[clang] [clang][ExprConst] Fix crash on uninitialized array subobject (PR #67817)

[Shafik Yaghmour via cfe-commits]

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@@ -2411,10 +2411,15 @@ static bool CheckEvaluationResult(CheckEvaluationResultKind CERK,
                                   const FieldDecl *SubobjectDecl,
                                   CheckedTemporaries &CheckedTemps) {
   if (!Value.hasValue()) {
-    assert(SubobjectDecl && "SubobjectDecl shall be non-null");
-    Info.FFDiag(DiagLoc, diag::note_constexpr_uninitialized) << SubobjectDecl;
-    Info.Note(SubobjectDecl->getLocation(),
-              diag::note_constexpr_subobject_declared_here);
+    if (SubobjectDecl) {
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shafik wrote:

So if we look back at https://reviews.llvm.org/D146358 you used to get the location which could be invalid and the diagnostic that was based on that is now lost b/c we lost that information b/c in many cases you just pass `nullptr` explicitly. So Perhaps you should have been encoding that information as well and then understand why that is important here.

https://github.com/llvm/llvm-project/pull/67817