Deprecate plugin in favor of gz-plugin

[chapulina]

• Closes TODO: Deprecate/Remove Plugin from Garden #349

Summary

• 0e4a0f5: Move plugin headers back to ignition folder because users shouldn't migrate to gz/common/*Plugin*, but migrate to gz/plugin instead.
• 7090764: Use the correct headers
• e0f0e21: Add deprecation warnings

Test it

CI should pass without warnings.

My local cppcheck had some unknownMacro warnings, but that may be due to my version. I'll see what CI says and suppress those warnings as needed.

Checklist

• Signed all commits for DCO
• Added tests
• Added example and/or tutorial
• Updated documentation (as needed)
• Updated migration guide (as needed)
• Consider updating Python bindings (if the library has them)
• codecheck passed (See contributing)
• All tests passed (See test coverage)
• While waiting for a review on your PR, please help review another open pull request to support the maintainers

Note to maintainers: Remember to use Squash-Merge and edit the commit message to match the pull request summary while retaining Signed-off-by messages.

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[codecov]

Codecov Report

Merging #350 (e0f0e21) into main (3aadb66) will not change coverage.
The diff coverage is n/a.

@@           Coverage Diff           @@
##             main     #350   +/-   ##
=======================================
  Coverage   91.66%   91.66%           
=======================================
  Files           1        1           
  Lines          48       48           
=======================================
  Hits           44       44           
  Misses          4        4           

---

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[scpeters]

I would recommend following the commit pattern from #348 in somewhat reverse order so we can more easily follow the steps:

• first commit: remove the include/ignition/common/Plugin.* redirection headers
• second commit: git mv the relevant include/gz headers back to include/ignition (and nothing else)
• third commit: revert header guards and #include statements for the Plugin* files from 070a6c8

[chapulina]

@scpeters , I reorganized the commits as requested.

@methylDragon , it would be nice to get this in before #356

@mjcarroll , this is one that you could review if you're bored 😉

[methylDragon]

This is the first instance in the codebase of using XXX GZ_DEPRECATED(X) =

It might be something related to the ordering of the deprecation attribute?
The macro is supposed to resolve into __attribute__ ((__deprecated__)) in case it helps. It looks correct though... I don't know why windows is throwing a fit.

[methylDragon]

Traced it!

On windows it becomes:

#ifndef GZ_DEPRECATED
/// For ignition-common5-testing developers: Use this macro to indicate that a
/// function or class has been deprecated and should no longer be used. A
/// version should be specified to provide context to the user about when the
/// function became deprecated.
#define GZ_DEPRECATED(version) GZ_DEPRECATED_ALL_VERSIONS
#endif

then in the generated Export.hh detail header

#  define GZ_DEPRECATED_ALL_VERSIONS __declspec(deprecated)
#endif

https://build.osrfoundation.org/job/ign_common-pr-win/ws/ws/build/ignition-common5/include/gz/common/detail/Export.hh

Perhaps something's up with the __declspec()?

From some docs
"The __declspec keyword must prefix the declaration specification."

[methylDragon]

This thread says namespaces can't be __declspec()'ed (I presume it's the same for using declarations (though that's understandably MUCH harder to google for 😅 ))

Should we just selectively invoke the deprecated macro for everything but windows for the two using invocations?

[methylDragon]

👍 on green CI