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Re: [PATCH 2/2] Support string locations for C++ in -Wformat (PR c++/56856)
On Thu, Oct 4, 2018 at 10:12 AM David Malcolm <dmalcolm@redhat.com> wrote:
>
> -Wformat in the C++ FE doesn't work as well as it could:
> (a) it doesn't report precise locations within the string literal, and
> (b) it doesn't underline arguments for those arguments !CAN_HAVE_LOCATION_P,
> despite having location wrapper nodes.
>
> For example:
>
> Wformat-ranges.C:32:10: warning: format '%s' expects argument of type 'char*', but argument 2 has type 'int' [-Wformat=]
> 32 | printf("hello %s", 42);
> | ^~~~~~~~~~
>
> (a) is due to not wiring up the langhook for extracting substring
> locations.
>
> This patch uses the one in c-family; it also fixes string literal
> parsing so that it records string concatenations (needed for
> extracting substring locations from concatenated strings).
>
> (b) is due to the call to maybe_constant_value here:
> fargs[j] = maybe_constant_value (argarray[j]);
> within build_over_call.
Maybe we should remove that in favor of fold_for_warn in
check_function_arguments.
Jason