Wishlist: Flag to verify filter syntax

[VictorEngmarkHexagon]

After writing a small handful of larger jq filters, one thing which would be really useful would be some way to verify that a filter is syntactically valid, without actually running it on any particular JSON input. Ideally in a way which is easily integrated into pre-commit, which would mean

1. not relying on shell features like standard input to pass some valid JSON to run the filter against, and
2. being able to pass multiple .jq files to verify in a single command.

Workarounds:

• I tried running jq --from-file my.jq --null-input, but that resulted in "jq: error (at ): null (null) has no keys".
• jq --from-file my.jq <<< {}, echo '{}' | jq --from-file my.jq and the like work, but rely on standard input.

[itchyny]

Why you have to avoid standard input? You can't use sh -c ...?

[VictorEngmarkHexagon]

Why you have to avoid standard input? You can't use sh -c ...?

AFAIK pre-commit hooks don't run in a shell, so features like stdin are not available (or at least not configurable). sh -c would work, but would be really clunky, not allowing to run jq directly.

[wader]

Ugly workaround that do requires shell could be something like jq -n "empty | $(cat my.jq)". Another alternative could be to use https://github.com/wader/jq-lsp and some kind of CLI LSP client, i've also thought about adding some kind of argument to syntax check and lint a single file.