[clang] [Clang] Diagnose forming references to nullptr (PR #143667)

[Corentin Jabot via cfe-commits]

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@@ -1540,6 +1540,7 @@ static bool isModification(AccessKinds AK) {
   case AK_DynamicCast:
   case AK_TypeId:
   case AK_IsWithinLifetime:
+  case AK_ReferenceInitialization:
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cor3ntin wrote:

well, `AK_ReferenceInitialization` mostly _checks_ the initialization is valid, it doesn't modify any object 

https://github.com/llvm/llvm-project/pull/143667