[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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@@ -1614,7 +1614,19 @@ bool TemplateInstantiator::AlreadyTransformed(QualType T) {
   if (T.isNull())
     return true;
 
-  if (T->isInstantiationDependentType() || T->isVariablyModifiedType())
+  bool DependentLambdaType = false;
+  QualType DesugaredType = T.getDesugaredType(SemaRef.getASTContext());
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erichkeane wrote:

Is this step necessary?  `getAsCXXRecordDecl` should at least canonicalize.  

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