[analysis_server] Fix finding references for the offset between a typ…

…e name and generic type parameters

Fixes Dart-Code/Dart-Code#4668

Change-Id: Ibdb45b5c09ab8de0746239e351b5e581af4bb7df
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/317080
Reviewed-by: Brian Wilkerson <brianwilkerson@google.com>
Commit-Queue: Brian Wilkerson <brianwilkerson@google.com>

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

@@ -64,7 +64,8 @@ class ReferencesHandler
       ReferenceParams params,
       ResolvedUnitResult unit,
       OperationPerformanceImpl performance) async {
-    final node = NodeLocator(offset).searchWithin(result.unit);
+    var node = NodeLocator(offset).searchWithin(result.unit);
+    node = _getReferenceTargetNode(node);
     var element = server.getElementOfNode(node);
     if (element == null) {
       return success(null);
@@ -104,4 +105,24 @@ class ReferencesHandler
 
     return success(referenceResults);
   }
+
+  /// Gets the nearest node that should be used for finding references.
+  ///
+  /// This is usually the same node but allows some adjustments such as
+  /// considering the offset between a type name and type arguments as part
+  /// of the type.
+  AstNode? _getReferenceTargetNode(AstNode? node) {
+    // Consider the angle brackets for type arguments part of the leading type,
+    // otherwise we don't navigate in the common situation of having the type
+    // name selected, where VS Code provides the end of the selection as the
+    // position to search.
+    //
+    // In `A^<String>` node will be `TypeParameterList` and we will not find any
+    // references.
+    if (node is TypeParameterList) {
+      node = node.parent;
+    }
+
+    return node;
+  }
 }

pkg/analysis_server/test/lsp/references_test.dart

@@ -178,6 +178,26 @@ f^oo() {
     await _checkRanges(content, includeDeclarations: false);
   }
 
+  Future<void> test_type() async {
+    final content = '''
+class A^aa<T> {}
+
+[!Aaa!]<String>? a;
+''';
+
+    await _checkRanges(content);
+  }
+
+  Future<void> test_type_generic_end() async {
+    final content = '''
+class Aaa^<T> {}
+
+[!Aaa!]<String>? a;
+''';
+
+    await _checkRanges(content);
+  }
+
   Future<void> test_unopenFile() async {
     final code = TestCode.parse('''
     f^oo() {