[libcxx-commits] [PATCH] D135292: [libc++][format] Improves CTAD.

[Mark de Wever via Phabricator via libcxx-commits]

Mordante marked an inline comment as done.
Mordante added inline comments.


================
Comment at: libcxx/include/__config:1206-1208
+#    define _LIBCPP_CTAD_SUPPORTED_FOR_TYPE(_ClassName)                                                                \
+      template <class _Tag = void>                                                                                     \
+      _ClassName(typename _Tag::__allow_ctad)->_ClassName<_Tag>
----------------
ldionne wrote:
> ldionne wrote:
> > Can we instead try this?
> > 
> > ```
> > #define _LIBCPP_CTAD_SUPPORTED_FOR_TYPE(_ClassName) \
> >   template <class ..._Tag> \
> >   _ClassName(typename _Tag::__allow_ctad...) -> _ClassName<_Tag...>;
> > ```
> > 
> > Would that allow handling class templates that take any number of arguments?
> In a follow-up patch, I think we could consider also renaming this macro to `_LIBCPP_CTAD_INTENDED_TO_WORK`? We can bikeshed on that but I think we can find something better than `_LIBCPP_CTAD_SUPPORTED_FOR_TYPE`.
I tried this locally and it works, let's see what the CI thinks.


Repository:
  rG LLVM Github Monorepo

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  https://reviews.llvm.org/D135292/new/

https://reviews.llvm.org/D135292