const_with_non_const

The constructor being called isn't a const constructor.

The analyzer produces this diagnostic when the keyword const is used to invoke a constructor that isn't marked with const.

The following code produces this diagnostic because the constructor in A isn't a const constructor:

class A {
  A();
}
​
A f() => const A();

If it's desirable and possible to make the class a constant class (by making all of the fields of the class, including inherited fields, final), then add the keyword const to the constructor:

class A {
  const A();
}
​
A f() => const A();

Otherwise, remove the keyword const:

class A {
  A();
}
​
A f() => A();