Pattern matching for parameters in Impl blocks does not count struct fields as used #20343

Dr-Emann · 2014-12-30T19:32:41Z

Example Code:

struct A;
struct B{ b: u32 } // warning: struct field is never used: `b`
impl A {
    fn do_stuff(&B{b}: &B) {
        println!("{}", b); // b field is used
    }
}

fn main() {
    let b = B{b:3};
    A::do_stuff(&b);
}

LeoTestard · 2015-02-07T02:32:15Z

Working on this one.

The live code analysis only visited the function's body when visiting a method, and not the FnDecl and the generics, resulting in code to be incorrectly marked as unused when it only appeared in the generics, the arguments, or the return type, whereas the same code in non-method functions was correctly detected as used. Fixes rust-lang#20343.

…kfelix The live code analysis only visited the function's body when visiting a method, and not the FnDecl and the generics, resulting in code to be incorrectly marked as unused when it only appeared in the generics, the arguments, or the return type, whereas the same code in non-method functions was correctly detected as used. Fixes rust-lang#20343. Originally I just added a call to `walk_generics` and `walk_fndecl` alongside `walk_block` but then I noticed the `walk_method_helper` function did pretty much the same thing. The only difference is that it also calls `visit_mac`, but since this is not going to happen at this stage, I think it's ok. However let me know if this was not the right thing to do.

The live code analysis only visited the function's body when visiting a method, and not the FnDecl and the generics, resulting in code to be incorrectly marked as unused when it only appeared in the generics, the arguments, or the return type, whereas the same code in non-method functions was correctly detected as used. Fixes rust-lang#20343. Originally I just added a call to `walk_generics` and `walk_fndecl` alongside `walk_block` but then I noticed the `walk_method_helper` function did pretty much the same thing. The only difference is that it also calls `visit_mac`, but since this is not going to happen at this stage, I think it's ok. However let me know if this was not the right thing to do.

kmcallister added A-lints Area: Lints (warnings about flaws in source code) such as unused_mut. A-diagnostics Area: Messages for errors, warnings, and lints E-easy Call for participation: Easy difficulty. Experience needed to fix: Not much. Good first issue. labels Jan 16, 2015

LeoTestard mentioned this issue Feb 7, 2015

Make the live code analysis visit method declarations. #22048

Merged

bors closed this as completed in #22048 Feb 12, 2015

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Pattern matching for parameters in Impl blocks does not count struct fields as used #20343

Pattern matching for parameters in Impl blocks does not count struct fields as used #20343

Dr-Emann commented Dec 30, 2014

LeoTestard commented Feb 7, 2015

Pattern matching for parameters in Impl blocks does not count struct fields as used #20343

Pattern matching for parameters in Impl blocks does not count struct fields as used #20343

Comments

Dr-Emann commented Dec 30, 2014

LeoTestard commented Feb 7, 2015