re PR c++/92695 (P1064R0 - virtual constexpr fails if object taken from array)

	PR c++/92695
	* constexpr.c (cxx_eval_constant_expression) <case OBJ_TYPE_REF>: Use
	STRIP_NOPS before checking for ADDR_EXPR.

	* g++.dg/cpp2a/constexpr-virtual15.C: New test.

From-SVN: r278912

gcc/cp/ChangeLog

+2019-12-02  Jakub Jelinek  <jakub@redhat.com>
+
+	PR c++/92695
+	* constexpr.c (cxx_eval_constant_expression) <case OBJ_TYPE_REF>: Use
+	STRIP_NOPS before checking for ADDR_EXPR.
+
 2019-11-29  Jakub Jelinek  <jakub@redhat.com>
 
 	PR c++/60228

gcc/cp/constexpr.c

@@ -5548,6 +5548,7 @@ cxx_eval_constant_expression (const constexpr_ctx *ctx, tree t,
 	tree obj = OBJ_TYPE_REF_OBJECT (t);
 	obj = cxx_eval_constant_expression (ctx, obj, lval, non_constant_p,
 					    overflow_p);
+	STRIP_NOPS (obj);
 	/* We expect something in the form of &x.D.2103.D.2094; get x. */
 	if (TREE_CODE (obj) != ADDR_EXPR
 	    || !DECL_P (get_base_address (TREE_OPERAND (obj, 0))))

gcc/testsuite/ChangeLog

+2019-12-02  Jakub Jelinek  <jakub@redhat.com>
+
+	PR c++/92695
+	* g++.dg/cpp2a/constexpr-virtual15.C: New test.
+
 2019-12-02  Richard Sandiford  <richard.sandiford@arm.com>
 
 	PR middle-end/92741

gcc/testsuite/g++.dg/cpp2a/constexpr-virtual15.C

+// PR c++/92695
+// { dg-do compile { target c++2a } }
+
+struct A { virtual int get() = 0; };
+struct B : A { constexpr int get() override { return 10; } };
+struct D { B b[2]; A* c{&(b[0])}; };
+static_assert(D{}.c->get() == 10);