Skip to content
New issue

Have a question about this project? Sign up for a free GitHub account to open an issue and contact its maintainers and the community.

By clicking “Sign up for GitHub”, you agree to our terms of service and privacy statement. We’ll occasionally send you account related emails.

Already on GitHub? Sign in to your account

Rustfmt wrongly reformats qualified paths in a match expression in macro #4908

Closed
tvercruyssen opened this issue Jul 18, 2021 · 1 comment · Fixed by #4964
Closed

Rustfmt wrongly reformats qualified paths in a match expression in macro #4908

tvercruyssen opened this issue Jul 18, 2021 · 1 comment · Fixed by #4964

Comments

@tvercruyssen
Copy link

Describe the bug

Rustfmt incorrectly formats the new qualified paths in a match expression, in a macro. The change rustfmt makes will make the code no longer compile.

To Reproduce

minimal example:

#![feature(more_qualified_paths)]

mod foo_bar {
    pub enum Example {
        Example1 {},
        Example2 {},
    }
}

fn main() {
    foo!(crate::foo_bar::Example, Example1);

    let i1 = foo_bar::Example::Example1{};

    assert_eq!(i1.foo_example(), 1);

    let i2 = foo_bar::Example::Example2{};

    assert_eq!(i2.foo_example(), 2);

}

#[macro_export]
macro_rules! foo {
    ($struct:path, $variant:ident) => {
        impl $struct {
            pub fn foo_example(&self) -> i32{
                match self {
                    <$struct>::$variant { .. } =>  1,
                    _ => 2,
                }
            }
        }
    };
}

This will compile fine. After running rustfmt the diff is as follows:

@@ -25,7 +25,7 @@
         impl $struct {
             pub fn foo_example(&self) -> i32 {
                 match self {
-                    <$struct>::$variant { .. } => 1,
+                    $variant { .. } => 1,
                     _ => 2,
                 }
             }

This makes the code no longer compile and gives the following error:

error[E0422]: cannot find struct, variant or union type `Example1` in this scope
  --> src/main.rs:11:35
   |
11 |     foo!(crate::foo_bar::Example, Example1);
   |                                   ^^^^^^^^ not found in this scope
   |
help: consider importing this variant
   |
3  | use crate::foo_bar::Example::Example1;
   |

No rustfmt configuration was used.

Expected behavior

Rustfmt should not reformat anything.

Meta

  • tested with both:
    • stable: rustfmt 1.4.37-stable (2a3635d 2021-05-04)
    • nightly: rustfmt 1.4.37-nightly (c7331d6 2021-07-17)
  • From where did you install rustfmt?: rustup
  • How do you run rustfmt: rustfmt src/main.rs
[Sidenote]

I'm aware instead of writing <$struct>::$variant, you could write Self::$variant. This will compile and not be reformatted by rustfmt in this case. But in cases where the impl struct and match expression are not on the same this will not work.

[Disclaimer] This is a nightly feature.
@calebcartwright
Copy link
Member

Thanks for the report!

Sign up for free to join this conversation on GitHub. Already have an account? Sign in to comment
Projects
None yet
Development

Successfully merging a pull request may close this issue.

2 participants