[clang] Patch series to reapply #118734 and substantially improve it (PR #120534)

[Eli Friedman via cfe-commits]

================
@@ -100,10 +244,17 @@ class Context {
 
   /// Return the identifier name for the specified builtin,
   /// e.g. "__builtin_abs".
-  llvm::StringRef getName(unsigned ID) const { return getRecord(ID).Name; }
+  std::string getName(unsigned ID) const;
----------------
efriedma-quic wrote:

I really don't like changing the API like this; code using the old API will be silently miscompiled when this patch lands.  Please either rename the API, or return the name in a SmallStringImpl&.

https://github.com/llvm/llvm-project/pull/120534