On 1/13/21 12:05 PM, Patrick Palka wrote:
In the below testcase, the expression of the atomic constraint after substitution is (int *) NON_LVALUE_EXPR <1> != 0B which is not a C++ constant expression, but its TREE_CONSTANT flag is set (from build2), so satisfy_atom fails to notice that it's non-constant (and we end up tripping over the assert in satisfaction_value).Since TREE_CONSTANT doesn't necessarily correspond to C++ constantness, this patch makes satisfy_atom instead check is_rvalue_constant_expression. Bootstrapped and regtested on x86_64-pc-linux-gnu, does this look OK for trunk/10? gcc/cp/ChangeLog: PR c++/98644 * constraint.cc (satisfy_atom): Check is_rvalue_constant_expression instead of TREE_CONSTANT. gcc/testsuite/ChangeLog: PR c++/98644 * g++.dg/cpp2a/concepts-pr98644.C: New test. --- gcc/cp/constraint.cc | 2 +- gcc/testsuite/g++.dg/cpp2a/concepts-pr98644.C | 7 +++++++ 2 files changed, 8 insertions(+), 1 deletion(-) create mode 100644 gcc/testsuite/g++.dg/cpp2a/concepts-pr98644.C diff --git a/gcc/cp/constraint.cc b/gcc/cp/constraint.cc index 9049d087859..f99a25dc8a4 100644 --- a/gcc/cp/constraint.cc +++ b/gcc/cp/constraint.cc @@ -2969,7 +2969,7 @@ satisfy_atom (tree t, tree args, sat_info info) { result = maybe_constant_value (result, NULL_TREE, /*manifestly_const_eval=*/true); - if (!TREE_CONSTANT (result))
This should be sufficient. If the result isn't constant, maybe_constant_value shouldn't return it with TREE_CONSTANT set. See
/* This isn't actually constant, so unset TREE_CONSTANT.
in cxx_eval_outermost_constant_expr. Jason
