[clang] [clang-tools-extra] [lldb] [clang] implement CWG1980 and CWG2064: instantiation-dependency improvements (PR #190495)

[Oliver Hunt via cfe-commits]

================
@@ -2135,6 +2136,15 @@ class alignas(TypeAlignment) Type : public ExtQualsTypeCommonBase {
     unsigned AttrKind : 32 - NumTypeBits;
   };
 
+  class DecltypeTypeBitfields {
+    friend class DecltypeType;
+
+    LLVM_PREFERRED_TYPE(TypeBitfields)
+    unsigned : NumTypeBits;
+
+    unsigned ExprCanonKind : 2;
----------------
ojhunt wrote:

preferred type please :) (I'll shut up now if there's more of this)

https://github.com/llvm/llvm-project/pull/190495