* constexpr.c (potential_constant_expression_1): Allow 'this' capture.

From-SVN: r249077

gcc/cp/ChangeLog

+2017-06-09  Jason Merrill  <jason@redhat.com>
+
+	* constexpr.c (potential_constant_expression_1): Allow 'this' capture.
+
 2017-06-09  Jan Hubicka  <hubicka@ucw.cz>
 
 	* class.c (build_vtbl_initializer): Mark dvirt_fn as cold.

gcc/cp/constexpr.c

@@ -5296,7 +5296,7 @@ potential_constant_expression_1 (tree t, bool want_rval, bool strict,
       {
         tree x = TREE_OPERAND (t, 0);
         STRIP_NOPS (x);
-        if (is_this_parameter (x))
+        if (is_this_parameter (x) && !is_capture_proxy (x))
 	  {
 	    if (DECL_CONTEXT (x)
 		&& !DECL_DECLARED_CONSTEXPR_P (DECL_CONTEXT (x)))

gcc/testsuite/g++.dg/cpp1z/lambda-this3.C

+// { dg-options -std=c++1z }
+
+struct S {
+  int i;
+  constexpr S() : i(5) { 
+    ([*this] () { return i + 10; }());
+  }
+  constexpr operator int() const { return i; }
+};
+constexpr int x = S();