[clang] [C++26][clang] Implement P2795R5 'Erroneous behaviour for uninitialized reads' (PR #177614)

[Erich Keane via cfe-commits]

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@@ -982,6 +982,7 @@ def Uninitialized  : DiagGroup<"uninitialized", [UninitializedSometimes,
                                                  UninitializedStaticSelfInit,
                                                  UninitializedConstReference,
                                                  UninitializedConstPointer]>;
+def ErroneousBehavior : DiagGroup<"erroneous-behavior">;
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erichkeane wrote:

SHOULD we add this to a group?  It would make sense at least to put this in Wall.

https://github.com/llvm/llvm-project/pull/177614