[clang] [clang] Fix crash when compiling error with invalid decl (PR #77893)

[Erich Keane via cfe-commits]

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@@ -40,7 +40,11 @@ static_assert(
     "Type is insufficiently aligned");
 
 APValue::LValueBase::LValueBase(const ValueDecl *P, unsigned I, unsigned V)
-    : Ptr(P ? cast<ValueDecl>(P->getCanonicalDecl()) : nullptr), Local{I, V} {}
+    : Ptr(P ? cast<ValueDecl>(P->getCanonicalDecl()->isInvalidDecl()
+                                  ? P
+                                  : P->getCanonicalDecl())
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erichkeane wrote:

This part of the change doesn't really make sense to me either, it isn't clear why the invalid decl is assumed to have a not-invalid-canonical decl, thats an incorrect assumption.

https://github.com/llvm/llvm-project/pull/77893