cargo fmt stopped working since 1.44.0

[xStrom]

I'm trying to format code for the druid project.
Everything was working fine up until Rust 1.43.1 / rustfmt 1.4.12-stable (a828ffe 2020-03-11).

It no longer works properly with:
Rust 1.44.0 / rustfmt 1.4.14-stable (e417356 2020-04-21)
Rust 1.44.1 / rustfmt 1.4.16-stable (939e164 2020-06-11)

It does not seem to be platform dependant, the issue exists at minimum both on Windows 7 and macOS Catalina, and not just my machines.

The druid workspace consists of several packages including druid-shell which is the package that is problematic.

If I run cargo fmt inside the druid-shell package root then it works.

The problem is with using cargo fmt or cargo fmt --all in the workspace directory.
That used to also work, but now works only partially on druid-shell.

Some of the modules get formatted while others don't.
It seems to have something to do with the cfg-if macro.

A file of interest is druid-shell/src/platform/mod.rs, which has the following code:

cfg_if::cfg_if! {
    if #[cfg(target_os = "windows")] {
        mod windows;
        pub use windows::*;
    } else if #[cfg(target_os = "macos")] {
        mod mac;
        pub use mac::*;
    } else if #[cfg(all(feature = "x11", target_os = "linux"))] {
        mod x11;
        pub use x11::*;
    } else if #[cfg(target_os = "linux")] {
        mod gtk;
        pub use self::gtk::*;
    } else if #[cfg(target_arch = "wasm32")] {
        mod web;
        pub use web::*;
    }
}

If I delete that macro and replace it with a simple:

mod windows;
pub use windows::*;

Then the windows module gets formatted when I run cargo fmt in the workspace directory. However if the cfg-if macro is there, then none of these platform modules get formatted. Again, this is a recent regression and previously all those platform modules got formatted.

Any insight would be appreciated.

[topecongiro]

MWE:

rustfmt -cr \
        druid/examples/web/src/lib.rs \
        druid-shell/src/lib.rs

However, the below works correctly 🤔

rustfmt -cr \
        druid-shell/src/lib.rs

[calebcartwright]

I'm not sure we've ever fully supported this scenario (see #3253), even though I've convinced myself on a few occasions that we were previously close 😆

Also FWIW, I'm able to reproduce the issue with rustfmt 1.4.12 in identical cfg_if scenarios

[calebcartwright]

It's also fixed in rustfmt 1.4.18 and on master/rustfmt 2.0.

rustfmt 1.4.14 was the first rustfmt release that had to incorporate the fallout from the upstream parse/expansion split in rustc, and there were a few parser/mod resolution bugs that snuck through in rustfmt 1.4.14 and 1.4.16 that I'm guessing may be the culprit here.

(rustfmt 1.4.18 will hit nightly once rust-lang/rust/pull/73506 lands)

Disregard ☝️

[topecongiro]

@calebcartwright I don't think this is fixed on the master; I can still reproduce this locally using the master branch.

---

This seems the problem:

rustfmt/src/formatting/modules.rs

Lines 24 to 26 in 5ac191d

	lazy_static! {
	static ref CFG_IF: Symbol = Symbol::intern("cfg_if");
	}

The CFG_IF is somehow changed to //! after formatting druid/examples/web/src/lib.rs. I have no idea why 🤷

[calebcartwright]

well that's puzzling 🤔 I'll check again with 2.0

I'm pretty confident that 1.4.18 is fine though (confident, but wrong!)

$ cargo fmt --version
rustfmt 1.4.18-nightly (c1e9b7b8 2020-06-13)
$ pwd
/home/caleb/dev/druid
$ cargo fmt -- --check
Diff in /home/caleb/dev/druid/druid-shell/src/window.rs at line 14:
 
 //! Platform independent window types.
 
-    use std::any::Any;
+use std::any::Any;
 use std::time::Duration;
 
 use _crate::application::Application;_

[topecongiro]

@calebcartwright You are modifying the wrong file 😉 You should change one of the files under druid-shell/src/platform/ other than mod.rs.

[calebcartwright]

crikey 🤦‍♂️

sorry for the noise! I started looking at this earlier but had to stop, and assumed I had the right file up when I came back 😆