers that
> contain compound literals as initializers for some of their fields.
> Reproduced with all GCC versions from 4.8.5 to 11.2.
>
> Consider the following test case:
>
> struct foo {
> const char *a1;
> const char * const *a2;
> void *a3;
> void *a4;
> };
>
> const char *aux[] = { "y", 0 };
>
> struct foo a = {
> .a1 = "x",
> #if defined(CASE1)
> .a2 = (const char * const []){ "y", 0 },
> #elif defined(CASE2)
> .a2 = aux,
> #elif defined(CASE3)
> .a2 = 0,
> #elif defined(CASE4)
> /* .a2 not initialized */
> #elif defined(CASE5)
> .a2 = (const char * const []){ "y", 0 },
> .a3 = 0,
> #endif
> };
>
> struct foo b = {
> .a2 = (const char * const []){ "y", 0 },
> .a1 = "x",
> };
>
> CASE1 gives a warning about 'a3' field being initialized, despite the
> manual stating that named field initializers should prevent this warning
> from being generated. CASE2 initializes the field to point to an
> explicitly defined array, and it works with no warnings. CASE3 uses a
> constant as an initializer and also works without warnings. CASE5
> initializes the field 'a3' and produces no warnings about the next
> field, 'a4'.
>
> Reversing the order of the 'a1' and 'a2' initializers (as in the 'b'
> variable) also does not produce a warning. It seems that the warning is
> only produced if the last initialized field in a structure uses a
> compound literal.
>
> Looks like a bug to me; please confirm that I should file it into GCC's
> bugzilla.
Yeah, I agree it's a bug. I think it's likely to be the same underlying
issue as PR82283, so I've copied the example there (hope you don't mind).
Thanks,
Richard
