On Tuesday, 22 June 2021 21:52:16 CEST Jason Merrill wrote:
> For alias templates, you probably want the attribute only on the
> templated class, not on the instantiations.
Oh good point. My current patch does not allow the attribute on alias
templates. Consider:
template <class T, class U>
struct X {};
template <class T>
using foo [[gnu::diagnose_as]] = X<T, int>;
I have no idea how this could work. I would have to set the attribute for an
implicit partial specialization (not that I know of the existence of such a
thing)? I.e. X<int, int> would have to be diagnosed as foo<int>, but X<int,
float> would have to be diagnosed as X<int, float>, not foo.
So if anything it should only support alias templates if they are strictly
"renaming" the type. I.e. their template parameters must match up exactly. Can
I constrain the attribute like this? Or should we rely on developers to be
reasonable and only use it for template aliases with matching template params?
-Matthias
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Dr. Matthias Kretz https://mattkretz.github.io
GSI Helmholtz Centre for Heavy Ion Research https://gsi.de
std::experimental::simd https://github.com/VcDevel/std-simd
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