Add test for nfc-normalization of idents

tests/ui/lexer/ident_normalization.rs

@@ -0,0 +1,20 @@
+//@check-pass
+//@edition:2021
+
+#![allow(non_snake_case)]
+
+// Tests that identifiers are NFC-normalized as per
+// https://rust-lang.github.io/rfcs/2457-non-ascii-idents.html
+
+// Note that in the first argument of each function `K` is LATIN CAPITAL LETTER K
+// and in the second it is K (KELVIN SIGN).
+
+fn ident_nfc<K>(_p1: K, _p2: K) {}
+
+fn raw_ident_nfc<K>(_p1: r#K, _p2: r#K) {}
+
+fn lifetime_nfc<'K>(_p1: &'K str, _p2: &'K str) {}
+
+fn raw_lifetime_nfc<'K>(_p1: &'r#K str, _p2: &'r#K str) {}
+
+fn main() {}