[PATCH 16/18] rust: syn: remove `unicode-ident` dependency

[Miguel Ojeda <ojeda@kernel.org>]

The `syn` crate depends on the `unicode-ident` crate to determine whether
characters have the XID_Start or XID_Continue properties according to
Unicode Standard Annex #31.

However, we only need ASCII identifiers in the kernel, thus we can
simplify the check and remove completely that dependency.

Signed-off-by: Miguel Ojeda <ojeda@kernel.org>
---
 rust/syn/ident.rs | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/rust/syn/ident.rs b/rust/syn/ident.rs
index 2c4b56505bec..03ccebf9c022 100644
--- a/rust/syn/ident.rs
+++ b/rust/syn/ident.rs
@@ -39,11 +39,11 @@ fn from(token: Token![_]) -> Ident {
 pub(crate) fn xid_ok(symbol: &str) -> bool {
     let mut chars = symbol.chars();
     let first = chars.next().unwrap();
-    if !(first == '_' || unicode_ident::is_xid_start(first)) {
+    if !(first == '_' || first.is_ascii_alphabetic()) {
         return false;
     }
     for ch in chars {
-        if !unicode_ident::is_xid_continue(ch) {
+        if !(ch == '_' || ch.is_ascii_alphanumeric()) {
             return false;
         }
     }
-- 
2.51.2