From: Martin Uecker <uecker@tugraz.at>
Date: Fri, 4 Aug 2023 05:48:21 +0000 (+0200)
Subject: c: _Generic should not warn in non-active branches [PR68193,PR97100,PR110703]
X-Git-Tag: basepoints/gcc-15~7135
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=54be338589ea93ad4ff53d22adde476a0582537b;p=thirdparty%2Fgcc.git

c: _Generic should not warn in non-active branches [PR68193,PR97100,PR110703]

To avoid false diagnostics, use c_inhibit_evaluation_warnings when
a generic association is known to not match during parsing.  We may
still generate false positives if the default branch comes earler than
a specific association that matches.

PR c/68193
PR c/97100
PR c/110703

gcc/c/:
	* c-parser.cc (c_parser_generic_selection): Inhibit evaluation
	warnings branches that are known not be taken during parsing.

gcc/testsuite/ChangeLog:
	* gcc.dg/pr68193.c: New test.
---

diff --git a/gcc/c/c-parser.cc b/gcc/c/c-parser.cc
index 7a9fdda6c88b..57a01dc2fa38 100644
--- a/gcc/c/c-parser.cc
+++ b/gcc/c/c-parser.cc
@@ -9392,7 +9392,17 @@ c_parser_generic_selection (c_parser *parser)
 	  return error_expr;
 	}
 
+      bool match = assoc.type == NULL_TREE
+		   || comptypes (assoc.type, selector_type);
+
+      if (!match)
+	c_inhibit_evaluation_warnings++;
+
       assoc.expression = c_parser_expr_no_commas (parser, NULL);
+
+      if (!match)
+	  c_inhibit_evaluation_warnings--;
+
       if (assoc.expression.value == error_mark_node)
 	{
 	  c_parser_skip_until_found (parser, CPP_CLOSE_PAREN, NULL);
@@ -9429,7 +9439,7 @@ c_parser_generic_selection (c_parser *parser)
 	      match_found = associations.length ();
 	    }
 	}
-      else if (comptypes (assoc.type, selector_type))
+      else if (match)
 	{
 	  if (match_found < 0 || matched_assoc.type == NULL_TREE)
 	    {
diff --git a/gcc/testsuite/gcc.dg/pr68193.c b/gcc/testsuite/gcc.dg/pr68193.c
new file mode 100644
index 000000000000..2267593e3633
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/pr68193.c
@@ -0,0 +1,15 @@
+/*  pr69193 */
+/* { dg-do compile } */
+/* { dg-options "-Wall" } */
+
+int
+main (void)
+{
+  int i = 0;
+  int j = _Generic (i,
+		    int: 0,
+		    long int: (i = (long int) 9223372036854775808UL));
+  return i + j;
+}
+
+