E4001

A field with incompatible visibility cannot be declared within a struct.

The following visibility combinations are allowed:

• A public field within a public struct, although it will emit a warning E1008.

• A private field within a public struct.

• A private field within a private struct, emitting E1008 as well.

Erroneous Example

priv struct S {
  pub field: Int
}

This example declares a field with public visibility within a struct with private visibility, which is not allowed and will give the following error on line 2:

A public field cannot be declared within a private struct.

Suggestion

Change the visibility of the field to match the visibility of the struct:

priv struct S {
  field: Int
}

We could have written priv field: Int instead of field: Int as well, but it is not necessary, as all fields in a private struct are private by default.