[gcc r13-6941] c++: Avoid informs without a warning [PR109278]

[Jakub Jelinek]

https://gcc.gnu.org/g:ee6ae8cb4793041590b479346433ed786a86985d

commit r13-6941-gee6ae8cb4793041590b479346433ed786a86985d
Author: Jakub Jelinek <jakub@redhat.com>
Date:   Thu Mar 30 09:34:12 2023 +0200

    c++: Avoid informs without a warning [PR109278]
    
    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.
    
    2023-03-30  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.

Diff:
---
 gcc/cp/call.cc                              | 20 ++++++++++++--------
 gcc/testsuite/g++.dg/cpp23/ext-floating15.C | 11 +++++++++++
 2 files changed, 23 insertions(+), 8 deletions(-)

diff --git a/gcc/cp/call.cc b/gcc/cp/call.cc
index 5df0f7ddee9..cdd7701b9e7 100644
--- a/gcc/cp/call.cc
+++ b/gcc/cp/call.cc
@@ -8296,7 +8296,7 @@ convert_like_internal (conversion *convs, tree expr, tree fn, int argnum,
 	  || 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, tree expr, tree fn, int argnum,
 							    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, tree expr, tree fn, int argnum,
 				  "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);
diff --git a/gcc/testsuite/g++.dg/cpp23/ext-floating15.C b/gcc/testsuite/g++.dg/cpp23/ext-floating15.C
new file mode 100644
index 00000000000..316dd5abacd
--- /dev/null
+++ b/gcc/testsuite/g++.dg/cpp23/ext-floating15.C
@@ -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);
+}