[analysis_server] Don't show expression snippets in argument names

Fixes Dart-Code/Dart-Code#4635

Change-Id: I8e8addabc7bd601ad9a9abffb87f318243255932
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/316222
Reviewed-by: Brian Wilkerson <[email protected]>
Commit-Queue: Brian Wilkerson <[email protected]>

Author: DanTup

pkg/analysis_server/lib/src/services/snippets/dart_snippet_request.dart

@@ -60,6 +60,10 @@ class DartSnippetRequest {
           tokenType == TokenType.STRING_INTERPOLATION_IDENTIFIER) {
         return SnippetContext.inString;
       }
+    } else if (entity is NamedExpression &&
+        target.offset >= entity.name.offset &&
+        target.offset <= entity.name.end) {
+      return SnippetContext.inName;
     }
 
     AstNode? node = target.containingNode;

pkg/analysis_server/lib/src/services/snippets/snippet_context.dart

@@ -20,4 +20,5 @@ enum SnippetContext {
   inQualifiedMemberAccess,
   inStatement,
   inString,
+  inName,
 }

pkg/analysis_server/test/services/snippets/snippet_request_test.dart

@@ -32,6 +32,14 @@ class A {}
 ''', SnippetContext.inAnnotation);
   }
 
+  Future<void> test_argumentName() async {
+    await testRequest(r'''
+void({required int switch}) {
+  f([!sw^!]:);
+}
+''', SnippetContext.inName);
+  }
+
   Future<void> test_block_forBody() async {
     await testRequest(r'''
 foo() {