.gitignore TAGS and emacs lock files #8565

TAGS CTAGS GTAGS ID etc. can be generated (and distclean-ed) by the existing Makefiles, they should be ignored by git.

These should be added to your local global ignore, not the repository. See https://help.github.com/articles/ignoring-files/#create-a-global-gitignore

Yes, see for example #8197. Our policy for gitignore files project-wide is that we ignore files produced by the build, not by external tools or IDEs that one may use. Git has more specific options for that to avoid having to do that for every project.

Not .gitignoring emacs specialities in a project which doesn't depend on emacs makes sense to me. However, vi's .*.swp files and backups currently are in .gitignore. Removing them for consistency is probably not worth it. The TAGS ETAGS etc. files can be created by the project's Makefile as it is now, otherwise I wouldn't have bothered in the first place. However, TAGS-support seems to be automatically provided by automake, unlike lcov-support which looked similar and whose artifacts are in .gitignore, but was explicitly added to configure.ac.

Thus, I'll rescind this pull request. Should you change your mind, the changes are trivial to recreate.

What tools create TAGS files?

TAGS (for emacs) is created by etags(1) and tags (for vi) by ctags(1). M-. can be used to jump to a symbol's definition in emacs and vi will jump to the tag of the keyword the cursor is on with the CTRL-] command. The corresponding make targets are tags and ctags.