Re: [PATCH] c++: Avoid informs without a warning [PR109278]

[Jason Merrill <jason@redhat.com>]

On 3/25/23 06:08, Jakub Jelinek wrote:
> Hi!
> 
> On the following testcase we emit notes in
> maybe_inform_about_fndecl_for_bogus_argument_init
> despite no warning/error being printed before it.
> This is for the extended floating point type conversions where pedwarn
> is used, and complained is used there for 2 different purposes,
> one is whether an unspecific error should be emitted if we haven't
> complained otherwise, and one whether
> maybe_inform_about_fndecl_for_bogus_argument_init should be called.
> For the 2 pedwarns, currently it sets complained to true regardless of
> whether pedwarn succeeded, which results in the undesirable notes printed
> with -w.  If complained is initialized to result of pedwarn, we would
> emit an error later on.
> 
> So, the following patch makes complained a tristate, the additional
> error isn't printed if complained != 0, and
> maybe_inform_about_fndecl_for_bogus_argument_init is called only if
> complained == 1, so if pedwarn returns false, we can use complained = -1
> to tell later code not to emit an error and not to call
> maybe_inform_about_fndecl_for_bogus_argument_init.
> 
> Bootstrapped/regtested on x86_64-linux and i686-linux, ok for trunk?
> 
> 2023-03-25  Jakub Jelinek  <jakub@redhat.com>
> 
> 	PR c++/109278
> 	* call.cc (convert_like_internal): If pedwarn for extended float
> 	type conversions doesn't report anything, avoid calling
> 	maybe_inform_about_fndecl_for_bogus_argument_init.

I think we want the same handling for all the complained = permerror 
cases as well.

> 	* g++.dg/cpp23/ext-floating15.C: New test.
> 
> --- gcc/cp/call.cc.jj	2023-03-23 15:24:33.074801422 +0100
> +++ gcc/cp/call.cc	2023-03-24 22:29:06.328140170 +0100
> @@ -8296,7 +8296,7 @@ convert_like_internal (conversion *convs
>   	  || SCALAR_TYPE_P (totype))
>         && convs->kind != ck_base)
>       {
> -      bool complained = false;
> +      int complained = 0;
>         conversion *t = convs;
>   
>         /* Give a helpful error if this is bad because of excess braces.  */
> @@ -8328,14 +8328,18 @@ convert_like_internal (conversion *convs
>   							    totype))
>   	  {
>   	  case 2:
> -	    pedwarn (loc, 0, "converting to %qH from %qI with greater "
> -			     "conversion rank", totype, TREE_TYPE (expr));
> -	    complained = true;
> +	    if (pedwarn (loc, 0, "converting to %qH from %qI with greater "
> +				 "conversion rank", totype, TREE_TYPE (expr)))
> +	      complained = 1;
> +	    else if (!complained)
> +	      complained = -1;
>   	    break;
>   	  case 3:
> -	    pedwarn (loc, 0, "converting to %qH from %qI with unordered "
> -			     "conversion ranks", totype, TREE_TYPE (expr));
> -	    complained = true;
> +	    if (pedwarn (loc, 0, "converting to %qH from %qI with unordered "
> +				 "conversion ranks", totype, TREE_TYPE (expr)))
> +	      complained = 1;
> +	    else if (!complained)
> +	      complained = -1;
>   	    break;
>   	  default:
>   	    break;
> @@ -8389,7 +8393,7 @@ convert_like_internal (conversion *convs
>   				  "invalid conversion from %qH to %qI",
>   				  TREE_TYPE (expr), totype);
>   	}
> -      if (complained)
> +      if (complained == 1)
>   	maybe_inform_about_fndecl_for_bogus_argument_init (fn, argnum);
>   
>         return cp_convert (totype, expr, complain);
> --- gcc/testsuite/g++.dg/cpp23/ext-floating15.C.jj	2023-03-24 22:38:40.358890548 +0100
> +++ gcc/testsuite/g++.dg/cpp23/ext-floating15.C	2023-03-24 22:38:18.484204916 +0100
> @@ -0,0 +1,11 @@
> +// PR c++/109278
> +// { dg-do compile { target float128 } }
> +// { dg-options "-w" }
> +
> +void foo (long double);	// { dg-bogus "initializing argument 1 of" }
> +
> +void
> +bar (_Float128 x)
> +{
> +  foo (x);
> +}
> 
> 	Jakub
>