$$ equation reference is not identified unless preceded by a blank line

[tillahoffmann]

What version of myst-parser are you using?

2.0.0

What version dependencies are you using?

pydata-sphinx-theme==0.15.2
sphinx-book-theme==1.1.2
sphinxcontrib-applehelp==1.0.8
sphinxcontrib-devhelp==1.0.6
sphinxcontrib-htmlhelp==2.0.5
sphinxcontrib-jsmath==1.0.1
sphinxcontrib-qthelp==1.0.7
sphinxcontrib-serializinghtml==1.1.10
docutils==0.20.1

What operating system are you using?

Mac

Describe the Bug

Equation labels in dollar math are not identified unless the equation is preceded by a blank line. For example, the following two versions work as expected.

First.

$$
a = b + c
$$ (my-eqn)

{eq}`my-eqn`

First.

$$
a = b + c
$$ (my-eqn)
{eq}`my-eqn`

But this version fails with a missing reference.

First.
$$
a = b + c
$$ (my-eqn)

{eq}`my-eqn`

My conf.py contains

myst_enable_extensions = [
    "dollarmath",
]
myst_dmath_double_inline = True
myst_dmath_allow_labels = True

Expected Behavior

Equation labels are identified even if no blank line precedes the equation.

To Reproduce

See above.

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[72757373656c6c]

This is an interesting Issue. The use of spaces, number of spaces, and blank lines is one aspect of MyST-Parser that I'm trying to understand better and be consistent.

From reading the MyST-Parser documentation on Paragraphs , it says,

---

Paragraphs are block of text separated by a blank line.

From the above, I would say there's a requirement for a blank line between the paragraph block (First.) and the $$ extension. When there is is no blank line, the MyST-Parser reads everything until a blank as a paragraph block, thus my-eqn is not defined, resulting in the missing reference.

[i2000s]

Well, an equation is not a paragraph. We commonly say ", where A is something, and B is something". So, if I put a blank line after the equation, will the incident of "where A is something, and B is something" look strange?
Meanwhile, if I missed a blank line after an equation segment, the next time I use a pair of dollar signs to include an inline equation will not be compiled properly.

I suggest we implement a parser to allow equation environment put inside of a pair of double-dollar to put closely in a paragram with other text content.