[clang] [Clang][C++23] Implement P2448R2: Relaxing some constexpr restrictions (PR #77753)

[Aaron Ballman via cfe-commits]

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@@ -2774,9 +2774,13 @@ def err_constexpr_tag : Error<
 def err_constexpr_dtor : Error<
   "destructor cannot be declared %sub{select_constexpr_spec_kind}0">;
 def err_constexpr_dtor_subobject : Error<
-  "destructor cannot be declared %sub{select_constexpr_spec_kind}0 because "
+  "destructor cannot be declared %sub{select_constexpr_spec_kind}0 before C++23 because "
   "%select{data member %2|base class %3}1 does not have a "
   "constexpr destructor">;
+def warn_cxx20_compat_constexpr_dtor_subobject : Warning<
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AaronBallman wrote:

We usually only issue the compat warnings in cases where we expose it as an extension in earlier modes, so I think this warning can go away.

https://github.com/llvm/llvm-project/pull/77753