Duplicate entries in tags file (one with absolute path, one with relative path)

[mgedmin]

Describe the bug

I've noticed duplicate tags in files I've edited. They look like this:

  # pri kind tag                          file
  1 F   f    createReportCompetencyModel  /home/mg/src/ivija/src/ivija/threesixty/scoringmodel.py
               def createReportCompetencyModel(threesixty):
  2 F   f    createReportCompetencyModel  src/ivija/threesixty/scoringmodel.py
               def createReportCompetencyModel(threesixty):

Steps to reproduce

1. Generate a tags file externally -- here I used z3c.recipe.tag, which is a horribly complicated solution that ends up invoking exuberant ctags and passing a bunch of absolute directory names to it
2. Edit a file
3. :tsel any name in the file you've edited

Share your setup

• What OS and version of Vim are you using? Ubuntu 18.10, Vim 8.1.1017
• What version of ctags, gtags, or whatever do you have installed? Exuberant Ctags 5.9~svn20110310 from Ubuntu repos
• Are you using g:gutentags_cache_dir? No

Post the logs

I would like to skip this step at this point, if you don't mind, because it seems clear what is happening: the tags file contains absolute filenames, but gutentags assumes it will contain relative ones, according to https://github.com/ludovicchabant/vim-gutentags/issues/70#issuecomment-233926795.

Proposal

I have an idea: why not remove all old entries for a file irrespective of whether it used an absolute or a relative filename? Specifically, in plat/unix/update_tags.sh where currently you do

    cmd="grep --text -Ev '^[^$tab]+$tab$UPDATED_SOURCE$tab' '$TAGS_FILE' > '$TAGS_FILE.temp'"

how about matching both relative and absolute path versions of $UPDATED_SOURCE? This can be painful to compute in portable shell, so maybe compute it in vimscript and pass it as an extra option (-a file=, for alternate path)?

That should remove the possibility of mixups without having to rely on guessing about which style is being used in a project. What do you think?

I think I can create a PR implementing this.

[ludovicchabant]

Hi! I'd rather someone changed z3c.recipe.tag to generate relative paths, since they're a lot nicer to work with than absolute paths... absolute paths get truncated when using Vim in a smaller window or screen. Do you have a good reason to prefer absolute paths? In which case, another option would be to change Gutentags to optionally generate absolute filenames instead.

[mgedmin]

To be honest, the idea didn't occur to me. In fact I would prefer relative paths -- and hey, apparently z3c.recipe.tag has a --tag-relative command-line option.

(I still think it would be nice if vim-gutentags could deal with all sorts of tags out of the box, without the users having to research why duplicate tags appear, and how to convince their tag-generating tools to behave differently. Solving the problem for everyone vs solving it for myself kind of thing. I'm rambling, sorry, I'll stop now.)