Hi!
On the following testcase, build_conditional_expr_1 tries hard to make sure
that if both arguments are xvalue_p (or one is and the other throw) the
result is still xvalue_p. But, later on we call unary_complex_lvalue,
which does rationalize_conditional_expr which changes it from
cond ? x : y to *(cond ? &x : &y) and that change turns something formerly
xvalue_p into newly lvalue_p.
Fixed thusly, bootstrapped/regtested on x86_64-linux and i686-linux,
ok for trunk?
2018-11-29 Jakub Jelinek <ja...@redhat.com>
PR c++/88103
* typeck.c (unary_complex_lvalue): If a COND_EXPR is xvalue_p, make
sure the result is as well.
* g++.dg/cpp0x/rv-cond3.C: New test.
--- gcc/cp/typeck.c.jj 2018-11-27 09:48:58.506103668 +0100
+++ gcc/cp/typeck.c 2018-11-29 21:00:33.900636750 +0100
@@ -6503,7 +6503,16 @@ unary_complex_lvalue (enum tree_code cod
/* Handle (a ? b : c) used as an "lvalue". */
if (TREE_CODE (arg) == COND_EXPR
|| TREE_CODE (arg) == MIN_EXPR || TREE_CODE (arg) == MAX_EXPR)
- return rationalize_conditional_expr (code, arg, tf_warning_or_error);
+ {
+ tree ret = rationalize_conditional_expr (code, arg, tf_warning_or_error);
+ /* Preserve xvalue kind. */
+ if (xvalue_p (arg))
+ {
+ tree reftype = cp_build_reference_type (TREE_TYPE (arg), true);
+ ret = cp_convert (reftype, ret, tf_warning_or_error);
+ }
+ return ret;
+ }
/* Handle (a = b), (++a), and (--a) used as an "lvalue". */
if (TREE_CODE (arg) == MODIFY_EXPR
--- gcc/testsuite/g++.dg/cpp0x/rv-cond3.C.jj 2018-11-29 21:04:48.228440774
+0100
+++ gcc/testsuite/g++.dg/cpp0x/rv-cond3.C 2018-11-29 21:06:22.315888491
+0100
@@ -0,0 +1,22 @@
+// PR c++/88103
+// { dg-do compile { target c++11 } }
+
+struct A {
+ A (int);
+ A&& foo () &&;
+ int i;
+};
+void free (A&&);
+
+void test_xvalue (A a){
+ A&& ref = true ? static_cast<A&&> (a) : static_cast<A&&> (a);
+ free (true ? static_cast<A&&> (a) : static_cast<A&&> (a));
+ (true ? static_cast<A&&> (a) : static_cast<A&&> (a)).foo ();
+ int&& k = (true ? static_cast<A&&> (a) : static_cast<A&&> (a)).i;
+}
+void test_prvalue (A a){
+ A&& ref = true ? static_cast<A&&> (a) : 1;
+ free (true ? static_cast<A&&> (a) : 1);
+ (true ? static_cast<A&&> (a) : 1).foo ();
+ int&& k = (true ? static_cast<A&&> (a) : 1).i;
+}
Jakub
