[deps] Revert fontique dep roxmltree to 0.18.1

[waywardmonkeys]

The update to 0.19.0 broke the masonry tests in the xilem repo on Ubuntu.

[waywardmonkeys]

This reverts #42.

[DJMcNab]

This is a not a very compelling fix. Can you test linebender/xilem#221 from 9a519ba instead, which should have this same tree.

I would much prefer us to just fix this failure, if at all possible. cc @xorgy

[waywardmonkeys]

I bisected the tree by running it in CI outside of the Linebender org (my own fork). The memmap2 update and previous commits are okay. Only this last one that updated roxmltree makes things sad.

It does show that we really need actual tests for things.

[dfrg]

I’m confused as to why updating an xml dependency would break tests. Unfortunately, I probably won’t have time to investigate this today.

[waywardmonkeys]

It was several tests failing with:

---- widget::align::tests::centered stdout ----
thread 'widget::align::tests::centered' panicked at /home/runner/.cargo/git/checkouts/parley-7d89eb78db3c5efe/9e2be05/src/layout/line/greedy.rs:516:37:
range end index 1 out of range for slice of length 0

And that line of code was:

    for (i, run_data) in layout.runs[state.runs.clone()].iter().enumerate() {

My guess is that the fontconfig failed to load and then things went wrong after that.

[dfrg]

At a glance, this might have to do with changes to DTD parsing in roxmltree. Changing the fontconfig backend to use Document::parse_with_options with allow_dtd set to true might fix it. If not, we’ll likely need to consider a different xml library.

[dfrg]

The specific line is here:

parley/fontique/src/backend/fontconfig/config.rs

Line 20 in 9e2be05

let Ok(doc) = roxmltree::Document::parse(&text) else {

[dfrg]

This seems to fix it. See #44 and linebender/xilem#224

[waywardmonkeys]

This isn’t needed now!