re PR c++/79687 (Wrong code with pointer-to-member)

	PR c++/79687
	* init.c (constant_value_1): Break if the variable has a dynamic
	initializer.

	* g++.dg/expr/ptrmem8.C: New test.
	* g++.dg/expr/ptrmem9.C: New test.

From-SVN: r246008

gcc/cp/ChangeLog

@@ -4,6 +4,10 @@
 	* tree.c (strip_typedefs): Skip the attribute handling if T is
 	a variant type which hasn't been updated yet.
 
+	PR c++/79687 - wrong code with pointer-to-member
+	* init.c (constant_value_1): Break if the variable has a dynamic
+	initializer.
+
 2017-03-08  Jason Merrill  <jason@redhat.com>
 
 	PR c++/79797 - ICE with self-reference in array DMI.

gcc/cp/init.c

@@ -2203,6 +2203,13 @@ constant_value_1 (tree decl, bool strict_p, bool return_aggregate_cst_ok_p)
       if (TREE_CODE (init) == CONSTRUCTOR
 	  && !DECL_INITIALIZED_BY_CONSTANT_EXPRESSION_P (decl))
 	break;
+      /* If the variable has a dynamic initializer, don't use its
+	 DECL_INITIAL which doesn't reflect the real value.  */
+      if (VAR_P (decl)
+	  && TREE_STATIC (decl)
+	  && !DECL_INITIALIZED_BY_CONSTANT_EXPRESSION_P (decl)
+	  && DECL_NONTRIVIALLY_INITIALIZED_P (decl))
+	break;
       decl = unshare_expr (init);
     }
   return decl;

gcc/testsuite/ChangeLog

+2017-03-09  Marek Polacek  <polacek@redhat.com>
+
+	PR c++/79687
+	* g++.dg/expr/ptrmem8.C: New test.
+	* g++.dg/expr/ptrmem9.C: New test.
+
 2017-03-09  Richard Biener  <rguenther@suse.de>
 
 	PR tree-optimization/79977

gcc/testsuite/g++.dg/expr/ptrmem8.C

+// PR c++/79687
+// { dg-do run }
+
+struct A
+{
+  char c;
+};
+
+int main()
+{
+  char A::* p = &A::c;
+  static char A::* const q = p;
+  A a;
+  return &(a.*q) - &a.c;
+}

gcc/testsuite/g++.dg/expr/ptrmem9.C

+// PR c++/79687
+// { dg-do run }
+
+struct A
+{
+  char c;
+};
+
+int main()
+{
+  static char A::* p1 = &A::c;
+  char A::* const q1 = p1;
+
+  char A::* p2 = &A::c;
+  static char A::* const q2 = p2;
+
+  A a;
+  return (&(a.*q1) - &a.c) || (&(a.*q2) - &a.c);
+}