feature gate

Author: fee1-dead

compiler/rustc_ast_passes/src/feature_gate.rs

@@ -516,6 +516,7 @@ pub fn check_crate(krate: &ast::Crate, sess: &Session, features: &Features) {
             }
         };
     }
+    gate_all!(forced_keywords, "`k#ident` syntax is experimental",);
     gate_all!(
         if_let_guard,
         "`if let` guards are experimental",

compiler/rustc_feature/src/unstable.rs

@@ -473,6 +473,8 @@ declare_features! (
     (unstable, fn_align, "1.53.0", Some(82232)),
     /// Support delegating implementation of functions to other already implemented functions.
     (incomplete, fn_delegation, "1.76.0", Some(118212)),
+    /// Support forcing an ident to be recognized as a keyword through `k#ident`.
+    (unstable, forced_keywords, "CURRENT_RUSTC_VERSION", None),
     /// Allows defining gen blocks and `gen fn`.
     (unstable, gen_blocks, "1.75.0", Some(117078)),
     /// Infer generic args for both consts and types.

compiler/rustc_parse/src/lexer/mod.rs

@@ -194,6 +194,7 @@ impl<'a> StringReader<'a> {
                 rustc_lexer::TokenKind::KeywordIdent => {
                     let sym = nfc_normalize(self.str_from(start));
                     let span = self.mk_sp(start, self.pos);
+                    self.sess.gated_spans.gate(sym::forced_keywords, span);
                     self.sess.symbol_gallery.insert(sym, span);
                     token::Ident(sym, IdentKind::Keyword)
                 }

compiler/rustc_span/src/symbol.rs

@@ -787,6 +787,7 @@ symbols! {
         fn_ptr_addr,
         fn_ptr_trait,
         forbid,
+        forced_keywords,
         forget,
         format,
         format_alignment,