> On 6 Oct 2022, at 22:44, Jason Merrill <ja...@redhat.com> wrote:
>
> On 10/3/22 23:53, Jason Merrill wrote:
>> On 9/30/22 18:50, Iain Sandoe wrote:
>>> Hi Jason,
>>>
>>>> On 30 Sep 2022, at 23:06, Jason Merrill <ja...@redhat.com> wrote:
>>>>
>>>> You can't use CONVERT_EXPR to convert between two class types, and it was
>>>> breaking copy elision.
>>>>
>>>> Unfortunately, this patch breaks symmetric-transfer-00-basic.C, where
>>>> susp_type is Loopy<int>::handle_type. How is this supposed to work?
>>>
>>> We are trying to save a type-erased handle (which the symmetric transfer
>>> makes
>>> and indirect call through, nothing else).
>> The problem is you're treating one class directly as another class here,
>> without the indirection involved in usual type-erasure idioms.
>> It does seem that the gimplifier handles this fine, but it doesn't
>> correspond to anything in the language and much of the front end assumes
>> that CONVERT_EXPR is only used for scalars. VIEW_CONVERT_EXPR would better
>> express that we're not doing anything to the value, just cheating the type
>> system. That's still dodgy from a language perspective, but probably safe
>> enough in this case.
>
> So I'm applying this:<0001-c-fix-broken-conversion-in-coroutines.patch>
thanks, I have not had any cycles to look at this.
however, when I next do - was planning on looking at the:
cont = handle.from_address(await_suspend().address())
approach, since both .address() and .from_address() are constexpr,
cp_fold_function should turn that into essentially a NOP.
Iain
