markdown: Underline incorrectly recognized as italic

[njzjz]

Prettier 3.2.5
Playground link

--parser markdown

Input:

- style\_name = *dplr*
- style\_name = _dplr_
- style_name = _dplr_

Output:

- style_name = _dplr_
- style_name = _dplr_
- style*name = \_dplr*

Expected output:

- style_name = _dplr_
- style_name = _dplr_
- style_name = _dplr_

Why?

Please see how GitHub renders them:

- style\_name = *dplr*

• style_name = dplr

- style\_name = _dplr_

• style_name = dplr

- style_name = _dplr_

• style_name = dplr

- style*name = \_dplr*

• stylename = _dplr

The first three are equivalent, but the last one is wrong. However, when running prettier multiple times, all first three will finally convert to the last one.

xref: deepmodeling/deepmd-kit@fe17568

[zhuozhiyongde]

same issue here, it also effect the math format:

$\sum_{j=1}^{p} |\beta_j| $

$\sum_{j=1}^{p} |\beta_j| $

will format as:

$\sum\_{j=1}^{p} |\beta_j| $

$\sum_{j=1}^{p} |\beta_j| $

[VKondakoff]

Same issue:

nng_pub_open --- create _PUB_ socket

will format as:

nng*pub_open --- create \_PUB* socket

[yanapeycheva]

This issue is most probably connected to #15032 and with the pull request 13676

[njzjz]

This issue is most probably connected to #15032 and with the pull request 13676

I tried the playground in #13676, and it can give the correct result.

Input:

- style\_name = *dplr*
- style\_name = _dplr_
- style_name = _dplr_

• style_name = dplr
• style_name = dplr
• style_name = dplr

Output:

- style\_name = _dplr_
- style\_name = _dplr_
- style_name = _dplr_

• style_name = dplr
• style_name = dplr
• style_name = dplr