Switch TypeApplications to exported extensions

Author: som-snytt

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

@@ -17,12 +17,6 @@ object TypeApplications {
 
   type TypeParamInfo = ParamInfo.Of[TypeName]
 
-  /** Assert type is not a TypeBounds instance and return it unchanged */
-  def noBounds(tp: Type): Type = tp match {
-    case tp: TypeBounds => throw new AssertionError("no TypeBounds allowed")
-    case _ => tp
-  }
-
   /** Extractor for
    *
    *    [X1: B1, ..., Xn: Bn] -> C[X1, ..., Xn]
@@ -153,13 +147,9 @@ object TypeApplications {
         mapOver(t)
     }
   }
-}
-
-import TypeApplications.*
-
-/** A decorator that provides methods for modeling type application */
-class TypeApplications(val self: Type) extends AnyVal {
 
+  // Extensions that model type application.
+  extension (self: Type) {
   /** The type parameters of this type are:
    *  For a ClassInfo type, the type parameters of its class.
    *  For a typeref referring to a class, the type parameters of the class.
@@ -554,7 +544,7 @@ class TypeApplications(val self: Type) extends AnyVal {
     case _ => self.dropDependentRefinement.dealias.argInfos
 
   /** Argument types where existential types in arguments are disallowed */
-  def argTypes(using Context): List[Type] = argInfos mapConserve noBounds
+  def argTypes(using Context): List[Type] = argInfos.mapConserve(_.noBounds)
 
   /** Argument types where existential types in arguments are approximated by their lower bound */
   def argTypesLo(using Context): List[Type] = argInfos.mapConserve(_.loBound)
@@ -588,4 +578,10 @@ class TypeApplications(val self: Type) extends AnyVal {
       .orElse(self.baseType(defn.ArrayClass))
       .argInfos.headOption.getOrElse(NoType)
   }
+
+  /** Assert type is not a TypeBounds instance and return it unchanged */
+  def noBounds: self.type =
+    assert(!self.isInstanceOf[TypeBounds], "no TypeBounds allowed")
+    self
+  }
 }

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

@@ -4374,10 +4374,10 @@ object Types extends TypeUtils {
         setVariances(tparams.tail, vs.tail)
 
     override val isDeclaredVarianceLambda = variances.nonEmpty
-    if isDeclaredVarianceLambda then setVariances(typeParams, variances)
+    if isDeclaredVarianceLambda then setVariances(this.typeParams, variances)
 
     def declaredVariances =
-      if isDeclaredVarianceLambda then typeParams.map(_.declaredVariance)
+      if isDeclaredVarianceLambda then this.typeParams.map(_.declaredVariance)
       else Nil
 
     override def computeHash(bs: Binders): Int =
@@ -4390,7 +4390,7 @@ object Types extends TypeUtils {
         paramNames.eqElements(that.paramNames)
         && isDeclaredVarianceLambda == that.isDeclaredVarianceLambda
         && (!isDeclaredVarianceLambda
-            || typeParams.corresponds(that.typeParams)((x, y) =>
+            || this.typeParams.corresponds(that.typeParams)((x, y) =>
                   x.declaredVariance == y.declaredVariance))
         && {
           val bs1 = new SomeBinderPairs(this, that, bs)
@@ -7183,7 +7183,7 @@ object Types extends TypeUtils {
 
   // ----- Helpers and Decorator implicits --------------------------------------
 
-  implicit def decorateTypeApplications(tpe: Type): TypeApplications = new TypeApplications(tpe)
+  export TypeApplications.{EtaExpandIfHK as _, EtaExpansion as _, TypeParamInfo as _, *}
 
   extension (tps1: List[Type]) {
     @tailrec def hashIsStable: Boolean =

compiler/src/scala/quoted/runtime/impl/QuotesImpl.scala

@@ -1897,9 +1897,9 @@ class QuotesImpl private (using val ctx: Context) extends Quotes, QuoteUnpickler
           dotc.core.Symbols.defn.isTupleNType(self)
         def select(sym: Symbol): TypeRepr = self.select(sym)
         def appliedTo(targ: TypeRepr): TypeRepr =
-          dotc.core.Types.decorateTypeApplications(self).appliedTo(targ)
+          dotc.core.Types.appliedTo(self)(targ)
         def appliedTo(targs: List[TypeRepr]): TypeRepr =
-          dotc.core.Types.decorateTypeApplications(self).appliedTo(targs)
+          dotc.core.Types.appliedTo(self)(targs)
         def substituteTypes(from: List[Symbol], to: List[TypeRepr]): TypeRepr =
           self.subst(from, to)