[clang] [clang] Consistently cache failed constraint normalization (PR #227086)

[Younan Zhang via cfe-commits]

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@@ -2532,17 +2534,13 @@ const NormalizedConstraint *Sema::getNormalizedAssociatedConstraints(
   if (CacheEntry == NormalizationCache.end()) {
     auto *Normalized = NormalizedConstraint::fromAssociatedConstraints(
         *this, ND, AssociatedConstraints);
-    if (!Normalized) {
-      NormalizationCache.try_emplace(ConstrainedDeclOrNestedReq, nullptr);
-      return nullptr;
-    }
     // substitute() can invalidate iterators of NormalizationCache.
-    bool Failed = SubstituteParameterMappings(*this).substitute(*Normalized);
+    if (Normalized &&
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zyn0217 wrote:

Yes, I followed that quirk when I wrote this...

https://github.com/llvm/llvm-project/pull/227086