unreachable_from_main

Unreachable member '{0}' in an executable library.

The analyzer produces this diagnostic when a public declaration in an executable library isn't referenced, directly or indirectly, from an entry point of that library.

An executable library is a library that contains an entry point. An entry point is a top-level function that is one of the following:

• Named main.
• Annotated with @pragma('vm:entry-point').
• Annotated with Flutter's widget preview annotation, @Preview.

The analyzer doesn't report declarations annotated with @visibleForTesting from package:meta or @Preview from Flutter.

The following code produces this diagnostic because the function f is not referenced from the main function:

void main() {}
​
void f() {}

The following code produces this diagnostic because the method m is not referenced, even though its containing class C is:

void main() {
  C();
}
​
class C {
  void m() {}
}

If the declaration is intended to be used, then add the missing reference:

void main() {
  f();
}
​
void f() {}

If the declaration isn't needed, then remove it:

void main() {}

If the declaration is public in order to be used by tests, then add the @visibleForTesting annotation:

import 'package:meta/meta.dart';
​
void main() {}
​
@visibleForTesting
void f() {}