Detect tuple structs that are unconstructable due to re-export

[estebank]

When a tuple-struct is re-exported that has inaccessible fields at the use scope, the type's constructor cannot be accessed through that re-export. We now account for this case and extend the resulting resolution error. We also check if the constructor would be accessible directly, not through the re-export, and if so, we suggest using the full path instead.

error[E0423]: cannot initialize a tuple struct which contains private fields
  --> $DIR/ctor-not-accessible-due-to-inaccessible-field-in-reexport.rs:12:33
   |
LL |             let crate::Foo(x) = crate::Foo(42);
   |                                 ^^^^^^^^^^
   |
note: the type is accessed through this re-export, but the type's constructor is not visible in this import's scope due to private fields
  --> $DIR/ctor-not-accessible-due-to-inaccessible-field-in-reexport.rs:3:9
   |
LL | pub use my_mod::Foo;
   |         ^^^^^^^^^^^
help: the type can be constructed directly, because its fields are available from the current scope
   |
LL |             let crate::Foo(x) = crate::my_mod::Foo(42);
   |                                 ~~~~~~~~~~~~~~~~~~

Fix #133343.

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[wesleywiser]

r? rust-lang/compiler

[davidtwco]

@bors r+ rollup

[bors]

📌 Commit 4063732 has been approved by davidtwco

It is now in the queue for this repository.

[davidtwco]

@bors r- needs a rebase