normalize_doc_attributes sometimes comments out code

[olivia-fl]

The simplest test case I've been able to come up with so far is this:

mod a {
    mod b {
        #[doc = "test"]fn foo() -> () { }
    }
}

with config

normalize_doc_attributes=true
max_width=10

This example gets reformatted to the following, although it does report an error because the line exceeds the maximum width.

mod a {
    mod b {
        ///testfn foo() -> (){
        }
    }
}

I'm still not sure exactly what triggers this bug, but have found a lot of variants for this example which don't trigger it. Here are a few that might be significant:

#[doc = "test"]fn foo() -> () { }

mod a {
    mod b {
        #[doc = "test"]fn foo() { }
    }
}

mod a {
    mod b {
        #[doc = "test"]
        fn foo() -> () { }
    }
}

mod a {
    mod b {
        /// test
        fn foo() -> () { }
    }
}

In these examples, removing max_width=10 fixes the issue, but I encountered this originally in a situation where rustfmt was inexplicably being run on autogenerated files in the target directory that were part of the wayland-protocol crate. I haven't figured out what was causing rustfmt to process those files in the first place, but in that case I did have max_width=80 instead.

I have no clue what's happening or how to fix it at this point, but I'm pretty sure it has to do with formatting lines that are longer than max_width combined with some unknown other requirement. I'll try to look into this more soon and see if I can figure out how to fix it.

[elinorbgr]

An other example that triggers this:

This original (generated) code:

pub mod zwp_fullscreen_shell_v1 { impl ZwpFullscreenShellV1 { # [ doc = "present surface for display at a particular mode\n\nIf the value of wl_output.scale differs from wl_surface.buffer_scale,\nthen the compositor may choose a mode that matches either the buffer\nsize or the surface size.  In either case, the surface will fill the\noutput." ] pub fn present_surface_for_mode < F > () where F : FnOnce () -> super :: zwp_fullscreen_shell_mode_feedback_v1 :: ZwpFullscreenShellModeFeedbackV1 { } } }

gets formatted as

pub mod zwp_fullscreen_shell_v1 {
    impl ZwpFullscreenShellV1 {
        ///present surface for display at a particular mode
        ///
        ///If the value of wl_output.scale differs from
        /// wl_surface.buffer_scale, then the compositor may choose a
        /// mode that matches either the buffer size or the surface
        /// size.  In either case, the surface will fill the output.pub fn present_surface_for_mode < F > () where F : FnOnce () -> super :: zwp_fullscreen_shell_mode_feedback_v1 :: ZwpFullscreenShellModeFeedbackV1{
        }
    }
}

when run using these rustfmt options:

wrap_comments = true
normalize_doc_attributes = true

As seen, this comments part of the code.

[burrbull]

Looks like this issue not in "normalize_doc_attributes" but in "max_width"
Because using max_width=10 only produces

mod a {
    mod b {
        #[doc = "test"]        fn foo() -> (){
        }
    }
}

instead of to add newline
I think it works incorrect with any attribute:

mod a {
    #[myattr]fn foo() -> () { }
}

with max_width=7 produces

mod a {
    #[myattr]
    fn foo(
    ) -> (
    )
    {
    }
}

But with max_width=6:

mod a {
    #[myattr]    fn foo() -> (){
    }
}

[burrbull]

Without attributes
Input:

mod a {
    fn foo() -> () { }
}

Output with with max_width=10:

mod a {
    fn foo(
    ) -> ()
    {
    }
}

Output with with max_width=7:

mod a {
    fn foo(
    ) -> (
    )
    {
    }
}

Output with with max_width=6 and less:

mod a {
    fn foo() -> (){
    }
}

6 can be calculated as 4 (result indent of first line) + 2

[ytmimi]

confirming this is still reproducible with rustfmt 1.5.1-nightly (a451a39d 2022-07-25)

[ahl]

I hit this today as well:

input:

impl Client {
    #[doc = "comment"]    pub async fn key_changes_survey_response_education_organization_target_associations < 'a > (& 'a self , limit : Option < i64 > , max_change_version : Option < i64 > , min_change_version : Option < i64 > , offset : Option < i32 > , total_count : Option < bool > , snapshot_identifier : Option < & 'a str >) -> Result < ResponseValue < Vec < types :: TrackedChangesEdFiSurveyResponseEducationOrganizationTargetAssociationKeyChange > > , Error < () > , >{
        todo!()
    }
}

output:

impl Client {
    ///comment    pub async fn key_changes_survey_response_education_organization_target_associations < 'a > (& 'a self , limit : Option < i64 > , max_change_version : Option < i64 > , min_change_version : Option < i64 > , offset : Option < i32 > , total_count : Option < bool > , snapshot_identifier : Option < & 'a str >) -> Result < ResponseValue < Vec < types :: TrackedChangesEdFiSurveyResponseEducationOrganizationTargetAssociationKeyChange > > , Error < () > , >{
        todo!()
    }
}