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

[Jakub Jelinek <jakub@redhat.com>]

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.

	* 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