Spaces: add new IfMultipleContextBounds label

It considers only context bounds, unlike the earlier ifMultipleBounds
which looks at all bounds.

docs/configuration.md

@@ -4672,6 +4672,12 @@ The parameter also allows the following shortcuts:
 
 ### `spaces.beforeContextBoundColon`
 
+This parameter controls if a space should be used before a colon that precedes
+type context bounds and takes values 'never', 'always', 'ifMultipleBounds', and
+'ifMultipleContextBounds'. The difference between the latter two is: the first
+considers all bounds (including subtype and supertype), whereas the second only
+the context bounds.
+
 ```scala mdoc:defaults
 spaces.beforeContextBoundColon
 ```
@@ -4698,6 +4704,16 @@ spaces.beforeContextBoundColon=IfMultipleBounds
 def method[A: Bound]: B
 def method[A : Bound]: B
 def method[A: Bound: Bound2]: B
+def method[A <: Bound: Bound2]: B
+```
+
+```scala mdoc:scalafmt
+spaces.beforeContextBoundColon=IfMultipleContextBounds
+---
+def method[A: Bound]: B
+def method[A : Bound]: B
+def method[A: Bound: Bound2]: B
+def method[A <: Bound: Bound2]: B
 ```
 
 ### `spaces.inImportCurlyBraces`

scalafmt-core/shared/src/main/scala/org/scalafmt/config/Spaces.scala

@@ -2,6 +2,7 @@ package org.scalafmt.config
 
 import org.scalafmt.util.TokenOps
 
+import scala.meta.Type
 import scala.meta.tokens.{Token => T}
 
 import metaconfig._
@@ -85,17 +86,34 @@ object Spaces {
   implicit lazy val codec: ConfCodecEx[Spaces] = generic.deriveCodecEx(Spaces())
     .noTypos
 
-  sealed abstract class BeforeContextBound
+  sealed abstract class BeforeContextBound {
+    def apply(tb: Type.Bounds): Boolean
+  }
   object BeforeContextBound {
     implicit val codec: ConfCodecEx[BeforeContextBound] = ReaderUtil
-      .oneOfCustom[BeforeContextBound](Always, Never, IfMultipleBounds) {
+      .oneOfCustom[BeforeContextBound](
+        Always,
+        Never,
+        IfMultipleBounds,
+        IfMultipleContextBounds,
+      ) {
         case Conf.Bool(true) => Configured.ok(Always)
         case Conf.Bool(false) => Configured.ok(Never)
       }
 
-    case object Always extends BeforeContextBound
-    case object Never extends BeforeContextBound
-    case object IfMultipleBounds extends BeforeContextBound
+    case object Always extends BeforeContextBound {
+      def apply(tb: Type.Bounds): Boolean = true
+    }
+    case object Never extends BeforeContextBound {
+      def apply(tb: Type.Bounds): Boolean = false
+    }
+    case object IfMultipleBounds extends BeforeContextBound {
+      def apply(tb: Type.Bounds): Boolean =
+        tb.context.length + tb.view.length + tb.lo.size + tb.hi.size > 1
+    }
+    case object IfMultipleContextBounds extends BeforeContextBound {
+      def apply(tb: Type.Bounds): Boolean = tb.context.lengthCompare(1) > 0
+    }
   }
 
   sealed abstract class AfterColonInMatchPattern

scalafmt-core/shared/src/main/scala/org/scalafmt/internal/Router.scala

@@ -6,7 +6,6 @@ import org.scalafmt.config.ImportSelectors
 import org.scalafmt.config.Indents
 import org.scalafmt.config.Newlines
 import org.scalafmt.config.ScalafmtConfig
-import org.scalafmt.config.Spaces
 import org.scalafmt.internal.ExpiresOn.After
 import org.scalafmt.internal.ExpiresOn.Before
 import org.scalafmt.internal.Length.StateColumn
@@ -1762,12 +1761,7 @@ class Router(formatOps: FormatOps) {
        */
 
       case FT(_, _: T.Colon, FT.RightOwner(tp: Type.Bounds)) =>
-        def noNLMod = Space(style.spaces.beforeContextBoundColon match {
-          case Spaces.BeforeContextBound.Always => true
-          case Spaces.BeforeContextBound.IfMultipleBounds => 1 <
-              tp.context.length + tp.view.length + tp.lo.size + tp.hi.size
-          case _ => false
-        })
+        def noNLMod = Space(style.spaces.beforeContextBoundColon(tp))
         getSplitsForTypeBounds(noNLMod, tp, tp.context)
       case FT(_, _: T.Viewbound, FT.RightOwner(tp: Type.Bounds)) =>
         getSplitsForTypeBounds(Space, tp, tp.view)

scalafmt-tests/shared/src/test/resources/spaces/BeforeContextBoundColonIfMultipleBounds.stat

@@ -14,4 +14,26 @@ def myMethod[F[_]: Functor](): Foo
 <<< space before colon with subtype bound #1391
 final class Test[A <: B: ClassTag]
 >>>
-final class Test[A <: B : ClassTag]
+final class Test[A <: B : ClassTag]
+<<< single or multiple context bounds, ifMultipleBounds
+runner.parser = source
+spaces.beforeContextBoundColon = ifMultipleBounds
+===
+final class Test[B: ClassTag]
+final class Test[A <: B: ClassTag]
+final class Test[A <: B: ClassTag: Seq]
+>>>
+final class Test[B: ClassTag]
+final class Test[A <: B : ClassTag]
+final class Test[A <: B : ClassTag : Seq]
+<<< single or multiple context bounds, ifMultipleContextBounds
+runner.parser = source
+spaces.beforeContextBoundColon = ifMultipleContextBounds
+===
+final class Test[B: ClassTag]
+final class Test[A <: B: ClassTag]
+final class Test[A <: B: ClassTag: Seq]
+>>>
+final class Test[B: ClassTag]
+final class Test[A <: B: ClassTag]
+final class Test[A <: B : ClassTag : Seq]

scalafmt-tests/shared/src/test/scala/org/scalafmt/FormatTests.scala

@@ -144,7 +144,7 @@ class FormatTests extends FunSuite with CanRunTests with FormatAssertions {
     val explored = Debug.explored.get()
     logger.debug(s"Total explored: $explored")
     if (!onlyUnit && !onlyManual)
-      assertEquals(explored, 1256164, "total explored")
+      assertEquals(explored, 1256300, "total explored")
     val results = debugResults.result()
     // TODO(olafur) don't block printing out test results.
     // I don't want to deal with scalaz's Tasks :'(