Errantly formatting multiline macro

[fpdotmonkey]

I have this macro call here that is formatted by rustfmt as so.

$ rustfmt --check godot-macros/src/class/data_models/field_export.rs
Diff in /home/fp/3rd/gdext/godot-macros/src/class/data_models/field_export.rs at line 402:
                 }?;
                 let deprecation_warning = if *radians {
                     quote! {
-			#export_func;
-			::godot::__deprecated::emit_deprecated_warning!(export_range_radians);
-                    }
+                    #export_func;
+                    ::godot::__deprecated::emit_deprecated_warning!(export_range_radians);
+                            }
                 } else {
                     quote! { #export_func }
                 };
$ rustfmt --version
rustfmt 1.7.0-stable (129f3b9 2024-06-10)

You can see here that rustfmt wants to un-indent the macro contents and double indent the end bracket for some reason.

Here's aa MCVE for this issue. The important details are that the innermost expressions are within a curly bracket-delimited macro, which itself is within 3 levels of scope.

// correct formatting
fn bar() {
    {
        {
            foo! {
		export_func;
                warning;
            }
        }
    }
}

// rustfmt output
fn bar() {
    {
        {
            foo! {
            export_func;
                    warning;
                }
        }
    }
}

[fpdotmonkey]

Hey I'm continuing to get errors related to this. I'd be happy to do some work to come up with better reproduction steps, but I'd need help from a maintainer to figure out how.

[ytmimi]

@fpdotmonkey I'm also unable to reproduce the issue that you described. Are you using any other configuration options? Also, what version of rustc are you using?

[fpdotmonkey]

Here's some version and config information

$ rustfmt --version
rustfmt 1.7.0-stable (3f5fd8d 2024-08-06)
$ rustc --version
rustc 1.80.1 (3f5fd8dd4 2024-08-06)
$ cat ~/.rustfmt.toml 
edition = "2021"
$ cat ~/rustfmt.toml
cat: /home/fp/rustfmt.toml: No such file or directory
$ ls ~/.config/rustfmt
ls: cannot access '/home/fp/.config/rustfmt': No such file or directory

So rustc and rustfmt are installed the regular way through rustup, and the only config I have is a more recent edition. I did previously have edition = "2024" instead of 2021 in the config, but the issue occurs regardless of that and also if I specify the edition in the cli, --edition 2021.

[fpdotmonkey]

It's also worth noting that the CI for the project I've referenced would fail if it caught a diff from rustfmt, so it's at least reproducing that the above formatting isn't corrected to the intuitively correct one.

[ytmimi]

@fpdotmonkey if you change the formatting to what you expect it to be does CI pass or does CI fail when it checks formatting?

[fpdotmonkey]

It's hard to say with the particular problem that's referenced at the top of this issue; that was merged months ago. I encountered something that's possibly related in godot-rust/gdext#876 (comment), and that does fail on account of rustfmt https://github.com/godot-rust/gdext/actions/runs/10655828310/job/29533814938?pr=876

[ytmimi]

If you're able to put together a minimal reproduction for the new snippet that you've linked to that would be great

[fpdotmonkey]

Sure thing. This is a bit different from what occurs in that comment. There, only the #[doc] macros are one tab too little indent, but here, it's the whole quote! body that's one level too little.

// manual formatting
fn main() {
    let functions = quote! {
	#[doc = "Documentation"]
	#[inline]
	fn foo() {}
    };
}

// rustfmt output from the previous snippet
fn main() {
    let functions = quote! {
    #[doc = "Documentation"]
    #[inline] // In the issue that I encountered, here and below was indented one tab further, which would be correct
    fn foo() {}
    };
}

I'm not sure why this is different from the linked example, but it's at least reproducible and similar behavior.

[fpdotmonkey]

I did a little more probing at the wrong formatting from the top of this issue and was able to create a MCVE.

// correct formatting
fn bar() {
    {
        {
            foo! {
		export_func;
                warning;
            }
        }
    }
}

// rustfmt output
fn bar() {
    {
        {
            foo! {
            export_func;
                    warning;
                }
        }
    }
}

Notes on this:

• It's required that there be a macro call---replacing it with scope, conditions, or similar won't cause the issue
• It's required that the macro have curly bracket invocation---parentheses and square brackets won't reproduce
• It's required that the macro is contained within 3 or more levels of scope
• The scope can come from conditions, functions, trait impls, or inherent impls (at least)
• There's also an odd behavior where if I replace foo! with if foo, it will format correctly (expected), but then when I change it back from if foo to foo!, it won't reproduce, despite being the same code as the initial sample. If I clear the buffer and paste in the above example, it will reproduce again.

[fpdotmonkey]

Hey is there anything more needed for a MCVE?