[clang] [Clang] Fix a concept subsumption bug when template depths are adjusted (PR #186735)

[Shafik Yaghmour via cfe-commits]

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@@ -2575,7 +2544,15 @@ bool Sema::IsAtLeastAsConstrained(const NamedDecl *D1,
   }
 
   SubsumptionChecker SC(*this);
-  std::optional<bool> Subsumes = SC.Subsumes(D1, AC1, D2, AC2);
+  // Associated declarations are used as a cache key in the event they were
+  // normalized earlier during concept checking. However we cannot reuse these
+  // cached results if any of the template depths have been adjusted.
+  const NamedDecl *DeclAC1 = D1, *DeclAC2 = D2;
+  if (Depth2 > Depth1)
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shafik wrote:

I have to say the naming here is really not great, I don't have suggestions but the names don't help me understand the code at all.

https://github.com/llvm/llvm-project/pull/186735