Here, the problem was that in
(*(first + 1) < *first) != false
integral promotion changes the < expr to have type int. Then
fold_binary_op_with_conditional_arg wants to change this to
(*(first + 1) < *first) ? true : false
without changing the type, so the condition of a ?: has the wrong type
by the time we get to the constexpr expander. For 4.6, it seems
simplest to fix this by making the constexpr code more permissive.
Tested x86_64-pc-linux-gnu, applying to 4.6 and trunk.
commit 1be580e74a6e959ffaa041b49be08c895d44eb01
Author: Jason Merrill <ja...@redhat.com>
Date: Fri May 6 10:48:52 2011 -0400
PR c++/48909
* semantics.c (cxx_eval_conditional_expression): Check
integer_zerop/onep instead.
diff --git a/gcc/cp/semantics.c b/gcc/cp/semantics.c
index d0c559b..cc8db90 100644
--- a/gcc/cp/semantics.c
+++ b/gcc/cp/semantics.c
@@ -6299,13 +6299,12 @@ cxx_eval_conditional_expression (const constexpr_call
*call, tree t,
allow_non_constant, addr,
non_constant_p);
VERIFY_CONSTANT (val);
- if (val == boolean_true_node)
- return cxx_eval_constant_expression (call, TREE_OPERAND (t, 1),
+ /* Don't VERIFY_CONSTANT the other operands. */
+ if (integer_zerop (val))
+ return cxx_eval_constant_expression (call, TREE_OPERAND (t, 2),
allow_non_constant, addr,
non_constant_p);
- gcc_assert (val == boolean_false_node);
- /* Don't VERIFY_CONSTANT here. */
- return cxx_eval_constant_expression (call, TREE_OPERAND (t, 2),
+ return cxx_eval_constant_expression (call, TREE_OPERAND (t, 1),
allow_non_constant, addr,
non_constant_p);
}
@@ -7872,12 +7871,12 @@ potential_constant_expression_1 (tree t, bool
want_rval, tsubst_flags_t flags)
tmp = TREE_OPERAND (t, 0);
if (!potential_constant_expression_1 (tmp, rval, flags))
return false;
- else if (tmp == boolean_true_node)
- return potential_constant_expression_1 (TREE_OPERAND (t, 1),
- want_rval, flags);
- else if (tmp == boolean_false_node)
+ else if (integer_zerop (tmp))
return potential_constant_expression_1 (TREE_OPERAND (t, 2),
want_rval, flags);
+ else if (TREE_CODE (tmp) == INTEGER_CST)
+ return potential_constant_expression_1 (TREE_OPERAND (t, 1),
+ want_rval, flags);
for (i = 1; i < 3; ++i)
if (potential_constant_expression_1 (TREE_OPERAND (t, i),
want_rval, tf_none))
diff --git a/gcc/testsuite/g++.dg/cpp0x/constexpr-condition2.C
b/gcc/testsuite/g++.dg/cpp0x/constexpr-condition2.C
new file mode 100644
index 0000000..2434096
--- /dev/null
+++ b/gcc/testsuite/g++.dg/cpp0x/constexpr-condition2.C
@@ -0,0 +1,18 @@
+// PR c++/48909
+// { dg-options -std=c++0x }
+
+#define SA(X) static_assert((X),#X)
+
+constexpr int const * is_sorted_until(int const * first, int const * last)
+{
+ return first == last || first + 1 == last ? last
+ : (*(first + 1) < *first) != false ? first + 1
+ : is_sorted_until(first + 1, last);
+}
+
+int main()
+{
+ static constexpr int array[2] = {0, 1};
+ constexpr int const * last = is_sorted_until(array, array + 2);
+ SA(last==array+2);
+}
