Merge pull request #1836 from nmote/extra-alias

Avoid extracting default alias for extras

cli/src/generate/prepare_grammar/extract_default_aliases.rs

@@ -62,6 +62,18 @@ pub(super) fn extract_default_aliases(
         }
     }
 
+    for symbol in syntax_grammar.extra_symbols.iter() {
+        let mut status = match symbol.kind {
+            SymbolType::External => &mut external_status_list[symbol.index],
+            SymbolType::NonTerminal => &mut non_terminal_status_list[symbol.index],
+            SymbolType::Terminal => &mut terminal_status_list[symbol.index],
+            SymbolType::End | SymbolType::EndOfNonTerminalExtra => {
+                panic!("Unexpected end token")
+            }
+        };
+        status.appears_unaliased = true;
+    }
+
     let symbols_with_statuses = (terminal_status_list
         .iter_mut()
         .enumerate()

test/fixtures/test_grammars/aliased_rules/corpus.txt

@@ -2,11 +2,12 @@
 Method calls
 ======================================
 
-a.b(c(d.e));
+*a.b(c(d.e));
 
 ---
 
 (statement
+  (star)
   (call_expression
     (member_expression
       (variable_name)

test/fixtures/test_grammars/aliased_rules/grammar.js

@@ -1,7 +1,10 @@
 module.exports = grammar({
     name: 'aliased_rules',
 
-    extras: $ => [/\s/],
+    extras: $ => [
+      /\s/,
+      $.star,
+    ],
 
     rules: {
         statement: $ => seq($._expression, ';'),
@@ -25,6 +28,15 @@ module.exports = grammar({
             alias($.identifier, $.property_name)
         )),
 
-        identifier: $ => /[a-z]+/
+        identifier: $ => /[a-z]+/,
+
+        // Tests for https://github.com/tree-sitter/tree-sitter/issues/1834
+        //
+        // Even though the alias is unused, that issue causes all instances of
+        // the extra that appear in the tree to be renamed to `star_aliased`.
+        //
+        // Instead, this alias should have no effect because it is unused.
+        star: $ => '*',
+        unused: $ => alias($.star, $.star_aliased),
     }
-});
+});