combine syntax appears to be behaving unexpectedly when kitchen sink importing

[longcao]

combine and |+| are listed as aliases for one another but when using the kitchen sink imports, they appear to be routing to an unexpected implementation:

import cats.std.all._
import cats.syntax.all._

scala> Option("asdf") combine Option("qwer") 
res0: Option[String] = Some(asdf)

scala> Option("asdf") |+| Option("qwer") 
res1: Option[String] = Some(asdfqwer)

scala> scala.reflect.runtime.universe.reify { Option("asdf") |+| Option("qwer") }
res2: reflect.runtime.universe.Expr[Option[String]] = Expr[scala.Option[java.lang.String]](`package`.all.semigroupSyntax(Option.apply("asdf"))(`package`.all.optionMonoid(`package`.all.stringMonoid)).$bar$plus$bar(Option.apply("qwer")))

scala> scala.reflect.runtime.universe.reify { Option("asdf") combine Option("qwer") }
res3: reflect.runtime.universe.Expr[Option[String]] = Expr[scala.Option[java.lang.String]](`package`.all.toSemigroupKOps(Option.apply("asdf"))(`package`.all.optionInstance).combine(Option.apply("qwer")))

For now, I've decided to work around this by importing a bit more strictly down to what I want:

import cats.std.all._
import cats.syntax.semigroup._

scala> Option("asdf") combine Option("qwer")
res0: Option[String] = Some(asdfqwer)

[ceedubs]

here is a relevant gitter conversation

[ceedubs]

My initial reaction to this is that we should probably rename the combine on SemigroupK to combineK or something to avoid ambiguity. Separately, I think that I think that the Semigroup[Option[A]] instance should be the one derived from SemigroupK[Option] as opposed to the one derived from Semigroup[A]. This has been discussed before, but I can't recall what everyone thought. FWIW I believe this is what Idris does.

[milessabin]

This is going to be an issue for Monoid and MonoidK as well, right?

[milessabin]

And probably Alternative. See also #757.

[ceedubs]

I started putting together a PR for this, but I think that any change for this is going to run into conflicts with #757, so maybe we should hold on this until that one is merged.

[milessabin]

Or incorporate your changes into that?