Filter LSP definitions to not include variable names

Fixes Dart-Code/Dart-Code#2535.

Change-Id: I2e64d0cd53abcde4ac3ecae1682b6b054b16407a
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/150980
Commit-Queue: Danny Tuppeny <[email protected]>
Reviewed-by: Brian Wilkerson <[email protected]>

Author: DanTup

pkg/analysis_server/lib/src/lsp/handlers/handler_definition.dart

@@ -92,7 +92,21 @@ class DefinitionHandler
           return navigationTargetToLocation(targetFilePath, target, lineInfo);
         }
 
-        return success(convert(mergedTargets, toLocation).toList());
+        final results = convert(mergedTargets, toLocation).toList();
+
+        // If we fetch navigation on a keyword like `var`, the results will include
+        // both the definition and also the variable name. This will cause the editor
+        // to show the user both options unnecessarily (the variable name is always
+        // adjacent to the var keyword, so providing navigation to it is not useful).
+        // To prevent this, filter the list to only those on different lines (or
+        // different files).
+        final otherResults = results
+            .where((element) =>
+                element.uri != params.textDocument.uri ||
+                element.range.start.line != pos.line)
+            .toList();
+
+        return success(otherResults.isNotEmpty ? otherResults : results);
       });
     });
   }

pkg/analysis_server/test/lsp/definition_test.dart

@@ -86,6 +86,21 @@ class DefinitionTest extends AbstractLspAnalysisServerTest {
     expect(res, isEmpty);
   }
 
+  Future<void> test_sameLine() async {
+    final contents = '''
+    int plusOne(int [[value]]) => 1 + val^ue;
+    ''';
+
+    await initialize();
+    await openFile(mainFileUri, withoutMarkers(contents));
+    final res = await getDefinition(mainFileUri, positionFromMarker(contents));
+
+    expect(res, hasLength(1));
+    var loc = res.single;
+    expect(loc.range, equals(rangeFromMarkers(contents)));
+    expect(loc.uri, equals(mainFileUri.toString()));
+  }
+
   Future<void> test_singleFile() async {
     final contents = '''
     [[foo]]() {
@@ -119,4 +134,21 @@ class DefinitionTest extends AbstractLspAnalysisServerTest {
     expect(loc.range, equals(rangeFromMarkers(contents)));
     expect(loc.uri, equals(mainFileUri.toString()));
   }
+
+  Future<void> test_varKeyword() async {
+    final contents = '''
+    va^r a = MyClass();
+
+    class [[MyClass]] {}
+    ''';
+
+    await initialize();
+    await openFile(mainFileUri, withoutMarkers(contents));
+    final res = await getDefinition(mainFileUri, positionFromMarker(contents));
+
+    expect(res, hasLength(1));
+    var loc = res.single;
+    expect(loc.range, equals(rangeFromMarkers(contents)));
+    expect(loc.uri, equals(mainFileUri.toString()));
+  }
 }