Change: Previously valid identifiers containing characters not present in UAX #44 properties XID_Start or XID_Continue, or not in Normalization Form C, are now rejected.
Rationale: Prevent confusing characters in identifiers. Requiring normalization of names ensures consistent linker behavior.
Effect on original feature: Some identifiers are no longer well-formed.
Arrg!! You can't rely on anyone these days. Oh well, at least these symbol-like characters which I've collected for use in Javascript (which has almost the same rules) should still work!
