Recursive Enums with Doc comments hit recursion limit

[DasLixou]

Reprod:

#[derive(Debug, Template)]
pub enum Test {
    /// ```rinja
    /// {% for x in self.0 %}
    /// {{ x }}
    /// {% endfor %}
    /// ```
    #[template(ext = "html", in_doc = true)]
    A(Vec<Test>),
    /// ```rinja
    /// B
    /// ```
    #[template(ext = "html", in_doc = true)]
    B,
}

latest commit on main (c3fac0ca99579dd2ad73f53c231e56a7dd1c0074)

Error:

error: reached the recursion limit while instantiating `filters::escape::_::_::<impl FastWritable for &Test>::write_into::<filters::escape::EscapeWriter<&mut filters::escape::EscapeWriter<..., ...>, ...>>`
   --> /home/lixou/.cargo/git/checkouts/rinja-b4465ea47ea6e29f/c3fac0c/rinja/src/filters/escape.rs:514:17
    |
514 |                 <T>::write_into(self, dest)
    |                 ^^^^^^^^^^^^^^^^^^^^^^^^^^^
    |
note: `filters::escape::_::_::<impl FastWritable for &T>::write_into` defined here
   --> /home/lixou/.cargo/git/checkouts/rinja-b4465ea47ea6e29f/c3fac0c/rinja/src/filters/escape.rs:513:13
    |
513 |             fn write_into<W: fmt::Write + ?Sized>(&self, dest: &mut W) -> crate::Result<()> {
    |             ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
    = note: the full type name has been written to '/home/lixou/spade-lang/spadedoc/target/debug/deps/spadedoc-6d2618e2fa5f617c.long-type.txt'

[Kijewski]

Thank you for opening the issue! That is a known issue: https://rinja.readthedocs.io/en/latest/template_syntax.html#recursive-structures.

Strangely enough, sometimes it seems to work without adding .render(). I guess in some cases FastWritable calls itself in a(n indirect?) recursion. I don't know if we can properly track the problem to give the user a better error message, or better yet: add .render()? automatically.

[DasLixou]

Oh I was searching that, thanks! But what is meant by a custom iterator with a plain loop?

[Kijewski]

But what is meant by a custom iterator with a plain loop?

Actually, I have no idea. :) @GuillaumeGomez?

[GuillaumeGomez]

I have absolutely no idea either. 😅

[DasLixou]

But is there a nicer way without doing allocations? Or is it at least planned?

[Kijewski]

Yea, I'm not happy that is shortcoming exists.

Could you please create an MRE that produces this error? The best way would probably if you would create a new repo that I could clone and experiment with.

[DasLixou]

Isn't the reprod in the issue description already minimal? How could I make that shorter? LUL

[Kijewski]

When I tried your example yesterday it "worked for me", i.e. it does not reproduce the error. Could be that I copied something wrong or into the wrong place. If you tell me, that it actually does not work, i.e. that it produces the error, then I'll try it again.

[DasLixou]

Okay, I'll try to make a repo

[DasLixou]

...
Tried to reprod on windows, now I get this error:

error: expected item, found `..`
 --> C:\Users\lixou\.cargo\git\checkouts\rinja-b4465ea47ea6e29f\c3fac0c\rinja_derive\src\html.rs:1:1
  |
1 | ../../rinja/src/html.rs
  | ^^ expected item
  |
  = note: for a full list of items that can appear in modules, see <https://doc.rust-lang.org/reference/items.html>

error[E0432]: unresolved import `crate::html::write_escaped_str`
  --> C:\Users\lixou\.cargo\git\checkouts\rinja-b4465ea47ea6e29f\c3fac0c\rinja_derive\src\generator.rs:18:5
   |
18 | use crate::html::write_escaped_str;
   |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ no `write_escaped_str` in `html`

For more information about this error, try `rustc --explain E0432`.

repo here: https://github.com/DasLixou/rinja-recursion-reprod

[Kijewski]

Hehe, I like the commit message. :)

I'll have look if I can find a fix. (But possibly not very soon.)