Citing references with [@citationname] in name of theorems is now brokwn

[Scinawa]

Dear all,
I think that the last update broke the possibility to insert citations in the name of the theorems.
For example, before this code produced the intended outcome

```{theorem, name="Whatever name, by [@citation]"}
 Bla bla
```

Now the same code outputs a block with name "Whatever name, by [@citation]".

Is this the intended behavior?

Thank you!

[cderv]

The special environment mechanism has changed syntax to Custom Blocks: https://bookdown.org/yihui/bookdown/markdown-extensions-by-bookdown.html#theorems

In version 0.25, the knitr engine syntax has switched to generate this special syntax now: https://github.com/rstudio/bookdown/blob/main/NEWS.md#major-changes

The theorem and proof knitr engines no longer use the block2 knitr engine to create theorem/proof environments, but write out fenced Divs instead, which is the new syntax for these environments. Note that this means these environments are no longer supported in EPUB output (they work only in HTML and PDF), but hopefully the support will be back in the future (thanks, @deleeuw, #1178).

The name argument does not support citation as it only supports raw content now. We'll try to improve that to at least handle Markdown syntax.

However, bookdown has a Text reference feature to help with that:

Try this:

---
title: "Untitled"
output: bookdown::html_document2
bibliography: packages.bib
---

```{r}
knitr::write_bib("knitr", "packages.bib")
```

See [@R-knitr]

(ref:knitr) Whatever name, by [@R-knitr]

:::{.theorem name="(ref:knitr)"}
 Bla bla
:::

Thanks for the report.

[Scinawa]

Thanks for your answer!

I might have to report another bug. The parameter output in the bookdown::fence_theorems() function is not working properly.

The function returns without errors, but it does not produce any file.

Ale.

[cderv]

Oh how do we missed that... Currently, if output is different that NULL it will overwrite the input

This should behave as expected in dev version now. Thanks!