invocation_of_extension_without_call

The extension '{0}' doesn't define a 'call' method so the override can't be used in an invocation.

The analyzer produces this diagnostic when an extension override is used to invoke a function but the extension doesn't declare a call method.

The following code produces this diagnostic because the extension E doesn't define a call method:

extension E on String {}

void f() {
  E('')();
}

If the extension is intended to define a call method, then declare it:

extension E on String {
  int call() => 0;
}

void f() {
  E('')();
}

If the extended type defines a call method, then remove the extension override.

If the call method isn't defined, then rewrite the code so that it doesn't invoke the call method.

Unless stated otherwise, the documentation on this site reflects Dart 3.8.0. Page last updated on 2025-05-08. View source or report an issue.