fix: Don't destructure struct with no public fields

[Lindronics]

Unfortunately I missed this case in #16638.

If a struct only has private members, the assist should not be applicable. Though valid syntax exists (Foo { .. }), it isn't particularly useful. Since this case applies to a lot of common types (Arc, Vec, ...), it probably makes the most sense to hide the action.

As a side effect, this also disables the action for unit structs, where it also isn't particularly useful. I'd be open to changing it though if you think it makes more sense to keep it.

This also fixes the make::record_pat_field_list function to produce valid syntax if the field list is empty, as it is used in other places too.

Current behaviour

// In crate `other_crate`
pub struct Foo { bar: i32 }

// In current crate
fn do_something(foo: other_crate::Foo) {}

// Becomes
fn do_something(other_crate::Foo { , .. }: other_crate::Foo) {}

Fixed behaviour

Assist should not be applicable in this case anymore.

[Veykril]

Thanks!

[Veykril]

@bors r+

[bors]

📌 Commit 2a4ba42 has been approved by Veykril

It is now in the queue for this repository.

[bors]

⌛ Testing commit 2a4ba42 with merge 0c2e9fe...

[bors]

☀️ Test successful - checks-actions
Approved by: Veykril
Pushing 0c2e9fe to master...