From: Douglas Gregor (gregod_at_[hidden])
Date: 2002-03-21 13:00:56
On Wednesday 20 March 2002 12:44 pm, you wrote:
> I did some more thinking about that this morning, including reading the
> relevant part of the standard. It seems to me that we're still missing
> some very important predicates which we could get from a legality
> checker, like is_copyable<T>.
FWIW, I wrote a quick GCC hack a short while ago to add a compiler-supported
'can_instantiate' trait. 'can_instantiate<T>::value' is an ICE that will be
true if T can be instantiated (T is implicitly instantiated by the check) and
false otherwise (no errors will be emitted - compilation can continue on its
merry way). Along with the ability to format and emit warning and error
messages from a template metaprogram, the problems with nasty error messages
in template code can be solved more easily. I'll post more information once
I've got a good, nontrivial example.
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