Primary constructor parameters that are not properties does not give an error with explicit constructor

[TorRanfelt]

Why do I get the error "This class is not serializable automatically because it has primary constructor parameters of which are not properties" in example A when B doesn't?

A:

@Serializable
class Foo(bar: Int) {
    val baz: Int

    init {
        baz = bar
    }
}

B:

@Serializable
class Foo {
    val baz: Int

    constructor(bar: Int) {
        baz = bar
    }
}

[lpi]

has there been any work on this? it blocks @JsExport due to the secondary constructor, which makes things annoying

[pdvrieze]

Version B (without primary constructor) allows a serialization specific constructor to be generated. Unfortunately the plugin isn't smart enough to recognize that the bar parameter of the primary constructor actually corresponds to the baz property and as such it complains that it cannot create valid instances.

[sandwwraith]

@lpi Secondary constructors shouldn't block the ability of class being @Serializable. If you have problems with them, please file new issue

[sandwwraith]

We do not plan to implement this diagnostic — original 'Primary constructor parameters that are not properties' was intended for cases where the parameter is used in the initializer for, say, @Transient val. Parameters from in-body constructors are not allowed to be used in initializers for properties, so it doesn't block them from being correctly initialized by serialization plugin.