[clang] [Serialization] Handle uninitialized type constraints (PR #110496)

[via cfe-commits]

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@@ -1899,7 +1899,7 @@ void ASTDeclWriter::VisitTemplateTypeParmDecl(TemplateTypeParmDecl *D) {
   Record.push_back(D->wasDeclaredWithTypename());
 
   const TypeConstraint *TC = D->getTypeConstraint();
-  assert((bool)TC == D->hasTypeConstraint());
+  Record.push_back(/*TypeConstraintInitialized=*/TC != nullptr);
   if (TC) {
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cor3ntin wrote:

What about checking for `D->hasTypeConstraint()` instead of pushing am additional bool?

https://github.com/llvm/llvm-project/pull/110496