Adding init-po and update-po targets to the meson build system

Hi,

I am working on adding init-po and update-po targets to the meson
build system and have a a couple of questions. First let me explain my
current thinking.

I think the biggest problem is the nls.mk files. autoconf read these
files to generate *.pot files but meson can't read these nls.mk files
natively. So, my solution is switching to using nls.json files instead
of nls.mk files and having a Perl script so that the autoconf system
can parse these nls.json files and read them as nls.mk files as
before. So the big picture is:

- We will switch nls.mk files with nls.json files.
- autoconf will read these nls.json files with the help of perl script.
- meson will read nls.json files and will use a helper Python script
to generate *.pot files.
- meson will have init-po and update-po targets and also singular
targes like psql-init-po.

Does that sound good?

----------------------------------------

Some additional questions:

1. Can init-po and update-po meson targets regenerate *.pot files on
every run or should these files be tracked and regenerated only when
inputs change?
-- I am asking this because implementing the prior one is simpler.
Latter one requires more complicated changes.

2. How closely must the output from meson and autoconf match?
-- Should meson preserve autoconf’s source-reference paths and
ordering exactly, or are differences acceptable? In particular,
generated sources can produce build-tree relative references through
their #line directives. Should we normalize them?

Do you have anything else in mind?

I CCed Álvaro and Peter since I remember they use / work on these areas.

--
Regards,
Nazir Bilal Yavuz
Microsoft