[PATCH 39/59] elf: Suppress unused function clang warning for __ifunc_resolver

[Sam James]

Adhemerval Zanella <adhemerval.zanella@linaro.org> writes:

> The __ifunc_resolver macro expands to:
>
>    extern __typeof (__redirect_name) name __attribute__ ((ifunc ("iname_ifunc")));
>    static __typeof (__redirect_name) *name_ifunc (void) { [...] };
>
> And although NAME_IFUNC is and alias for NAME, clang still emits
> an 'unused function 'name_ifunc' [-Werror,-Wunused-function]'
> warning.  The static is used to avoid name pollution on static
> linkage.

A bug report for LLVM would be appreciated. See also
https://github.com/llvm/llvm-project/issues/63957 (lol).

Reviewed-by: Sam James <sam@gentoo.org>

> ---
>  include/libc-symbols.h | 6 +++++-
>  1 file changed, 5 insertions(+), 1 deletion(-)
>
> diff --git a/include/libc-symbols.h b/include/libc-symbols.h
> index b407fa8f7d..2f9453e0d7 100644
> --- a/include/libc-symbols.h
> +++ b/include/libc-symbols.h
> @@ -86,6 +86,7 @@
>  
>  /* Obtain the definition of symbol_version_reference.  */
>  #include <libc-symver.h>
> +#include <libc-diag.h>
>  
>  /* When PIC is defined and SHARED isn't defined, we are building PIE
>     by default.  */
> @@ -671,7 +672,10 @@ for linking")
>  # define __ifunc_args(type_name, name, expr, init, ...)			\
>    extern __typeof (type_name) name __attribute__			\
>  			      ((ifunc (#name "_ifunc")));		\
> -  __ifunc_resolver (type_name, name, expr, init, static, __VA_ARGS__)
> +  DIAG_PUSH_NEEDS_COMMENT_CLANG;					\
> +  DIAG_IGNORE_NEEDS_COMMENT_CLANG (13, "-Wunused-function");		\
> +  __ifunc_resolver (type_name, name, expr, init, static, __VA_ARGS__);	\
> +  DIAG_POP_NEEDS_COMMENT_CLANG;
>  
>  # define __ifunc_args_hidden(type_name, name, expr, init, ...)		\
>    __ifunc_args (type_name, name, expr, init, __VA_ARGS__)