[clang] [Clang][Sema] fix crash in codegen stage when an lambda expression declared in an unevaluated context (PR #80802)

[Erich Keane via cfe-commits]

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@@ -1613,8 +1613,8 @@ namespace {
 bool TemplateInstantiator::AlreadyTransformed(QualType T) {
   if (T.isNull())
     return true;
-
-  if (T->isInstantiationDependentType() || T->isVariablyModifiedType())
+  if (T->isInstantiationDependentType() || T->isVariablyModifiedType() ||
+      (SemaRef.getLangOpts().CPlusPlus20 && T->isDecltypeType()))
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erichkeane wrote:

Can you please add the relevant standards-quote here, particularly for the C++20 vs pre-C++20 change here?

https://github.com/llvm/llvm-project/pull/80802