meson: support other tag systems like ctags

[silvio]

This completes a067f9d "Add TAGS target".

Signed-off-by: Silvio Fricke silvio.fricke@gmail.com

[keszybz]

Hm, maybe we should make this unconditional? It's a bit awkward that when e.g. etags is not installed, and one runs ninja TAGS, the error is "unknown target". It'd actually be better to have the command run and fail, e.g. with "bash: etags : command not found...". So maybe change the command to

['env', tag_prog, ...]

without detecting that tag_prog is present? It'd reduce boilerplate and make the whole thing easier to use.

[silvio]

Better now @keszybz?

[keszybz]

Yeah, that's nice, except one small thing: the target should be TAGS tags not etags. I was mimicking automake here, see ftp://prep.ai.mit.edu/old-gnu/Manuals/automake-1.7.2/html_node/automake_102.html#SEC102. (It was "TAGS" before your patch, but it seems that "tags" is the documented target name.)

[silvio]

ping @keszybz

[keszybz]

Ah, I missed the updated. It's best to leave a comment after pushing, because github does not send out notifications about a push.

[silvio]

Thanks @keszybz