[dgrunwald]

But the source character set remains implementation-defined, so compilers do not have to directly support unicode names, only the escape notation.

Definitely a questionable choice to throw off readers with unicode weirdness in the very first code example.

[qsort]

If it were up to me, anything outside the basic character set in a source file would be a syntax error, I'm simply reporting what the spec says.

[ncruces]

I use unicode for math in comments, and think makes certain complicated formulas far more readable.

[guipsp]

What a "basic character set" is depends on locale