Backport "Fix isAliasType" to LTS (#21081)

Backports #20195 to the LTS branch.

PR submitted by the release tooling.
[skip ci]

Author: WojciechMazur

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

@@ -107,7 +107,7 @@ extension (tp: Type)
       case tp @ CapturingType(parent, refs) =>
         val pcs = getBoxed(parent)
         if tp.isBoxed then refs ++ pcs else pcs
-      case tp: TypeRef if tp.symbol.isAbstractType => CaptureSet.empty
+      case tp: TypeRef if tp.symbol.isAbstractOrParamType => CaptureSet.empty
       case tp: TypeProxy => getBoxed(tp.superType)
       case tp: AndType => getBoxed(tp.tp1) ** getBoxed(tp.tp2)
       case tp: OrType => getBoxed(tp.tp1) ++ getBoxed(tp.tp2)

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

@@ -684,11 +684,9 @@ object SymDenotations {
     def isWrappedToplevelDef(using Context): Boolean =
       !isConstructor && owner.isPackageObject
 
-    /** Is this symbol an abstract type? */
-    final def isAbstractType(using Context): Boolean = this.is(DeferredType)
-
     /** Is this symbol an alias type? */
-    final def isAliasType(using Context): Boolean = isAbstractOrAliasType && !this.is(Deferred)
+    final def isAliasType(using Context): Boolean =
+      isAbstractOrAliasType && !isAbstractOrParamType
 
     /** Is this symbol an abstract or alias type? */
     final def isAbstractOrAliasType: Boolean = isType & !isClass

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

@@ -266,7 +266,7 @@ object TypeErasure {
         tp.paramNames, tp.paramNames map (Function.const(TypeBounds.upper(defn.ObjectType))), tp.resultType)
 
     if (defn.isPolymorphicAfterErasure(sym)) eraseParamBounds(sym.info.asInstanceOf[PolyType])
-    else if (sym.isAbstractType) TypeAlias(WildcardType)
+    else if (sym.isAbstractOrParamType) TypeAlias(WildcardType)
     else if sym.is(ConstructorProxy) then NoType
     else if (sym.isConstructor) outer.addParam(sym.owner.asClass, erase(tp)(using preErasureCtx))
     else if (sym.is(Label)) erase.eraseResult(sym.info)(using preErasureCtx)

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

@@ -2571,7 +2571,7 @@ object Types extends TypeUtils {
       symd.maybeOwner.membersNeedAsSeenFrom(prefix) && !symd.is(NonMember)
       || prefix.match
         case prefix: Types.ThisType =>
-          (symd.isAbstractType
+          (symd.isAbstractOrParamType
             || symd.isTerm
                 && !symd.flagsUNSAFE.isOneOf(Module | Final | Param)
                 && !symd.isConstructor

compiler/src/dotty/tools/dotc/sbt/ExtractAPI.scala

@@ -445,7 +445,7 @@ private class ExtractAPICollector(using Context) extends ThunkHolder {
     if (sym.isAliasType)
       api.TypeAlias.of(name, access, modifiers, as.toArray, typeParams, apiType(tpe.bounds.hi))
     else {
-      assert(sym.isAbstractType)
+      assert(sym.isAbstractOrParamType)
       api.TypeDeclaration.of(name, access, modifiers, as.toArray, typeParams, apiType(tpe.bounds.lo), apiType(tpe.bounds.hi))
     }
   }

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

@@ -31,7 +31,7 @@ trait Deriving {
     /** A version of Type#underlyingClassRef that works also for higher-kinded types */
     private def underlyingClassRef(tp: Type): Type = tp match {
       case tp: TypeRef if tp.symbol.isClass => tp
-      case tp: TypeRef if tp.symbol.isAbstractType => NoType
+      case tp: TypeRef if tp.symbol.isAbstractOrParamType => NoType
       case tp: TermRef => NoType
       case tp: TypeProxy => underlyingClassRef(tp.superType)
       case _ => NoType

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

@@ -596,7 +596,7 @@ trait ImplicitRunInfo:
   private def isAnchor(sym: Symbol) =
     sym.isClass && !isExcluded(sym)
     || sym.isOpaqueAlias
-    || sym.is(Deferred, butNot = Param)
+    || sym.is(Deferred)
     || sym.info.isInstanceOf[MatchAlias]
 
   private def computeIScope(rootTp: Type): OfTypeImplicits =

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

@@ -271,7 +271,7 @@ class Namer { typer: Typer =>
                 analyzeRHS(body)
               case _ =>
                 if rhs.isEmpty || flags.is(Opaque) then flags |= Deferred
-            analyzeRHS(tree.rhs)
+            if flags.is(Param) then tree.rhs else analyzeRHS(tree.rhs)
 
         // to complete a constructor, move one context further out -- this
         // is the context enclosing the class. Note that the context in which a

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

@@ -657,7 +657,7 @@ class Synthesizer(typer: Typer)(using @constructorOnly c: Context):
 
     def canManifest(tp: Manifestable, topLevel: Boolean) =
       val sym = tp.typeSymbol
-      !sym.isAbstractType
+      !sym.isAbstractOrParamType
       && hasStableErasure(tp)
       && !(topLevel && defn.isBottomClassAfterErasure(sym))
 

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

@@ -2649,7 +2649,7 @@ class QuotesImpl private (using val ctx: Context) extends Quotes, QuoteUnpickler
         def isAliasType: Boolean = self.denot.isAliasType
         def isAnonymousClass: Boolean = self.denot.isAnonymousClass
         def isAnonymousFunction: Boolean = self.denot.isAnonymousFunction
-        def isAbstractType: Boolean = self.denot.isAbstractType
+        def isAbstractType: Boolean = self.denot.isAbstractOrParamType
         def isClassConstructor: Boolean = self.denot.isClassConstructor
         def isType: Boolean = self.isType
         def isTerm: Boolean = self.isTerm

library/src/scala/quoted/Quotes.scala

@@ -3993,7 +3993,7 @@ trait Quotes { self: runtime.QuoteUnpickler & runtime.QuoteMatching =>
         /** Is this symbol an anonymous function? */
         def isAnonymousFunction: Boolean
 
-        /** Is this symbol an abstract type? */
+        /** Is this symbol an abstract type or a type parameter? */
         def isAbstractType: Boolean
 
         /** Is this the constructor of a class? */

tests/neg/i20079/Lib_1.scala

@@ -0,0 +1,5 @@
+object Foo:
+  def xyz[A, CC[X] <: Iterable[X]](coll: CC[A]): Unit = ()
+
+object Bar:
+  export Foo.xyz

tests/neg/i20079/Test_2.scala

@@ -0,0 +1,6 @@
+object Test:
+  val ints = List(1)
+  Foo.xyz[Int, List](ints)
+  Foo.xyz[Int, scala.collection.View](ints) // error
+  Bar.xyz[Int, List](ints)
+  Bar.xyz[Int, scala.collection.View](ints) // error