[Console] Add support for NO_COLOR env var

[Seldaek]

Q	A
Branch?	4.4
Bug fix?	no
New feature?	yes
Deprecations?	no
License	MIT
Doc PR

Adds support for https://no-color.org/ - ideally this would be considered a bugfix and added to older releases IMO, but submitting as new feature for now.

cc @johnstevenson

[johnstevenson]

User-level configuration files and per-instance command-line arguments should override $NO_COLOR

I'm no expert here, but if I use --ansi on the command-line I would be expecting to see color output.

[nicolas-grekas]

Oh, can you please add the same to
src/Symfony/Bridge/PhpUnit/DeprecationErrorHandler.php and
src/Symfony/Component/VarDumper/Dumper/CliDumper.php?

[Seldaek]

Good point @johnstevenson - reading more in depth now I also see that this really only applies to color, and not things like backspace characters and other ANSI codes, I am not sure if the intent of the isDecorated is really just about color or about more than that?

I see in a few places like ProgressBar, non-decorated output won't use overwrite. In Composer we also assume non-decorated means no support for ANSI characters at all in some places.

So I am not so sure if it's the best way here, ideally we'd need a new API for color support independently from ANSI support. I don't know if it's best to lose all ANSI when you set NO_COLOR, or if you rather get colors anyway..

[nicolas-grekas]

I think we shouldn't care about --ansi - it already has higher precedence.
Also disabling only colors but no other ansi codes would be way too challenging.
I'm good with the patch as is - it just need to be added the some more files I listed above.

[Seldaek]

Ok updated 👍

[johnstevenson]

I think we shouldn't care about --ansi - it already has higher precedence.

Oops, sorry, I hadn't realized that.

[nicolas-grekas]

Thank you @Seldaek.

[johnstevenson]

It would be great if this could be listed in the "Libraries supporting NO_COLOR" section at https://no-color.org/ (via https://github.com/jcs/no_color)

[nicolas-grekas]

@johnstevenson totally! could you please send a PR?

[johnstevenson]

Hmm!

How does this look?

Software	Description	Version/Date Supported
Symfony	PHP framework and reusable components	4.4

Which actual release will it be in?

[nicolas-grekas]

Looks good!
In 4.4 yes: https://symfony.com/releases/4.4
Date: end of this month.

[stof]

As they want a link to the release notes, maybe we should wait until the 4.4 release to be able to link to the blog post.

[johnstevenson]

I was just about to PR this:

Software	Description	Version/Date Supported
Symfony	PHP framework and reusable components	4.4.0

I can put the release date in the PR description, so they can decide when to merge it. Does this sound okay?

[johnstevenson]

Sorted.