Bump proc-macro2 in xtask

Cargo.lock

@@ -1408,9 +1408,9 @@ dependencies = [
 
 [[package]]
 name = "proc-macro2"
-version = "1.0.86"
+version = "1.0.93"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "5e719e8df665df0d1c8fbfd238015744736151d4445ec0836b8e628aae103b77"
+checksum = "60946a68e5f9d28b0dc1c21bb8a97ee7d018a8b322fa57838ba31cc878e22d99"
 dependencies = [
  "unicode-ident",
 ]

xtask/Cargo.toml

@@ -16,8 +16,7 @@ xflags = "0.3.0"
 time = { version = "0.3", default-features = false }
 zip = { version = "0.6", default-features = false, features = ["deflate", "time"] }
 stdx.workspace = true
-# https://github.com/dtolnay/proc-macro2/issues/475
-proc-macro2 = "=1.0.86"
+proc-macro2 = "1.0.93"
 quote = "1.0.20"
 ungrammar = "1.16.1"
 either.workspace = true

xtask/src/codegen/grammar.rs

@@ -397,6 +397,9 @@ fn generate_syntax_kinds(grammar: KindsSrc) -> String {
         if "{}[]()".contains(token) {
             let c = token.chars().next().unwrap();
             quote! { #c }
+            // underscore is an identifier in the proc-macro api
+        } else if *token == "_" {
+            quote! { _ }
         } else {
             let cs = token.chars().map(|c| Punct::new(c, Spacing::Joint));
             quote! { #(#cs)* }