Update to 2021 edition

Author: dtolnay

Cargo.toml

@@ -6,7 +6,7 @@ autobenches = false
 categories = ["development-tools::procedural-macro-helpers"]
 description = "A substitute implementation of the compiler's `proc_macro` API to decouple token-based libraries from the procedural macro use case."
 documentation = "https://docs.rs/proc-macro2"
-edition = "2018"
+edition = "2021"
 keywords = ["macros", "syn"]
 license = "MIT OR Apache-2.0"
 repository = "https://github.com/dtolnay/proc-macro2"

src/parse.rs

@@ -611,10 +611,10 @@ fn character(input: Cursor) -> Result<Cursor, Reject> {
 }
 
 macro_rules! next_ch {
-    ($chars:ident @ $pat:pat $(| $rest:pat)*) => {
+    ($chars:ident @ $pat:pat) => {
         match $chars.next() {
             Some((_, ch)) => match ch {
-                $pat $(| $rest)* => ch,
+                $pat => ch,
                 _ => return Err(Reject),
             },
             None => return Err(Reject),