Confusing error relating to publicity of tuple struct fields (E0603)

[Restioson]

I was struggling with a bit of code I wrote:

// mod_a
pub struct Foo(u64);

// some_other_mod
fn bar() -> ::mod_a::Foo {
    ::mod_a::Foo(10)
}

The error I got was:

error[E0603]: tuple struct `Foo` is private

Playground.

I was tearing my hair out about this -- why do I get this error? It is public?!. SuperCuber on the Rust discord helped me out by suggesting I make the field public, which solved my problem.

However, this error is misleading -- it suggests that the struct itself is private, not the field. There should perhaps be a clarifying note suggesting that the field(s) of the struct might need to be made public. It is worth noting that this error changes when you add a use ::A::Foo: playground

Meta

Affects rust playground nightly, which I assume is using the latest version.

[petrochenkov]

Same as #39703

[Restioson]

Sorry! Right, closing.