[clang] [lldb] [BoundsSafety] Introduce LateParsedAttrType AST placeholder type (PR #204125)

[Erich Keane via cfe-commits]

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@@ -156,6 +156,9 @@ static TypeCode getTypeCodeForTypeClass(Type::TypeClass id) {
 #define TYPE_BIT_CODE(CLASS_ID, CODE_ID, CODE_VALUE) \
   case Type::CLASS_ID: return TYPE_##CODE_ID;
 #include "clang/Serialization/TypeBitCodes.def"
+  case Type::LateParsedAttr:
+    llvm_unreachable(
+        "should be replaced with a concrete type before serialization");
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erichkeane wrote:

I don't have any recommendation, TBH all of the serialization modes we have are a bit confusing.  That said, leaving these all as 'unreachable'/etc should be acceptable for now.  If we run into one,  you'll have an example on how to repro :) 

https://github.com/llvm/llvm-project/pull/204125