There's a merged pull request on the void-packages repository

crystal: update to 0.31.0.
https://github.com/void-linux/void-packages/pull/14688

Description:
- Compilation was locally tested with both i686 and x86_64
- Package was locally installed on x86_64, `crystal` and `shards` work good
- Issue with multi-threading: it is not possible to compile with the `-Dpreview_mt` flag. Investigating the [issue](https://github.com/crystal-lang/crystal/issues/8213) someone else had on Arch.

**Edit for Crystal developers:** Regarding multi-threading, a patch will be applied to Crystal in order to support new upstream functions from `gc`, instead of Crystal gc's custom ones. Eventually we will not patch boehm in our repositories, therefore it will be necessary to wait for a next `gc` release to be able to use multi-threading with Crystal.

**Edit 2:** In summary, `crystal` can be merged and multi-threading will be enabled in new releases of `crystal` and `gc`. For now, Crystal works well in single-threaded mode, as before.