Remove gen keyword.

This is blocking testing.

Author: ehuss

compiler/rustc_parse/src/parser/expr.rs

@@ -1519,15 +1519,15 @@ impl<'a> Parser<'a> {
                 Ok(this.mk_expr(this.prev_token.span, ExprKind::Underscore))
             } else if this.token.uninterpolated_span().at_least_rust_2018() {
                 // `Span::at_least_rust_2018()` is somewhat expensive; don't get it repeatedly.
-                if this.token.uninterpolated_span().at_least_rust_2024()
-                    // check for `gen {}` and `gen move {}`
-                    // or `async gen {}` and `async gen move {}`
-                    && (this.is_gen_block(kw::Gen, 0)
-                        || (this.check_keyword(kw::Async) && this.is_gen_block(kw::Gen, 1)))
-                {
-                    // FIXME: (async) gen closures aren't yet parsed.
-                    this.parse_gen_block()
-                } else if this.check_keyword(kw::Async) {
+                // if this.token.uninterpolated_span().at_least_rust_2024()
+                //     // check for `gen {}` and `gen move {}`
+                //     // or `async gen {}` and `async gen move {}`
+                //     && (this.is_gen_block(kw::Gen, 0)
+                //         || (this.check_keyword(kw::Async) && this.is_gen_block(kw::Gen, 1)))
+                // {
+                //     // FIXME: (async) gen closures aren't yet parsed.
+                //     this.parse_gen_block()
+                if this.check_keyword(kw::Async) {
                     // FIXME(gen_blocks): Parse `gen async` and suggest swap
                     if this.is_gen_block(kw::Async, 0) {
                         // Check for `async {` and `async move {`,

compiler/rustc_parse/src/parser/mod.rs

@@ -1202,14 +1202,14 @@ impl<'a> Parser<'a> {
                     return_impl_trait_id: DUMMY_NODE_ID,
                 })
             }
-        } else if self.token.uninterpolated_span().at_least_rust_2024()
-            && self.eat_keyword_case(kw::Gen, case)
-        {
-            Some(CoroutineKind::Gen {
-                span,
-                closure_id: DUMMY_NODE_ID,
-                return_impl_trait_id: DUMMY_NODE_ID,
-            })
+        // } else if self.token.uninterpolated_span().at_least_rust_2024()
+        //     && self.eat_keyword_case(kw::Gen, case)
+        // {
+        //     Some(CoroutineKind::Gen {
+        //         span,
+        //         closure_id: DUMMY_NODE_ID,
+        //         return_impl_trait_id: DUMMY_NODE_ID,
+        //     })
         } else {
             None
         }

compiler/rustc_span/src/symbol.rs

@@ -2380,7 +2380,7 @@ impl Symbol {
 
     fn is_unused_keyword_conditional(self, edition: impl Copy + FnOnce() -> Edition) -> bool {
         self == kw::Try && edition().at_least_rust_2018()
-            || self == kw::Gen && edition().at_least_rust_2024()
+        // || self == kw::Gen && edition().at_least_rust_2024()
     }
 
     pub fn is_reserved(self, edition: impl Copy + FnOnce() -> Edition) -> bool {