Compiler sometimes crashes with stack overflow when html! is used inside Render impl

[FinnStokes]

Sometimes, using the html macro inside an impl can cause rustc to crash with a stack overflow. A simplified example that reproduces the crash is

use maud::{html, Markup, Render, DOCTYPE};

pub struct Theme;

impl Render for Theme {
    fn render(&self) -> Markup {
        html! {}
    }
}

pub struct Note;

impl Note {
    pub fn render_html(&self) -> Markup {
        html! {
            (DOCTYPE)
        }
    }
}

[FinnStokes]

This seems to be because the html macro inserts extern crate maud, triggering rust-lang/rust#55779. It is very sensitive to the other code around the problem impl. I'm not sure there is anything to be done other than wait for the underlying bug to be fixed, but I thought it would be useful to post here so others running into the same issue would know what was going on.

In my case I am solving it by putting the problem impl inside its own submodule. In the simplified example, this becomes:

use maud::{html, Markup, DOCTYPE};

mod theme {
    use maud::{html, Markup, Render};

    pub struct Theme;

    impl Render for Theme {
        fn render(&self) -> Markup {
            html! {}
        }
    }
}

pub use theme::Theme;

pub struct Note;

impl Note {
    pub fn render_html(&self) -> Markup {
        html! {
            (DOCTYPE)
        }
    }
}

[mbr]

I ran into the same issue, but the suggested workaround at rust-lang/rust#55779 (comment) (adding extern crate maud to the root) fixes it for me.

[kevlarr]

Was wrestling with this for an hour and thought I was crazy. extern crate maud at root was a perfect fix, thanks @mbr

[lambda-fairy]

Looks like this was fixed upstream.

It still reproduces on stable 1.56.0, but works fine on the latest nightly.

$ rustc --version
rustc 1.58.0-nightly (c390d69a6 2021-10-28)

I'll go ahead and close this issue, but leave it pinned for visibility.