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huonw opened this issue Oct 13, 2014 · 2 comments
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Unused variables inside for are not detected #17999

huonw opened this issue Oct 13, 2014 · 2 comments
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A-diagnostics Area: Messages for errors, warnings, and lints A-lints Area: Lints (warnings about flaws in source code) such as unused_mut.

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@huonw
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huonw commented Oct 13, 2014 

fn main() {
    for _ in range(1i, 101) {
        let x = ();
        match () {
            a => {}
        }
    }
}

compiles without a peep, even though x and a are unused. Commenting out the for gives the expected output:

<anon>:3:13: 3:14 warning: unused variable: `x`, #[warn(unused_variable)] on by default
<anon>:3         let x = ();
                     ^
<anon>:5:13: 5:14 warning: unused variable: `a`, #[warn(unused_variable)] on by default
<anon>:5             a => {}
                     ^
@huonw huonw added I-wrong A-lints Area: Lints (warnings about flaws in source code) such as unused_mut. A-diagnostics Area: Messages for errors, warnings, and lints labels Oct 13, 2014
@hirschenberger hirschenberger mentioned this issue Oct 13, 2014
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hirschenberger added a commit to hirschenberger/rust that referenced this issue Oct 13, 2014
@hirschenberger
Fix issue rust-lang#17999 (Unused variables inside for are not dete…
af2f538 
…cted)
bors added a commit that referenced this issue Oct 14, 2014
@bors
auto merge of #18014 : hirschenberger/rust/issue-17999, r=alexcrichton
1fd8e4c 
Fix issue #17999 (Unused variables inside `for` are not detected)
@hirschenberger
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I think this an be closed

@alexcrichton
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Thanks @hirschenberger (fixed in #18014)

lnicola pushed a commit to lnicola/rust that referenced this issue Sep 25, 2024
@bors
Auto merge of rust-lang#17999 - ShoyuVanilla:issue-17998, r=Veykril
a729229 
fix: `std::error::Error` is object unsafe

Fixes rust-lang#17998

I tried to get generic predicates of assoc function itself, not inherited from the parent here;

https://github.com/rust-lang/rust-analyzer/blob/0ae42bd42576566540a84c62e118aa823edcf2ec/crates/hir-ty/src/object_safety.rs#L420-L442

But this naive equality check approach doesn't work when the assoc function has one or more generic paramters like;

```rust
trait Foo {}
trait Bar: Foo {
    fn bar(&self);
}
```

because the generic predicates of the parent, `Bar` is `[^1.0 implements Foo]` and the generic predicates of `fn bar` is `[^1.1 implements Foo]`, which are different.

This PR implements a correct logic for filtering out parent generic predicates for this.
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A-diagnostics Area: Messages for errors, warnings, and lints A-lints Area: Lints (warnings about flaws in source code) such as unused_mut.
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