Multiple labels inside math directives

[tuncbkose]

Is your feature request related to a problem? Please describe.
I'd like to label and refer to individual lines inside math directives.

Describe the solution you'd like
Something like a :labels: option discussed here could work.

Describe alternatives you've considered
I've tried thinking of sufficiently good workarounds, but nothing will work as well as a proper solution in Sphinx.
I'm working on a document where both the HTML and LaTeX outputs matter and I couldn't devise a band-aid solution that works for both. But if one cares only about one of them, for example HTML, one could probably label/tag manually with LaTeX, and refer to them with {math}`\eqref{...}` .

[tuncbkose]

I was looking around to find the relevant part of the code, which seems to be patches.py.

The current behavior is due to the reference targeting the entire math_block. In order to label individual lines, I imagine one needs to break the math_block into pieces.