On Wed, Jan 31, 2018 at 11:21 AM, Jakub Jelinek <ja...@redhat.com> wrote:
> On Wed, Jan 31, 2018 at 11:05:17AM -0500, Jason Merrill wrote:
>> > 2018-01-24 Jakub Jelinek <ja...@redhat.com>
>> >
>> > PR c++/83993
>> > * constexpr.c (cxx_eval_outermost_constant_expr): Don't clear
>> > TREE_CONSTANT on ADDR_EXPRs.
>> >
>> > * g++.dg/init/pr83993-2.C: New test.
>> >
>> > --- gcc/cp/constexpr.c.jj 2018-01-24 13:38:40.572913190 +0100
>> > +++ gcc/cp/constexpr.c 2018-01-24 17:03:16.821440047 +0100
>> > @@ -4832,7 +4832,7 @@ cxx_eval_outermost_constant_expr (tree t
>> >
>> > if (non_constant_p && !allow_non_constant)
>> > return error_mark_node;
>> > - else if (non_constant_p && TREE_CONSTANT (r))
>> > + else if (non_constant_p && TREE_CONSTANT (r) && TREE_CODE (r) !=
>> > ADDR_EXPR)
>> > {
>> > /* This isn't actually constant, so unset TREE_CONSTANT. */
>> > if (EXPR_P (r))
>>
>> Hmm, what if we check for ADDR_EXPR in the EXPR_P test, so we build a
>> non-TREE_CONSTANT NOP_EXPR around the ADDR_EXPR instead?
>
> That looks like a good idea and works on the testcase in question,
> ok for trunk if it passes bootstrap/regtest?
>
> 2018-01-31 Jason Merrill <ja...@redhat.com>
> Jakub Jelinek <ja...@redhat.com>
>
> PR c++/83993
> * constexpr.c (cxx_eval_outermost_constant_expr): Build NOP_EXPR
> around non-constant ADDR_EXPRs rather than clearing TREE_CONSTANT
> on ADDR_EXPR.
>
> * g++.dg/init/pr83993-2.C: New test.
>
> --- gcc/cp/constexpr.c.jj 2018-01-30 12:30:24.279362188 +0100
> +++ gcc/cp/constexpr.c 2018-01-31 17:18:03.316302653 +0100
> @@ -4824,7 +4824,7 @@ cxx_eval_outermost_constant_expr (tree t
> else if (non_constant_p && TREE_CONSTANT (r))
> {
> /* This isn't actually constant, so unset TREE_CONSTANT. */
> - if (EXPR_P (r))
> + if (EXPR_P (r) && TREE_CODE (r) != ADDR_EXPR)
OK with an added comment about the middle end needing TREE_CONSTANT to
stay set on ADDR_EXPR.
Jason
