re PR c++/54777 ([C++11] Comma operator in constexpr environment can cause ICE)

	PR c++/54777
	* semantics.c (cxx_eval_constant_expression) <case COMPOUND_EXPR>: If
	not ignoring the second operand, pass the original second operand
	and not one with stripped nops to cxx_eval_constant_expression.

	* g++.dg/cpp0x/constexpr-ref4.C: New test.

From-SVN: r192036

gcc/cp/ChangeLog

+2012-10-03  Jakub Jelinek  <jakub@redhat.com>
+
+	PR c++/54777
+	* semantics.c (cxx_eval_constant_expression) <case COMPOUND_EXPR>: If
+	not ignoring the second operand, pass the original second operand
+	and not one with stripped nops to cxx_eval_constant_expression.
+
 2012-10-01  Jason Merrill  <jason@redhat.com>
 
 	* decl.c (check_initializer): Set DECL_NONTRIVIALLY_INITIALIZED_P

gcc/cp/semantics.c

@@ -7740,6 +7740,7 @@ cxx_eval_constant_expression (const constexpr_call *call, tree t,
 	    /* Check that the LHS is constant and then discard it.  */
 	    cxx_eval_constant_expression (call, op0, allow_non_constant,
 					  false, non_constant_p);
+	    op1 = TREE_OPERAND (t, 1);
 	    r = cxx_eval_constant_expression (call, op1, allow_non_constant,
 					      addr, non_constant_p);
 	  }

gcc/testsuite/ChangeLog

+2012-10-03  Jakub Jelinek  <jakub@redhat.com>
+
+	PR c++/54777
+	* g++.dg/cpp0x/constexpr-ref4.C: New test.
+
 2012-10-02  Janus Weil  <janus@gcc.gnu.org>
 
 	PR fortran/54778

gcc/testsuite/g++.dg/cpp0x/constexpr-ref4.C

+// PR c++/54777
+// { dg-options -std=c++0x }
+
+struct S
+{
+  int s[1];
+  constexpr const int &foo (unsigned i) { return (i < 1 ? 0 : throw 1), s[i]; }
+  constexpr const int &bar (unsigned i) { return i < 1 ? s[i] : (throw 0, s[i]); }
+};
+
+int
+main ()
+{
+  constexpr S a {};
+  constexpr int i = a.foo (0);
+  constexpr int j = a.bar (0);
+  static_assert (i == j, "Ouch");
+}