Re: [PATCH] cpp/c: Add -Wexpansion-to-defined

["Manuel López-Ibáñez" <lopezibanez@gmail.com>]

On 09/08/16 16:59, Paolo Bonzini wrote:
> Index: gcc/c-family/c-opts.c
> ===================================================================
> --- gcc/c-family/c-opts.c	(revision 239276)
> +++ gcc/c-family/c-opts.c	(working copy)
> @@ -1256,6 +1256,10 @@ sanitize_cpp_opts (void)
>    cpp_opts->unsigned_char = !flag_signed_char;
>    cpp_opts->stdc_0_in_system_headers = STDC_0_IN_SYSTEM_HEADERS;
>
> +  cpp_opts->warn_expansion_to_defined = cpp_warn_expansion_to_defined;
> +  if (cpp_warn_expansion_to_defined == -1)
> +    cpp_warn_expansion_to_defined = pedantic || extra_warnings;
> +

Instead of the above, plase use LangEnabledBy() or EnabledBy() in c.opt. See 
Wendif-labels and other examples. Then, you do not need Init(-1).

>    /* Wlong-long is disabled by default. It is enabled by:
>        [-Wpedantic | -Wtraditional] -std=[gnu|c]++98 ; or
>        [-Wpedantic | -Wtraditional] -std=non-c99
> Index: gcc/c-family/c.opt
> ===================================================================
> --- gcc/c-family/c.opt	(revision 239276)
> +++ gcc/c-family/c.opt	(working copy)
> @@ -506,6 +506,10 @@ Wdouble-promotion
>  C ObjC C++ ObjC++ Var(warn_double_promotion) Warning
>  Warn about implicit conversions from \"float\" to \"double\".
>
> +Wexpansion-to-defined
> +C ObjC C++ ObjC++ CppReason(CPP_W_EXPANSION_TO_DEFINED) Var(cpp_warn_expansion_to_defined) Init(-1) Warning
> +Warn if an undefined macro is used in an #if directive.
> +

You are also missing CPP(warn_expansion_to_defined) so that the cpp and gcc 
sides are in sync even when using pragmas.

Cheers,

	Manuel.