Simplify defn.FunctionOf.unapply

Author: nicolasstucki

compiler/src/dotty/tools/dotc/cc/CheckCaptures.scala

@@ -408,10 +408,9 @@ class CheckCaptures extends Recheck, SymTransformer:
  else if meth == defn.Caps_unsafeUnbox then
  mapArgUsing(_.forceBoxStatus(false))
  else if meth == defn.Caps_unsafeBoxFunArg then
- mapArgUsing:
- case defn.FunctionOf(paramtpe :: Nil, restpe, isContextual) =>
- defn.FunctionOf(paramtpe.forceBoxStatus(true) :: Nil, restpe, isContextual)
-
+ mapArgUsing: tp =>
+ val defn.FunctionOf(paramtpe :: Nil, restpe, isContextual) = tp.strippedDealias: @unchecked
+ defn.FunctionOf(paramtpe.forceBoxStatus(true) :: Nil, restpe, isContextual)
  else
  super.recheckApply(tree, pt) match
  case appType @ CapturingType(appType1, refs) =>

compiler/src/dotty/tools/dotc/core/Definitions.scala

@@ -1116,16 +1116,13 @@ class Definitions {
  else
  FunctionType(args.length, isContextual).appliedTo(args ::: resultType :: Nil)
  def unapply(ft: Type)(using Context): Option[(List[Type], Type, Boolean)] = {
- ft.dealias match
+ ft match
  case PolyFunctionOf(mt: MethodType) =>
  Some(mt.paramInfos, mt.resType, mt.isContextualMethod)
- case dft =>
- val tsym = dft.typeSymbol
- if isFunctionSymbol(tsym) && ft.isRef(tsym) then
- val targs = dft.argInfos
- if (targs.isEmpty) None
- else Some(targs.init, targs.last, tsym.name.isContextFunction)
- else None
+ case AppliedType(parent, targs) if targs.nonEmpty && isFunctionNType(ft) =>
+ Some(targs.init, targs.last, ft.typeSymbol.name.isContextFunction)
+ case _ =>
+ None
  }
  }
 

compiler/src/dotty/tools/dotc/typer/Applications.scala

@@ -1990,10 +1990,7 @@ trait Applications extends Compatibility {
  // the arity of that function, otherise -1.
  def paramCount(ref: TermRef) =
  val formals = ref.widen.firstParamTypes
- if formals.length > idx then
- formals(idx) match
- case defn.FunctionOf(args, _, _) => args.length
- case _ => -1
+ if formals.length > idx then defn.functionArity(formals(idx))
  else -1
 
  val numArgs = args.length