[clang] [Clang] add support for C23 'H', 'D', and 'DD' length modifiers (PR #201098)

[Aaron Ballman via cfe-commits]

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@@ -236,6 +236,7 @@ C23 Feature Support
 ^^^^^^^^^^^^^^^^^^^
 - Clang now allows C23 ``constexpr`` struct member access through the dot operator in constant expressions. (#GH178349)
 - Clang now supports the C23 ``wN`` and ``wfN`` length modifiers. (#GH116962)
+- Clang now supports the C23 ``H``, ``D``, and ``DD`` length modifiers. (#GH116962)
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AaronBallman wrote:

We should clarify that we recognize them and diagnose their use because Clang doesn't currently support those types.

https://github.com/llvm/llvm-project/pull/201098