Fix hidden glob reexports 146164

[sitetester]

Fixes: #146164

The hidden_glob_reexports lint will now skip generating a warning when the imported type points to the same type as public glob reexport

Let's create the following files to check the current behaviour

Current behaviour

• fix/before/allow_when_same.rs

#![no_std] // Allows direct access to core OR Absolute path to core
#![allow(hidden_glob_reexports)]

pub use core::option::*;
use ::core::option::Option;

fn main() {
    // warning suppressed because of `allow`
    let _x: Option<i32> = Some(42);
}

• fix/before/warn_when_same.rs

#![warn(hidden_glob_reexports)]

pub use std::option::*;
use ::std::option::Option;

fn main() {
    // Warns when same (current buggy behavior)
    // Even though importing the same item & there is no "shadowing"


    // Should Only warn when a different/private item actually shadows the glob reexport
    let _x: Option<i32> = Some(42);
}

Can test using

~/rust/build/host/stage1/bin/rustc --edition 2021 fix/before/allow_when_same.rs

~/rust/build/host/stage1/bin/rustc --edition 2021 fix/before/warn_when_same.rs 

Fix

• Update compiler/rustc_resolve/src/imports.rs
• Rebuild

./x build --stage 1 # Compiler + standard library + sysroot (complete setup)

Create these files

• fix/after/not_warn_when_same.rs

#![warn(hidden_glob_reexports)]

pub use std::option::*;
use ::std::option::Option;

fn main() {
    // Should be no warning after fix
    let _x: Option<i32> = Some(42);
}

~/rust/build/host/stage1/bin/rustc --edition 2021 fix/after/not_warn_when_same.rs

• fix/after/should_warn_when_private_shadows_glob.rs

#![deny(hidden_glob_reexports)]

pub mod upstream {
    mod inner { pub struct Foo {} pub struct Bar {} }
    pub use self::inner::*;
    struct Foo {} // private item shadows `inner::Foo`
}

// mod downstream {
//     fn test() {
//         let _ = crate::upstream::Foo; // inaccessible
//     }
// }

pub fn main() {}

~/rust/build/host/stage1/bin/rustc --edition 2021 fix/after/should_warn_when_private_shadows_glob.rs

For development/quick testing,
hidden-glob-reexports-issue-146164.rs is the official test that goes into Rust, as every bug fix needs a test as per Rust standards. It's part of Rust's test suite that runs automatically

~/rust/build/host/stage1/bin/rustc ~/rust/tests/ui/lint/hidden-glob-reexports-issue-146164.rs

For official/CI testing

cd ~/rust # Must be in rust directory first  
./x test tests/ui/lint/hidden-glob-reexports-issue-146164.rs  # Use relative path

cd ~/rust 
./x test tests/ui/lint/ --test-args="146164"

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  • 2725628

[sitetester]

@petrochenkov PR is open for review.

[petrochenkov]

In the example

// mylib
pub use std::option::*;
use std::option::Option;

the lint hidden_glob_reexports should still warn because the private Option from single import will still make the public Option from glob import unavailable, and mylib::Option will result in a privacy error.

I'll close #146164.