From: Jason Merrill <jason@redhat.com>
Date: Tue, 5 Apr 2022 20:02:04 +0000 (-0400)
Subject: c++: -Wshadow=compatible-local type vs var [PR100608]
X-Git-Tag: releases/gcc-11.3.0~64
X-Git-Url: http://git.ipfire.org/?a=commitdiff_plain;h=c52cd0b35d356565f67f7956f4defc022dfa2172;p=thirdparty%2Fgcc.git

c++: -Wshadow=compatible-local type vs var [PR100608]

The patch for PR92024 changed -Wshadow=compatible-local to warn if either
new or old decl was a type, but the rationale only talked about the case
where both are types.  If only one is, they aren't compatible.

	PR c++/100608

gcc/cp/ChangeLog:

	* name-lookup.c (check_local_shadow): Use -Wshadow=local
	if exactly one of 'old' and 'decl' is a type.

gcc/testsuite/ChangeLog:

	* g++.dg/warn/Wshadow-compatible-local-3.C: New test.
---

diff --git a/gcc/cp/name-lookup.c b/gcc/cp/name-lookup.c
index e9af670c28f4..2901e048b8d2 100644
--- a/gcc/cp/name-lookup.c
+++ b/gcc/cp/name-lookup.c
@@ -3259,6 +3259,10 @@ check_local_shadow (tree decl)
       enum opt_code warning_code;
       if (warn_shadow)
 	warning_code = OPT_Wshadow;
+      else if ((TREE_CODE (decl) == TYPE_DECL)
+	       ^ (TREE_CODE (old) == TYPE_DECL))
+	/* If exactly one is a type, they aren't compatible.  */
+	warning_code = OPT_Wshadow_local;
       else if ((TREE_TYPE (old)
 		&& TREE_TYPE (decl)
 		&& same_type_p (TREE_TYPE (old), TREE_TYPE (decl)))
diff --git a/gcc/testsuite/g++.dg/warn/Wshadow-compatible-local-3.C b/gcc/testsuite/g++.dg/warn/Wshadow-compatible-local-3.C
new file mode 100644
index 000000000000..0e5ece74b37b
--- /dev/null
+++ b/gcc/testsuite/g++.dg/warn/Wshadow-compatible-local-3.C
@@ -0,0 +1,10 @@
+// PR c++/100608
+// { dg-do compile { target c++11 } }
+// { dg-additional-options "-Wshadow=compatible-local" }
+
+template <typename> class X {};
+
+void foo()
+{
+  auto a = X<class a>{};	// no warning, not compatible
+}