[clang] [Clang][C++26] Implement P3865R1 - CTAD for type template template parameters (PR #191409)

[Younan Zhang via cfe-commits]

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@@ -127,6 +127,8 @@ C++ Language Changes
 C++2c Feature Support
 ^^^^^^^^^^^^^^^^^^^^^
 
+- Implemented `P3865R1 <https://wg21.link/P3865R1>`_ CTAD for type template template parameters.
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zyn0217 wrote:

If this is implemented as a DR shouldn't we put it under DR supports section?

I'm not very familiar with the committee preferences here, just curious :)

https://github.com/llvm/llvm-project/pull/191409