re PR c++/61004 (Spurious warning: dereferencing type-punned pointer)

2014-06-05  Richard Biener  <rguenther@suse.de>

	PR c++/61004
	* typeck.c (cp_build_indirect_ref): Do not emit strict-aliasing
	warnings for accessing empty classes.

	* g++.dg/diagnostic/pr61004.C: New testcase.

From-SVN: r211272

gcc/cp/ChangeLog

+2014-06-05  Richard Biener  <rguenther@suse.de>
+
+	PR c++/61004
+	* typeck.c (cp_build_indirect_ref): Do not emit strict-aliasing
+	warnings for accessing empty classes.
+
 2014-06-05  Marek Polacek  <polacek@redhat.com>
 
 	PR c/49706

gcc/cp/typeck.c

@@ -2935,8 +2935,9 @@ cp_build_indirect_ref (tree ptr, ref_operator errorstring,
 	 of  the  result  is  "T."  */
       tree t = TREE_TYPE (type);
 
-      if (CONVERT_EXPR_P (ptr)
-          || TREE_CODE (ptr) == VIEW_CONVERT_EXPR)
+      if ((CONVERT_EXPR_P (ptr)
+	   || TREE_CODE (ptr) == VIEW_CONVERT_EXPR)
+	  && (!CLASS_TYPE_P (t) || !CLASSTYPE_EMPTY_P (t)))
 	{
 	  /* If a warning is issued, mark it to avoid duplicates from
 	     the backend.  This only needs to be done at

gcc/testsuite/ChangeLog

+2014-06-05  Richard Biener  <rguenther@suse.de>
+
+	PR c++/61004
+	* g++.dg/diagnostic/pr61004.C: New testcase.
+
 2014-06-05  Yuri Rumyantsev  <ysrumyan@gmail.com>
 
 	* gcc.dg/torture/pr61319.c: New test.

gcc/testsuite/g++.dg/diagnostic/pr61004.C

+// { dg-do compile }
+// { dg-options "-O2 -Wall" }
+
+struct A{ };
+struct B:A{};
+void f(A const&);
+int main()
+{
+  B b;
+  f(b); // { dg-bogus "strict-aliasing" }
+}