bat: bat panics on simple Vue file

I finally got around polishing the prototype code, and opened a PR with production ready code for syntect that fixes this whole class of bugs: https://github.com/trishume/syntect/pull/427

(Before this is fixed in bat, syntect needs to release 5.0.0 and bat needs to start depending on that release of course, so it might still take a while before this is fixed for bat end-users)

Thank you for reporting this. That’s unfortunate.

It should be possible to somehow verify that syntaxes do not include broken references when building the binary assets. This might need to be fixed upstream (in syntect).

thread 'main' panicked at 'Can only call resolve on linked references: ByScope { scope: <text.pug>, sub_context: None }', /home/travis/.cargo/registry/src/github.com-1ecc6299db9ec823/syntect-3.3.0/src/parsing/syntax_definition.rs:192:18
note: run with `RUST_BACKTRACE=1` environment variable to display a backtrace

I meet same error with single Vue component file with pug template syntax.

I started work on #1616, and realised the output from syntect wasn’t helpful enough, so I created https://github.com/trishume/syntect/pull/338

Linking to this “version” of syntect, now when building assets in bat, we get:

Some referenced contexts could not be found!
- Syntax 'Vue Component' with scope 'text.html.vue' has unresolved context reference ByScope { scope: <source.sss>, sub_context: None }
- Syntax 'Vue Component' with scope 'text.html.vue' has unresolved context reference ByScope { scope: <text.slm>, sub_context: None }
- Syntax 'Vue Component' with scope 'text.html.vue' has unresolved context reference ByScope { scope: <source.livescript>, sub_context: None }
- Syntax 'Vue Component' with scope 'text.html.vue' has unresolved context reference ByScope { scope: <source.postcss>, sub_context: None }
- Syntax 'Vue Component' with scope 'text.html.vue' has unresolved context reference ByScope { scope: <text.pug>, sub_context: None }
- Syntax 'Vue Component' with scope 'text.html.vue' has unresolved context reference ByScope { scope: <text.jade>, sub_context: None }
- Syntax 'Svelte' with scope 'text.html.svelte' has unresolved context reference ByScope { scope: <source.postcss>, sub_context: None }
- Syntax 'Svelte' with scope 'text.html.svelte' has unresolved context reference ByScope { scope: <source.livescript>, sub_context: None }

Here is a working prototype that should fix this and all other panics in the same family, namely panics caused by attempts to embed syntaxes that are missing: https://github.com/Enselic/bat/pull/52

The proposed solution makes syntect fall back to Plain Text syntax for embedded syntaxes that are missing, which seems to work well. This also seems to be what Sublime Text is doing in cases like these.

The prototype includes a commit that adjust the Vue syntax regression test to also include a snippet of Pug:

<template lang='pug'>
  #container.col
    p This shall be formated as Plain Text as long as a Pug syntax definition is missing
</template>

Current bat crashes in Vue files with the above, but the prototype handles it well (continues to highlight subsequent Vue code as before).

Further progress on this currently blocked mostly by https://github.com/trishume/syntect/pull/382 which the syntect code is based on to reduce future conflicts. But as soon as that is merged I plan on resuming work on this.

If you have any concerns with regards to falling back to Plain Text syntax in cases like these, I would love to hear them!

It should be possible to somehow verify that syntaxes do not include broken references when building the binary assets. This might need to be fixed upstream (in syntect).

I’ve created a PR which will add a new API to syntect for this, but I’m sure it could be improved: https://github.com/trishume/syntect/pull/332

See also https://github.com/sharkdp/bat/issues/1492

Turns out it was necessary to also change style to template. Here is how to reproduce with a one-liner:

% echo "<template lang='pug'>\n</template>" > /tmp/crash.vue && bat /tmp/crash.vue
[...]
thread 'main' panicked at 'Can only call resolve on linked references: ByScope { scope: <text.pug>, sub_context: None }', [...]

Understood, thank you. Removed the milestone (which - anyway - was only a suggestion).

@sharkdp Nope, Vue still has unresolved syntaxes (

- Syntax 'Vue Component' with scope 'text.html.vue' has unresolved context reference ByScope { scope: <source.postcss>, sub_context: None }
- Syntax 'Vue Component' with scope 'text.html.vue' has unresolved context reference ByScope { scope: <source.sss>, sub_context: None }
- Syntax 'Vue Component' with scope 'text.html.vue' has unresolved context reference ByScope { scope: <text.jade>, sub_context: None }
- Syntax 'Vue Component' with scope 'text.html.vue' has unresolved context reference ByScope { scope: <text.pug>, sub_context: None }
- Syntax 'Vue Component' with scope 'text.html.vue' has unresolved context reference ByScope { scope: <text.slm>, sub_context: None }

)

I am still convinced that my proposed approach to solve it “once and for all” (https://github.com/sharkdp/bat/issues/915#issuecomment-950274207) is the right one, but I actually think we should wait with fixing this until after 0.19.0. It is a bit tricky to get the code right in syntect, and trishume seems busy these days, so there is a risk that that work would delay a release several months more in the worst case.

syntect released on Aug 2: https://github.com/trishume/syntect/releases/tag/v4.6.0

A tiny bit of additional code (to print the warnings to the console at asset building time) - I have already made the necessary changes locally, just waiting for a syntect release before I make a PR. Or is it okay to depend on the syntect git repository directly?