re PR c++/53025 ([C++11] noexcept operator depends on copy-elision)

/cp
2014-10-02  Paolo Carlini  <paolo.carlini@oracle.com>

	PR c++/53025
	* cp-tree.h (struct saved_scope): Add noexcept_operand.
	(cp_noexcept_operand): Define.
	* call.c (build_over_call): Use it.
	* parser.c (cp_parser_unary_expression, [RID_NOEXCEPT]): Likewise.
	* pt.c (tsubst_copy_and_build, [NOEXCEPT_EXPR]): Likewise.

/testsuite
2014-10-02  Paolo Carlini  <paolo.carlini@oracle.com>

	PR c++/53025
	* g++.dg/cpp0x/noexcept23.C: New.
	* g++.dg/cpp0x/noexcept24.C: Likewise.

From-SVN: r215813

gcc/cp/ChangeLog

+2014-10-02  Paolo Carlini  <paolo.carlini@oracle.com>
+
+	PR c++/53025
+	* cp-tree.h (struct saved_scope): Add noexcept_operand.
+	(cp_noexcept_operand): Define.
+	* call.c (build_over_call): Use it.
+	* parser.c (cp_parser_unary_expression, [RID_NOEXCEPT]): Likewise.
+	* pt.c (tsubst_copy_and_build, [NOEXCEPT_EXPR]): Likewise.
+
 2014-10-01  Jason Merrill  <jason@redhat.com>
 
 	PR c++/63362

gcc/cp/call.c

@@ -7251,7 +7251,11 @@ build_over_call (struct z_candidate *cand, int flags, tsubst_flags_t complain)
     /* Do things the hard way.  */;
   else if (cand->num_convs == 1 
            && (DECL_COPY_CONSTRUCTOR_P (fn) 
-               || DECL_MOVE_CONSTRUCTOR_P (fn)))
+               || DECL_MOVE_CONSTRUCTOR_P (fn))
+	   /* It's unsafe to elide the constructor when handling
+	      a noexcept-expression, it may evaluate to the wrong
+	      value (c++/53025).  */
+	   && cp_noexcept_operand == 0)
     {
       tree targ;
       tree arg = argarray[num_artificial_parms_for (fn)];

gcc/cp/cp-tree.h

@@ -1058,6 +1058,7 @@ struct GTY(()) saved_scope {
 
   int unevaluated_operand;
   int inhibit_evaluation_warnings;
+  int noexcept_operand;
   /* If non-zero, implicit "omp declare target" attribute is added into the
      attribute lists.  */
   int omp_declare_target_attribute;
@@ -1124,6 +1125,10 @@ struct GTY(()) saved_scope {
 
 #define local_specializations scope_chain->x_local_specializations
 
+/* Nonzero if we are parsing the operand of a noexcept operator.  */
+
+#define cp_noexcept_operand scope_chain->noexcept_operand
+
 /* A list of private types mentioned, for deferred access checking.  */
 
 extern GTY(()) struct saved_scope *scope_chain;

gcc/cp/parser.c

@@ -7156,7 +7156,9 @@ cp_parser_unary_expression (cp_parser *parser, bool address_p, bool cast_p,
 
 	    ++cp_unevaluated_operand;
 	    ++c_inhibit_evaluation_warnings;
+	    ++cp_noexcept_operand;
 	    expr = cp_parser_expression (parser);
+	    --cp_noexcept_operand;
 	    --c_inhibit_evaluation_warnings;
 	    --cp_unevaluated_operand;
 

gcc/cp/pt.c

@@ -14769,11 +14769,13 @@ tsubst_copy_and_build (tree t,
       op1 = TREE_OPERAND (t, 0);
       ++cp_unevaluated_operand;
       ++c_inhibit_evaluation_warnings;
+      ++cp_noexcept_operand;
       op1 = tsubst_copy_and_build (op1, args, complain, in_decl,
 				   /*function_p=*/false,
 				   /*integral_constant_expression_p=*/false);
       --cp_unevaluated_operand;
       --c_inhibit_evaluation_warnings;
+      --cp_noexcept_operand;
       RETURN (finish_noexcept_expr (op1, complain));
 
     case MODOP_EXPR:

gcc/testsuite/ChangeLog

+2014-10-02  Paolo Carlini  <paolo.carlini@oracle.com>
+
+	PR c++/53025
+	* g++.dg/cpp0x/noexcept23.C: New.
+	* g++.dg/cpp0x/noexcept24.C: Likewise.
+
 2014-10-02  Marek Polacek  <polacek@redhat.com>
 
 	* gcc.dg/noncompile/20020130-1.c: Use -std=gnu89.

gcc/testsuite/g++.dg/cpp0x/noexcept23.C

+// PR c++/53025
+// { dg-do compile { target c++11 } }
+
+struct A {
+  A() noexcept {}
+  A(const A&) noexcept(false) {}
+};
+
+void a(A) noexcept {}
+
+void f()
+{
+  static_assert(!noexcept(a(A{})), "");
+}

gcc/testsuite/g++.dg/cpp0x/noexcept24.C

+// PR c++/53025
+// { dg-do compile { target c++11 } }
+
+template<typename T>
+struct A {
+  A() noexcept {}
+  A(const A&) noexcept(false) {}
+};
+
+template<typename T>
+void a(A<T>) noexcept {}
+
+template<typename T>
+void f()
+{
+  static_assert(!noexcept(a(A<T>{})), "");
+}
+
+void g()
+{
+  f<int>();
+}