[PATCH 3 of 3] [RFC] dispatch: setup color before pager

[Gregory Szorc]

On Tue, Mar 21, 2017 at 6:11 PM, Matt Harbison <mharbison72 at gmail.com>
wrote:

> (+CC: indygreg, since he added this functionality in 4e02418b4236)
>
> On Tue, 21 Mar 2017 17:36:29 -0400, Augie Fackler <raf at durin42.com> wrote:
>
> On Mon, Mar 20, 2017 at 12:53:19AM -0400, Matt Harbison wrote:
>>
>>> # HG changeset patch
>>> # User Matt Harbison <matt_harbison at yahoo.com>
>>> # Date 1489985511 14400
>>> #      Mon Mar 20 00:51:51 2017 -0400
>>> # Node ID 2a323109f8e7ec5548dd506c2cff05f27fa20c1e
>>> # Parent  6e72bb689e57c985b138c580acb4cad8053dc180
>>> [RFC] dispatch: setup color before pager
>>>
>>
>> Oy, these two I just dunno. I'll defer to other Windows experts.
>>
>
> Heh. You have no idea how sad my Sunday was :-/
>
> Just to be clear, these last two can't be taken as-is.  The output on
> Windows without a pager is black text on a green background.
>
> I did a little more playing, and if we don't do something, this will be a
> regression.  In 4.1, both of these commands colorize in MSYS:
>
> [extensions]
> color =
>
> [pager]
> pager = less
>
> $ hg log -l 5 --config extensions.pager= --config color.pagermode=ansi
>
> $ hg log -l 5 --config color.pagermode=ansi
>
>
> Now, neither of them do (both are now paged).  You have to set
> '--pager=no' to get the color back, or add '--config color.mode=ansi'.  But
> the latter breaks the output when disabling pager.  And even if that
> magically worked, that doesn't help with switching between MSYS and
> cmd.exe, which is why I'd love to make 'auto' smarter.  (I'd rather not
> resort to %include hacks).
>

So the whole reason behind 4e02418b4236 (as documented in the commit
message) is that different pagers support different escape sequences. At
the time, I couldn't figure out an elegant way to detect the pager's
capabilities at run time. So, I added a config option that could be defined
in certain environments (like a controlled msys environment where `less`
was installed as the pager such as the one that Mozilla uses to build
Firefox) so that pager+color would "just work" in both cmd.exe and an msys
environment. More info at
https://bugzilla.mozilla.org/show_bug.cgi?id=545432#c59 and below (search
for my name).

Core Mercurial should focus on behavior in a stock cmd.exe environment and
be best-effort - but not broken - for cygwin, msys, etc. This is what
a78888d98606 aimed to achieve. If someone is running a non-cmd.exe
terminal, I think it is up to the packager to enable a reasonable default
(such as Mozilla setting color.pagermode in our MozillaBuild msys
environment).

Also, if you want a new challenge, the Windows console apparently supports
24-bit color (
https://blogs.msdn.microsoft.com/commandline/2016/09/22/24-bit-color-in-the-windows-console/)
and ANSI+VT-100 escape sequences now.
https://github.com/symfony/symfony/pull/18385 and
https://github.com/Microsoft/BashOnWindows/issues/1173 are somewhat
informative. We could likely detect the Windows version and active terminal
to call SetConsoleMode with ENABLE_VIRTUAL_TERMINAL_PROCESSING. Then
pager.color=ansi should "just work" on Windows.


>
> IIRC, the inter-operation between these two extensions was why the ability
> to register an afterload callback was added.  I'll keep looking at this,
> but I suspect we need a color+pager expert more than a Windows expert.


I think that afterload callback was always buggy and should be fixed or
removed :/


>
>
>
>>> With the previous order, color was None for commands invoked with
>>> --pager=yes at
>>> the time the pager was spawned, which meant the switch over to ANSI mode
>>> on
>>> Windows didn't occur.  That left the color.win32print() in 'auto' mode,
>>> which
>>> meant no color in the pager output.  Non Windows platforms are capable of
>>> printing color with this option.
>>>
>>> diff --git a/mercurial/dispatch.py b/mercurial/dispatch.py
>>> --- a/mercurial/dispatch.py
>>> +++ b/mercurial/dispatch.py
>>> @@ -760,6 +760,13 @@
>>>              for ui_ in uis:
>>>                  ui_.setconfig('ui', 'interactive', 'off', '-y')
>>>
>>> +        # setup color handling
>>> +        coloropt = options['color']
>>> +        for ui_ in uis:
>>> +            if coloropt:
>>> +                ui_.setconfig('ui', 'color', coloropt, '--color')
>>> +            color.setup(ui_)
>>> +
>>>          if util.parsebool(options['pager']):
>>>              ui.pager('internal-always-' + cmd)
>>>          elif options['pager'] != 'auto':
>>> @@ -769,13 +776,6 @@
>>>              for ui_ in uis:
>>>                  ui_.insecureconnections = True
>>>
>>> -        # setup color handling
>>> -        coloropt = options['color']
>>> -        for ui_ in uis:
>>> -            if coloropt:
>>> -                ui_.setconfig('ui', 'color', coloropt, '--color')
>>> -            color.setup(ui_)
>>> -
>>>          if options['version']:
>>>              return commands.version_(ui)
>>>          if options['help']:
>>> _______________________________________________
>>> Mercurial-devel mailing list
>>> Mercurial-devel at mercurial-scm.org
>>> https://www.mercurial-scm.org/mailman/listinfo/mercurial-devel
>>>
>>
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