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Re: [PATCH 1/4] Support lambda templates.


On 03.09.2013 22:25, Jason Merrill wrote:
On 09/03/2013 03:50 PM, Adam Butcher wrote:
Problem is that no RTL is set for the incoming parms in the
instantiation of the expansion. It ICEs in gimple_expand_cfg because 'DECL_RTL_IF_SET (var)' returns nullptr for the incoming parms resulting in a failed assertion that
SA.partition_to_pseudo[i] is non-null.

Sounds like a problem with how _FUN's parameters are instantiated.
I'm not sure why it would be special.

Does using a function parameter pack in the lambda body work
currently?  If so, how are the expanded parameters different?

Yes it does work. And I think (hope) I've cracked it; make_pack_expansion needs to be called in the body of the thunk (i.e. after start_preparsed_function).

If I butcher the implementation so that I rewrite any parameter packs with their expansion prior to building the call in return statement, it seems to work.

Certainly the following does what I expect it to, the trees look right and, more importantly, it doesn't ICE!

   auto g = [] <typename... P> (P...) -> float { return 3.f; };

   float (*pg3) (double, double, double) = g;

   return pg3(1,2,3);

I'll try to clean up what I've got then submit a rolled up patch.

Cheers,
Adam


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