#18502 `help backends` should indicate which backends are used by `update-build-files` Issue created by cognifloyd Is your feature request related to a problem? Please describe.

./pants help backends

shows that

pants.backend.build_files.fix.deprecations

and

pants.backend.build_files.fmt.black

are NOT enabled by default. That surprised me because the

update-build-files

goal definitely uses black. Describe the solution you'd like In the

help backends

output:

Enabled backends are marked with `*`. To enable a backend add it to `[GLOBAL].backend_packages`.

Let's add another character, maybe

-

, to show that a backend is conditionally enabled. The

update-build-files

goal will use a formatter backend without regard to the

[GLOBAL].backend_packages

setting. By default, it uses

pants.backend.build_files.fmt.black

and

pants.backend.build_files.fix.deprecations

. The formatter can be switched from

black

to

yapf

or

buildifier

based on the `[update-build-files].formatter` setting. Using

fix.deprecations

backend is controlled by the `[update-build-files].fix_safe_deprecations` setting (either

True

or

False

). So, these goal-specific backends should get a

-

indicator to show that it is enabled, but only for that one special-purpose goal based on different settings. Describe alternatives you've considered Just remove the backends from the output? That would be confusing too, because the backends exist. Also, you can enable the

pants.backend.build_files.fix.deprecations

backend so that it ALSO runs during the

fix

goal, not just during

update-build-files

. Additional context current output

% ./pants help backends

Backends
--------

List with all known backends for Pants.

Enabled backends are marked with `*`. To enable a backend add it to `[GLOBAL].backend_packages`. 

...
[ ] pants.backend.build_files.fix.deprecations                                              [pants]
[ ] pants.backend.build_files.fmt.black                                                     [pants]
[ ] pants.backend.build_files.fmt.buildifier                                                [pants]
[ ] pants.backend.build_files.fmt.yapf                                                      [pants]
...
[*] pants.backend.python                                                                    [pants]
     Support for Python.
     
     See <https://www.pantsbuild.org/docs/python-backend>.
[ ] pants.backend.python.lint.autoflake                                                     [pants]
     Autoformatter for removing unused Python imports.
     
     See <https://github.com/myint/autoflake> for details.
[*] pants.backend.python.lint.bandit                                                        [pants]
     Security linter for Python.
     
     See <https://www.pantsbuild.org/docs/python-linters-and-formatters> and
     <https://bandit.readthedocs.io/en/latest/>.
[*] pants.backend.python.lint.black                                                         [pants]
     Autoformatter for Python.
     
     See <https://www.pantsbuild.org/docs/python-linters-and-formatters> and
     <https://black.readthedocs.io/en/stable/>.
...

proposed output

% ./pants help backends

Backends
--------

List with all known backends for Pants.

Enabled backends are marked with `*`. To enable a backend add it to `[GLOBAL].backend_packages`. 
The `update-build-files` goal uses backends marked with `-` based on `[update-build-files]` settings.

...
[-] pants.backend.build_files.fix.deprecations                                              [pants]
[-] pants.backend.build_files.fmt.black                                                     [pants]
[ ] pants.backend.build_files.fmt.buildifier                                                [pants]
[ ] pants.backend.build_files.fmt.yapf                                                      [pants]
...
[*] pants.backend.python                                                                    [pants]
     Support for Python.
     
     See <https://www.pantsbuild.org/docs/python-backend>.
[ ] pants.backend.python.lint.autoflake                                                     [pants]
     Autoformatter for removing unused Python imports.
     
     See <https://github.com/myint/autoflake> for details.
[*] pants.backend.python.lint.bandit                                                        [pants]
     Security linter for Python.
     
     See <https://www.pantsbuild.org/docs/python-linters-and-formatters> and
     <https://bandit.readthedocs.io/en/latest/>.
[*] pants.backend.python.lint.black                                                         [pants]
     Autoformatter for Python.
     
     See <https://www.pantsbuild.org/docs/python-linters-and-formatters> and
     <https://black.readthedocs.io/en/stable/>.
...

pantsbuild/pants