MatchError on PolyType regression in 2.3.0

[joroKr21]

See for an example: typelevel/cats-tagless#319

Sample stack trace:

error: index.md:168 (mdoc generated code) exception during macro expansion: 
scala.MatchError: [+A]Vector[A] (of class scala.reflect.internal.Types$PolyType)
	at pprint.TPrintLowPri$.typePrintImplRec0(TPrintImpl.scala:151)
	at pprint.TPrintLowPri$.typePrintImplRec(TPrintImpl.scala:32)
	at pprint.TPrintLowPri$.$anonfun$typePrintImplRec0$7(TPrintImpl.scala:103)
	at scala.collection.immutable.List.map(List.scala:246)
	at pprint.TPrintLowPri$.added$2(TPrintImpl.scala:103)
	at pprint.TPrintLowPri$.printArgs$1(TPrintImpl.scala:106)
	at pprint.TPrintLowPri$.typePrintImplRec0(TPrintImpl.scala:200)
	at pprint.TPrintLowPri$.typePrintImplRec(TPrintImpl.scala:32)
	at pprint.TPrintLowPri$.typePrintImpl(TPrintImpl.scala:21)
	at sun.reflect.GeneratedMethodAccessor6.invoke(Unknown Source)
	at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
	at java.lang.reflect.Method.invoke(Method.java:498)
	at scala.reflect.macros.runtime.JavaReflectionRuntimes$JavaReflectionResolvers.$anonfun$resolveJavaReflectionRuntime$6(JavaReflectionRuntimes.scala:51)
	at scala.tools.nsc.typechecker.Macros.macroExpandWithRuntime(Macros.scala:770)

val vectorInterpreter = listInterpreter.mapK(λ[List ~> Vector](_.toVector)); $doc.binder(vectorInterpreter, 1, 4, 1, 21)

[joroKr21]

Looks like an issue in pprint? 🤔

[vlovgr]

Ran into the same issue in vlovgr/ciris#558. Issue for pprint seems to be com-lihaoyi/PPrint#76.

[mpilquist]

FYI this impacts FS2 as well, even when I use mdoc:to-string in all cases.

[joroKr21]

This should be fixed in PPrint