[guipsp]

You are aware other languages exist? Some of which don't even use the Latin script?

[nottorp]

Dunno about the OP but I'm very aware as I'm not an english speaker.

I still don't want anything as unpredictable as Unicode in my code. How many different encodings will display as the same variable name and how is the compiler supposed to decide?

If you're thinking of comments and user facing strings, the OP already excluded those.

[cryptonector]

The language and compiler & linker should reject Zalgo in identifiers, and they should reject confusable script mixes in identifiers, but otherwise they treat all equivalent strings as equivalent. To make it easier on the linker compilers should normalize all symbols to one common form (e.g., NFC).

[account42]

And those are not programming languages, or at least not the C programming language which only needs a very limited character set.

[steveklabnik]

C does allow for limited unicode in identifiers, though you need to use the \u prefix and write the code out. Compilers like clang let it work like C++ and follow TR31, though this is nonstandard.

[Y_Y]

What; like APL‽