Re: [PATCH] Fix PR c++/70332 (ICE due to aggregate initialization of NSDMI)

[Jason Merrill <jason@redhat.com>]

On 03/22/2016 07:12 PM, Patrick Palka wrote:
> On Tue, Mar 22, 2016 at 6:12 PM, Patrick Palka <patrick@parcs.ath.cx> wrote:
>> On Tue, Mar 22, 2016 at 6:00 PM, Jason Merrill <jason@redhat.com> wrote:
>>> On 03/22/2016 05:35 PM, Patrick Palka wrote:
>>>>
>>>> +             if (cp_unevaluated_operand == 0
>>>
>>>
>>> Why check this here?
>>
>> Just so that the change doesn't affect the behavior of tsubst_decl()
>> when cp_unevaluated_operand != 0.  Presumably the existing code (10
>> lines below) handles that case just fine.
>
> Turns out that without the check we can trigger the cxx_dialect >=
> cxx14 assert because in c++11 mode we can reach the assert through
> get_defaulted_eh_spec() which increments cp_unevaluated_operand and
> then calls get_nsdmi (..., /*in_ctor=*/false) causing
> current_class_ref to get set to a PLACEHOLDER_EXPR.
>
> So for example g++.dg/cpp0x/nsdmi-template2.C regresses with an ICE.
> So it seems the cp_unevaluated_operand != 0 check is necessary as long
> as the assert stays.
>
> There are no regressions if both the cp_unevaluated_operand check and
> the assert are removed however.

I think that's my preference.

Jason