latexmain specifier does not work unless the mainfile includes the current file?

[user202729]

Description

When I try to use .latexmain file as mentioned in "File .latexmain specifier" section of the documentation,

• if the corresponding mainfile.tex includes the current file, that file is correctly detected.
• otherwise, it will not be detected.

This is according to the behavior in the source code:

vimtex/autoload/vimtex/state.vim

Line 359 in a630f0f

if s:file_reaches_current(l:cand)

The corresponding documentation:

vimtex/doc/vimtex.txt

Line 431 in a630f0f

File .latexmain specifier ~

I think this is mostly a documentation bug (nevertheless, would it be preferable to edit the source code instead to use that file as main regardless?)

[lervag]

If the file is not included, then how can we claim that the specified mainfile is really a main file? I find the current behaviour to make a lot of sense, so if anything, I would prefer to update the docs.

[user202729]

Also fine by me. (it may also be preferable to send a warning message inform the user that latexmain configuration is ignored.)

[lervag]

I believe I answered hastily. The .latexmain has a special behaviour in that it is used as a fallback. I.e., consider this:

touch test.tex
touch main.tex
touch main.tex.latexmain
nvim test.tex

Doing the above, then :VimtexInfo, yields:

VimTeX project: main
  base: main.tex
  root: /home/lervag/test
  tex: /home/lervag/test/main.tex
  main parser: fallback

Notice that it finds main.tex as the main file even if it does not include test.tex, and that the main parser is specified to be "fallback".

[user202729]

Yes, but if there are two candidate main files main1.tex and main2.tex, main1.tex exists and include the current file, but main2.tex.latexmain exist, then main1.tex will be used without any warning that the latexmain file is ignored.

(Actual use case: the Napkin compiles really slowly, so I use a trick to copy the generated PDF file to a backup after each compilation pass, but I also want the forward/reverse search in vimtex to work and use the "Napkin-backup.pdf" file.)

[lervag]

Yes, but if there are two candidate main files main1.tex and main2.tex, main1.tex exists and include the current file, but main2.tex.latexmain exist, then main1.tex will be used without any warning that the latexmain file is ignored.

Hmm, ok. Perhaps I'll add a warning in this case, then. I agree it can be considered confusing, although I still think the current actual behaviour is correct.