On 09.03.2017 08:15, Benjamin Peterson wrote:
> 
> "eo_XX" is just something that appears in the X11 locale.alias file. My change doesn't add that; it was already there. (for Esperanto, which I suppose explains the "XX")

Yes, I know. That was an example of a bug in the X.org list.

> Most of the changes you identify the glibc aliases taking precedence over the X11 ones. e.g., glibc has "fi_FI ISO-8859-1" while the X11 locale list has "fi_FI.ISO8859-15". That seems correct to me as far as the intent of this change is concerned.

No, it's not correct. ISO-8859-1 is the older version of Latin-1
without the Euro sign. ISO8859-15 adds it.

> How do you propose to pick and choose what we use from the X11 locale alias list?

We have to go through the list one by one to check whether
the mapping update makes sense and is correct.

This will be difficult in a few cases where the glibc mapping
switches to UTF-8 from an ISO encoding. We'll have to find
evidence that this change does indeed make sense.

My take on this is that the X.org folks know better than the
glibc folks, since the former have to deal with end users that
rely on the locale settings a lot more than applications
using glibc for getting an initial locale setting right.

Also note that you are parsing the SUPPORTED file from
glibc (in slightly processed form):

https://github.com/bminor/glibc/blob/master/localedata/SUPPORTED

This file does not provide a locale alias mapping as
the routine in makelocalealias.py suggests. Instead it's
a list of locales to install by default:

https://github.com/bminor/glibc/blob/73dfd088936b9237599e4ab737c7ae2ea7d710e1/localedata/Makefile

In glibc you can define both the locale and the encoding separately
when creating a locale using localedef and the file simply provides
the default parameters to pass to this tool.

As such, I don't see how you can derive a default alias
meaning from the file.

It's simply an indication of what glibc would have installed
in case it were installed from source, but that's hardly ever
the case. On today's systems only a bare subset of locales
is installed and more added as necessary, so you rarely have
all the locales defined in SUPPORTED installed on a system.

So the file doesn't even provide a hint at what could
be installed on the system ("locale -a" gives you that list).

Here's the history:

https://github.com/bminor/glibc/commits/master/localedata/SUPPORTED

It's merely a list of additions and removals from the
default set. Nothing more. It does provide a list of
known and supported locales, but no usable or authoritative
encoding information (locales are defined using Unicode, so
the encoding is a parameter and not predefined).

Overall, I believe the file is pretty useless to use as
basis for an alias table providing encoding information.
It may provide some ideas for corrections, but should not
override the X.org one by default.

On the other hand, you have the local.alias master file:

https://cgit.freedesktop.org/xorg/lib/libX11/tree/nls/locale.alias.pre

together with the history of why changes were made and when.
This is an authoritative resource and people are making changes
against it from the user perspective.

I'd suggest to make the override optional in makelocalealias.py
via a command line switch and to use this for manually adding
or fixing X.org entries.

If you absolutely want to parse the glibc file per default as
well, please only let it add new entries, not override existing
ones. As we've seen in the patch, those overrides need to be
carefully reviewed.