Re: [PATCH] Accept pmf-vbit-in-delta extra warning

[Jason Merrill <jason@redhat.com>]

On 2/17/23 23:02, Alexandre Oliva wrote:
> 
> cp_build_binary_op, that issues -Waddress warnings, issues an extra
> warning on arm targets, that g++.dg/warn/Waddress-5.C does not expect
> when comparing a pointer-to-member-function literal with null.
> 
> The reason for the extra warning is that, on arm targets,
> TARGET_PTRMEMFUNC_VBIT_LOCATION == ptrmemfunc_vbit_in_delta, which
> causes a different path to be taken, that extracts the
> pointer-to-function and the delta fields (minus the vbit) and compares
> each one with zero.  It's when comparing this pointer-to-function with
> zero, in a recursive cp_build_binary_op, that another warning is
> issued.
> 
> I suppose there should be a way to skip the warning in this recursive
> call, without disabling other warnings that might be issued there, but

warning_sentinel ws (warn_address)

?

> this patch only arranges for the test to tolerate the extra warning.
> 
> Regstrapped on x86_64-linux-gnu.
> Tested on arm-vxworks7 (gcc-12) and arm-eabi (trunk).  Ok to install?

OK

> for  gcc/testsuite/ChangeLog
> 
> 	* g++.dg/warn/Waddress-5.C: Tolerate extra -Waddress warning.
> ---
>   gcc/testsuite/g++.dg/warn/Waddress-5.C |    6 +++++-
>   1 file changed, 5 insertions(+), 1 deletion(-)
> 
> diff --git a/gcc/testsuite/g++.dg/warn/Waddress-5.C b/gcc/testsuite/g++.dg/warn/Waddress-5.C
> index b1287b2fac316..1de88076f7767 100644
> --- a/gcc/testsuite/g++.dg/warn/Waddress-5.C
> +++ b/gcc/testsuite/g++.dg/warn/Waddress-5.C
> @@ -23,7 +23,11 @@ void T (bool);
>   void warn_memptr_if ()
>   {
>     // Exercise warnings for addresses of nonstatic member functions.
> -  if (&A::f == 0)         // { dg-warning "the address '&A::f'" }
> +  // On targets with TARGET_PTRMEMFUNC_VBIT_LOCATION ==
> +  // ptrmemfunc_vbit_in_delta, cp_build_binary_op recurses to compare
> +  // the pfn from the ptrmemfunc with null, so we get two warnings.
> +  // This matches both.  ??? Should we disable one of them?
> +  if (&A::f == 0)         // { dg-warning "A::f" }
>       T (0);
>   
>     if (&A::vf)             // { dg-warning "-Waddress" }
>