Warn user when importing submodule without the submodules dependencies

[alasdairwilson]

Adds a warning when user imports a submodule without having all the deps defined in that submodules extras.

Closes #7333

In [1]: from sunpy.map import Map
H:\sm2\sunpy\sunpy\util\sysinfo.py:111: ImportWarning: Importing sunpy.map without its extra dependencies may result in errors.
The following packages are not installed:
['matplotlib>=3.5.0']
To install sunpy with these dependencies use `install sunpy[map]`or `install sunpy[all]` for all extras.

[nabobalis]

How do we feel about at least a backport to 5.1?

[dstansby]

Doc build is failing. At a guess it might be because one of the sub-modules you've imported warn_missing_deps into is missing an __all__, so is trying to document warn_missing_deps?

[alasdairwilson]

I made the _warn function private which solves import issues, and should have been done in the first place regardless.

[alasdairwilson]

How do we feel about at least a backport to 5.1?

I don't think it is particularly bugfixxy but I don't really care if you want to backport it.

Tests fixed

[nabobalis]

How do we feel about at least a backport to 5.1?

I don't think it is particularly bugfixxy but I don't really care if you want to backport it.

While its not a bugfix, I feel like its a useful fix that helps anyone who installs sunpy now.

[dstansby]

Suggested change

	f"To install sunpy with these dependencies use `install sunpy[{extras}]`"
	f"To install sunpy with these dependencies use `pip install sunpy[{extras}]` "

[dstansby]

I think having just install sunpy[blah] in the warning is confusing - if something is within backticks I would expect it to be a complete command I can copy/paste. So I think this should be pip install sunpy[...], and there should also be a note that if installed from conda this is a bug that should be reported (because conda install sunpy should install all the extras)

[ayshih]

if installed from conda this is a bug that should be reported

It is potentially a bug; a user could have broken their conda environment.

[nabobalis]

I added a line below this, see if either of you like it.

[alasdairwilson]

Thanks, hadn't gotten round to making changes, I had originally written it this way to avoid the conda/pip issue. But I am happy if it has the extra context about conda.

Should be fixed now.

[lumberbot-app]

Owee, I'm MrMeeseeks, Look at me.

There seem to be a conflict, please backport manually. Here are approximate instructions:

1. Checkout backport branch and update it.

git checkout 5.0
git pull

2. Cherry pick the first parent branch of the this PR on top of the older branch:

git cherry-pick -x -m1 d94d45b08b06b26c732fa5f761251f376e9b940a

3. You will likely have some merge/cherry-pick conflict here, fix them and commit:

git commit -am 'Backport PR #7369: Warn user when importing submodule without the submodules dependencies'

4. Push to a named branch:

git push YOURFORK 5.0:auto-backport-of-pr-7369-on-5.0

5. Create a PR against branch 5.0, I would have named this PR:

"Backport PR #7369 on branch 5.0 (Warn user when importing submodule without the submodules dependencies)"

And apply the correct labels and milestones.

Congratulations — you did some good work! Hopefully your backport PR will be tested by the continuous integration and merged soon!

Remember to remove the Still Needs Manual Backport label once the PR gets merged.

If these instructions are inaccurate, feel free to suggest an improvement.

[lumberbot-app]

Owee, I'm MrMeeseeks, Look at me.

There seem to be a conflict, please backport manually. Here are approximate instructions:

1. Checkout backport branch and update it.

git checkout 5.1
git pull

2. Cherry pick the first parent branch of the this PR on top of the older branch:

git cherry-pick -x -m1 d94d45b08b06b26c732fa5f761251f376e9b940a

3. You will likely have some merge/cherry-pick conflict here, fix them and commit:

git commit -am 'Backport PR #7369: Warn user when importing submodule without the submodules dependencies'

4. Push to a named branch:

git push YOURFORK 5.1:auto-backport-of-pr-7369-on-5.1

5. Create a PR against branch 5.1, I would have named this PR:

"Backport PR #7369 on branch 5.1 (Warn user when importing submodule without the submodules dependencies)"

And apply the correct labels and milestones.

Congratulations — you did some good work! Hopefully your backport PR will be tested by the continuous integration and merged soon!

Remember to remove the Still Needs Manual Backport label once the PR gets merged.

If these instructions are inaccurate, feel free to suggest an improvement.

[Cadair]

For what it's worth, I don't think this PR should have been backported. It broke the DKIST CI for a start.