[clang] Initial implementation of P2719 (PR #113510)

[Erich Keane via cfe-commits]

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@@ -307,6 +307,10 @@ EXTENSION(datasizeof, LangOpts.CPlusPlus)
 
 FEATURE(cxx_abi_relative_vtable, LangOpts.CPlusPlus && LangOpts.RelativeCXXABIVTables)
 
+// Type aware allocators
+FEATURE(cxx_type_aware_allocators, LangOpts.TypeAwareAllocators)
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erichkeane wrote:

Reminds me: Do we need/have a feature test macro for these?

https://github.com/llvm/llvm-project/pull/113510