Consider adding `-Ywarn-macros:after` about sbt-tpolecat HOT 5 CLOSED

Nope, still showing warnings if an implicit is used in a macro.

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Thanks @kubukoz - we had some discussion about this on #13 where we realised there were problems with all of the macro warning options.

If we use -Ywarn-macros:after, the compiler will warn when there are definitions or imports inside the macro that aren't used, which is outside the caller's control unless they can change the macro code.

If we use -Ywarn-macros:before or -Ywarn-macros:none, the compiler will warn when there are definitions outside the macro that are only used in the macro (i.e. the status quo).

There was some discussion on the PR thread here about adding a -Ywarn-macros:either but it seems like that wasn't taken further as I guess the implementation would be difficult.

Therefore we decided not to change anything at that time just to avoid breakage for users. Do you know if anything has changed in the compiler that would allow us to reevaluate this?

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Interestingly it looks like there may be a -Wwarn-macros:both now:

https://github.com/scala/scala/blob/2.13.x/src/compiler/scala/tools/nsc/settings/Warnings.scala#L105

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gonna try it out :D

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I'm going to close this for now since it doesn't seem like there is any permutation of this option that really works for all users at the moment

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