Add LambdaType#instantiateParamInfos

This generalizes TypeLambda#instantiateBounds to all LambdaTypes.

Author: smarter

compiler/src/dotty/tools/dotc/ast/tpd.scala

@@ -193,7 +193,7 @@ object tpd extends Trees.Instance[Type] with TypedTreeInfo {
   def polyDefDef(sym: TermSymbol, rhsFn: List[Type] => List[List[Tree]] => Tree)(implicit ctx: Context): DefDef = {
     val (tparams, mtp) = sym.info match {
       case tp: PolyType =>
-        val tparams = ctx.newTypeParams(sym, tp.paramNames, EmptyFlags, tp.instantiateBounds)
+        val tparams = ctx.newTypeParams(sym, tp.paramNames, EmptyFlags, tp.instantiateParamInfos(_))
         (tparams, tp.instantiate(tparams map (_.typeRef)))
       case tp => (Nil, tp)
     }

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

@@ -2664,6 +2664,12 @@ object Types {
       myParamRefs
     }
 
+    /** Like `paramInfos` but substitute parameter references with the given arguments */
+    final def instantiateParamInfos(argTypes: => List[Type])(implicit ctx: Context): List[Type] =
+      if (isParamDependent) paramInfos.mapConserve(_.substParams(this, argTypes))
+      else paramInfos
+
+    /** Like `resultType` but substitute parameter references with the given arguments */
     final def instantiate(argTypes: => List[Type])(implicit ctx: Context): Type =
       if (isResultDependent) resultType.substParams(this, argTypes)
       else resultType
@@ -2998,10 +3004,6 @@ object Types {
     lazy val typeParams: List[LambdaParam] =
       paramNames.indices.toList.map(new LambdaParam(this, _))
 
-    /** Instantiate parameter bounds by substituting parameters with given arguments */
-    final def instantiateBounds(argTypes: List[Type])(implicit ctx: Context): List[Type] =
-      paramInfos.mapConserve(_.substParams(this, argTypes))
-
     def derivedLambdaAbstraction(paramNames: List[TypeName], paramInfos: List[TypeBounds], resType: Type)(implicit ctx: Context): Type =
       resType match {
         case resType @ TypeAlias(alias) =>

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

@@ -1120,7 +1120,7 @@ trait Applications extends Compatibility { self: Typer with Dynamic =>
           val tp1Params = tp1.newLikeThis(tp1.paramNames, tp1.paramInfos, defn.AnyType)
           fullyDefinedType(tp1Params, "type parameters of alternative", alt1.symbol.pos)
 
-          val tparams = ctx.newTypeParams(alt1.symbol, tp1.paramNames, EmptyFlags, tp1.instantiateBounds)
+          val tparams = ctx.newTypeParams(alt1.symbol, tp1.paramNames, EmptyFlags, tp1.instantiateParamInfos(_))
           isAsSpecific(alt1, tp1.instantiate(tparams.map(_.typeRef)), alt2, tp2)
         }
       case _ => // (3)