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use_self lint suggests changing code to use outer type parameters breaking build #3859

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gnzlbg opened this issue Mar 8, 2019 · 3 comments · Fixed by #6179
Closed

use_self lint suggests changing code to use outer type parameters breaking build #3859

gnzlbg opened this issue Mar 8, 2019 · 3 comments · Fixed by #6179
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C-bug Category: Clippy is not doing the correct thing good-first-issue These issues are a good way to get started with Clippy I-suggestion-causes-error Issue: The suggestions provided by this Lint cause an ICE/error when applied L-suggestion Lint: Improving, adding or fixing lint suggestions

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@gnzlbg
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gnzlbg commented Mar 8, 2019

Here (playground):

#![crate_type = "rlib"]
#![deny(clippy::pedantic)]

pub struct Foo;
pub struct Bar([usize; 3]);

impl Foo {
    pub const BAR: usize = 3;
    
    pub fn foo() {
        const _X: usize = Foo::BAR;
        // const _Y: usize = Self::BAR;
    }
}

this example compiles, but clippy errors with

error: unnecessary structure name repetition
  --> src/lib.rs:11:27
   |
11 |         const _X: usize = Foo::BAR;
   |                           ^^^ help: use the applicable keyword: `Self`
   |

Applying the proposed fix results in a compilation error:

error[E0401]: can't use type parameters from outer function
  --> src/lib.rs:12:27
   |
7  | impl Foo {
   | ---- `Self` type implicitly declared here, by this `impl`
...
12 |         const _X: usize = Self::BAR;
   |                           ^^^^^^^^^
   |                           |
   |                           use of type variable from outer function
   |                           use a type here instead

error: aborting due to previous error
@flip1995 flip1995 added C-bug Category: Clippy is not doing the correct thing good-first-issue These issues are a good way to get started with Clippy L-suggestion Lint: Improving, adding or fixing lint suggestions I-suggestion-causes-error Issue: The suggestions provided by this Lint cause an ICE/error when applied labels Mar 8, 2019
@mati865
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mati865 commented Mar 8, 2019

The same as #2843 but it's better documented.

@marmistrz
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This happens due to this rust-lang/rust issue: rust-lang/rust#64247

tnielens added a commit to tnielens/rust-clippy that referenced this issue Apr 26, 2020
tnielens added a commit to tnielens/rust-clippy that referenced this issue Apr 26, 2020
tnielens added a commit to tnielens/rust-clippy that referenced this issue Apr 26, 2020
tnielens added a commit to tnielens/rust-clippy that referenced this issue Apr 27, 2020
flip1995 pushed a commit to flip1995/rust-clippy that referenced this issue Apr 29, 2020
bors added a commit that referenced this issue Oct 13, 2020
…itive, r=<try>

rework use_self impl based on ty::Ty comparison #3410

`use_self` lint refactoring. As suggested by `@eddyb` , implement the lint based on `ty::Ty` comparison instead of `hir::Path` checks.

This PR introduces negative regressions. The cases were covered in the previous implementation. See the test file.

It fixes #3410, #2843, #3859, #4734 and #4140. Should fix #4143 (example doesn't compile). #4305 false positive seems also fixed but the uitest fails to compile the unmodified test case in `use_self.rs.fixed`. Implements #5078.
Generally the implementation checks are done at mir level and offers higher guarantees against false positives. It is probably fixing other unreported false positives.

changelog: fix use_self generics false positives
bors added a commit that referenced this issue Jan 19, 2021
Rework use_self impl based on ty::Ty comparison #3410 | Take 2

This builds on top of #5531

I already reviewed and approved the commits by `@montrivo.` So only the review of my commits should be necessary.

I would also appreciate your review `@montrivo,` since you are familiar with the challenges here.

Fixes #3410 and Fixes #4143 (same problem)
Fixes #2843
Fixes #3859
Fixes #4734 and fixes #6221
Fixes #4305
Fixes #5078 (even at expression level now 🎉)
Fixes #3881 and Fixes #4887 (same problem)
Fixes #3909

Not yet: #4140 (test added)

All the credit for the fixes goes to `@montrivo.` I only refactored and copy and pasted his code.

changelog: rewrite [`use_self`] lint and fix multiple (8) FPs. One to go.
@jhpratt
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jhpratt commented Jan 24, 2021

For reasons I'm not entirely certain of, I can't even silence this lint on a const declaration with #[allow(clippy::use_self)].

bors added a commit that referenced this issue Feb 10, 2021
Rework use_self impl based on ty::Ty comparison #3410 | Take 2

This builds on top of #5531

I already reviewed and approved the commits by `@montrivo.` So only the review of my commits should be necessary.

I would also appreciate your review `@montrivo,` since you are familiar with the challenges here.

Fixes #3410 and Fixes #4143 (same problem)
Fixes #2843
Fixes #3859
Fixes #4734 and fixes #6221
Fixes #4305
Fixes #5078 (even at expression level now 🎉)
Fixes #3881 and Fixes #4887 (same problem)
Fixes #3909

Not yet: #4140 (test added)

All the credit for the fixes goes to `@montrivo.` I only refactored and copy and pasted his code.

changelog: rewrite [`use_self`] lint and fix multiple (8) FPs. One to go.
@bors bors closed this as completed in 605e9ba Feb 12, 2021
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Labels
C-bug Category: Clippy is not doing the correct thing good-first-issue These issues are a good way to get started with Clippy I-suggestion-causes-error Issue: The suggestions provided by this Lint cause an ICE/error when applied L-suggestion Lint: Improving, adding or fixing lint suggestions
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6 participants