Stabilize joinir tests and env guards

src/parser/statements/mod.rs

@@ -214,6 +214,22 @@ impl NyashParser {
     pub(super) fn parse_statement(&mut self) -> Result<ASTNode, ParseError> {
         // For grammar diff: capture starting token to classify statement keyword
         let start_tok = self.current_token().token_type.clone();
+        if !crate::config::env::parser_stage3_enabled() {
+            if let TokenType::IDENTIFIER(name) = &start_tok {
+                let is_stage3_keyword = matches!(
+                    name.as_str(),
+                    "local" | "flow" | "try" | "catch" | "cleanup" | "throw" | "while" | "for"
+                        | "in"
+                );
+                if is_stage3_keyword {
+                    return Err(ParseError::UnexpectedToken {
+                        found: start_tok.clone(),
+                        expected: "enable NYASH_FEATURES=stage3 for Stage-3 keywords".to_string(),
+                        line: self.current_token().line,
+                    });
+                }
+            }
+        }
 
         let result = match &start_tok {
             TokenType::LBRACE => self.parse_standalone_block_statement(),