Fix java typer problems with inner class references and raw types

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

@@ -34,7 +34,10 @@ object ContextOps:
               if (elem.name == name) return elem.sym.denot // return self
             }
             val pre = ctx.owner.thisType
-            if ctx.isJava then javaFindMember(name, pre, required, excluded)
+            if ctx.isJava then
+              // Note: I didn't verify if there exists a code path that would require `lookInCompanion = true`,
+              // it is just to preserve the original behavior.
+              javaFindMember(name, pre, lookInCompanion = true, required, excluded)
             else pre.findMember(name, pre, required, excluded)
           }
           else // we are in the outermost context belonging to a class; self is invisible here. See inClassContext.
@@ -43,7 +46,13 @@ object ContextOps:
           ctx.scope.denotsNamed(name).filterWithFlags(required, excluded).toDenot(NoPrefix)
       }
 
-    final def javaFindMember(name: Name, pre: Type, required: FlagSet = EmptyFlags, excluded: FlagSet = EmptyFlags): Denotation =
+    /** Look in the prefix with Java semantics.
+     * @param lookInCompanion  If true, try in the companion class of a module as a fallback.
+     *                         Note: originally this was used to type Select nodes in Java code,
+     *                         but that is no longer the case.
+     *                         It is preserved in case it is necessary for denotNamed, but this is unverified.
+     */
+    final def javaFindMember(name: Name, pre: Type, lookInCompanion: Boolean, required: FlagSet = EmptyFlags, excluded: FlagSet = EmptyFlags): Denotation =
       assert(ctx.isJava)
       inContext(ctx) {
 
@@ -53,7 +62,7 @@ object ContextOps:
         val directSearch = pre.findMember(name, pre, required, excluded)
 
         // 2. Try to search in companion class if current is an object.
-        def searchCompanionClass = if preSym.is(Flags.Module) then
+        def searchCompanionClass = if lookInCompanion && preSym.is(Flags.Module) then
           preSym.companionClass.thisType.findMember(name, pre, required, excluded)
           else NoDenotation
 

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

@@ -1512,6 +1512,13 @@ object SymDenotations {
     def namedType(using Context): NamedType =
       if (isType) typeRef else termRef
 
+    /** Like typeRef, but the prefix is widened.
+     *
+     *  See tests/neg/i19619/Test.scala
+     */
+    def javaTypeRef(using Context) =
+      TypeRef(maybeOwner.reachablePrefix.widen, symbol)
+
     /** Like typeRef, but objects in the prefix are represented by their singleton type,
      *  this means we output `pre.O.member` rather than `pre.O$.this.member`.
      *

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

@@ -1542,17 +1542,19 @@ class Namer { typer: Typer =>
       end parentType
 
       /** Check parent type tree `parent` for the following well-formedness conditions:
-       *  (1) It must be a class type with a stable prefix (@see checkClassTypeWithStablePrefix)
+       *  (1) It must be a class type with a stable prefix (unless `isJava`) (@see checkClassTypeWithStablePrefix)
        *  (2) If may not derive from itself
        *  (3) The class is not final
        *  (4) If the class is sealed, it is defined in the same compilation unit as the current class
+       *
+       * @param isJava  If true, the parent type is in Java mode, and we do not require a stable prefix
        */
-      def checkedParentType(parent: untpd.Tree): Type = {
+      def checkedParentType(parent: untpd.Tree, isJava: Boolean): Type = {
         val ptype = parentType(parent)(using completerCtx.superCallContext).dealiasKeepAnnots
         if (cls.isRefinementClass) ptype
         else {
           val pt = checkClassType(ptype, parent.srcPos,
-              traitReq = parent ne parents.head, stablePrefixReq = true)
+              traitReq = parent ne parents.head, stablePrefixReq = !isJava)
           if (pt.derivesFrom(cls)) {
             val addendum = parent match {
               case Select(qual: Super, _) if Feature.migrateTo3 =>
@@ -1621,7 +1623,9 @@ class Namer { typer: Typer =>
       val parentTypes = defn.adjustForTuple(cls, cls.typeParams,
         defn.adjustForBoxedUnit(cls,
           addUsingTraits(
-            ensureFirstIsClass(cls, parents.map(checkedParentType(_)))
+            locally:
+              val isJava = ctx.isJava
+              ensureFirstIsClass(cls, parents.map(checkedParentType(_, isJava)))
           )
         )
       )

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

@@ -156,7 +156,10 @@ trait TypeAssigner {
         val pre = maybeSkolemizePrefix(qualType, name)
         val mbr =
           if ctx.isJava then
-            ctx.javaFindMember(name, pre)
+            // don't look in the companion class here if qual is a module,
+            // we use backtracking to instead change the qual to the companion class
+            // if this fails.
+            ctx.javaFindMember(name, pre, lookInCompanion = false)
           else
             qualType.findMember(name, pre)
 

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

@@ -461,6 +461,10 @@ class Typer(@constructorOnly nestingLevel: Int = 0) extends Namer
                 if (isSelfDenot(defDenot)) curOwner.enclosingClass.thisType
                 else if (ctx.isJava && defDenot.symbol.isStatic) {
                   defDenot.symbol.namedType
+                }
+                else if (ctx.isJava && defDenot.symbol.isClass) {
+                  // in a java context a raw identifier to a class should have a widened prefix.
+                  defDenot.symbol.javaTypeRef
                 } else {
                   val effectiveOwner =
                     if (curOwner.isTerm && defDenot.symbol.maybeOwner.isType)
@@ -4271,14 +4275,16 @@ class Typer(@constructorOnly nestingLevel: Int = 0) extends Namer
       val tree1 =
         if ((pt eq AnyTypeConstructorProto) || tp.typeParamSymbols.isEmpty) tree
         else {
-          val tp1 =
-            if (ctx.isJava)
-              // Cook raw type
-              AppliedType(tree.tpe, tp.typeParams.map(Function.const(TypeBounds.empty)))
-            else
-              // Eta-expand higher-kinded type
-              tree.tpe.etaExpand(tp.typeParamSymbols)
-          tree.withType(tp1)
+          if (ctx.isJava)
+            // Cook raw type
+            val typeArgs = tp.typeParams.map(Function.const(TypeBounds.empty))
+            val tree1 = AppliedTypeTree(tree, typeArgs.map(TypeTree(_)))
+            val tp1 = AppliedType(tree.tpe, typeArgs)
+            tree1.withType(tp1)
+          else
+            // Eta-expand higher-kinded type
+            val tp1 = tree.tpe.etaExpand(tp.typeParamSymbols)
+            tree.withType(tp1)
         }
       if (ctx.mode.is(Mode.Pattern) || ctx.mode.isQuotedPattern || tree1.tpe <:< pt) tree1
       else err.typeMismatch(tree1, pt)

sbt-test/pipelining/Yjava-tasty-paths/a/InnerClass.java

@@ -0,0 +1,65 @@
+package a;
+
+public class InnerClass {
+
+  public class Inner<U> {
+    public U innerField;
+
+    public Inner(U innerField) {
+      this.innerField = innerField;
+    }
+
+    public U getInnerField() {
+      return innerField;
+    }
+  }
+
+  public class Outer<U> {
+
+    public class Nested<V> {
+
+      public U outerField;
+      public V innerField;
+
+      public Nested(U outerField, V innerField) {
+        this.outerField = outerField;
+        this.innerField = innerField;
+      }
+
+      public U getOuterField() {
+        return outerField;
+      }
+
+      public V getInnerField() {
+        return innerField;
+      }
+    }
+  }
+
+  public <U> Inner<U> createInner(U innerField) {
+    return new Inner<>(innerField);
+  }
+
+  public <U, V> Outer<U>.Nested<V> createNested(U outerField, V innerField) {
+    Outer<U> outer = new Outer<>();
+    return outer.new Nested<>(outerField, innerField);
+  }
+
+  public static <U> InnerClass.Inner<U> createInnerStatic(U innerField) {
+    InnerClass innerClass = new InnerClass();
+    return innerClass.new Inner<>(innerField);
+  }
+
+  public static <U, V> InnerClass.Outer<U>.Nested<V> createNestedStatic(U outerField, V innerField) {
+    InnerClass innerClass = new InnerClass();
+    InnerClass.Outer<U> outer = innerClass.new Outer<>();
+    return outer.new Nested<>(outerField, innerField);
+  }
+
+  public static <U, V> void consumeNestedStatic(InnerClass.Outer<U>.Nested<V> nested) {
+  }
+
+  public static <U, V> void consumeNestedStatic2(Outer<U>.Nested<V> nested) {
+  }
+
+}

sbt-test/pipelining/Yjava-tasty-paths/a/InnerClassGen.java

@@ -0,0 +1,78 @@
+package a;
+
+public class InnerClassGen<T> {
+
+  public class Inner<U> {
+    public T rootField;
+    public U innerField;
+
+    public Inner(T rootField, U innerField) {
+      this.rootField = rootField;
+      this.innerField = innerField;
+    }
+
+    public T getRootField() {
+      return rootField;
+    }
+
+    public U getInnerField() {
+      return innerField;
+    }
+  }
+
+  public class Outer<U> {
+
+    public class Nested<V> {
+      public T rootField;
+      public U outerField;
+      public V innerField;
+
+      public Nested(T rootField, U outerField, V innerField) {
+        this.rootField = rootField;
+        this.outerField = outerField;
+        this.innerField = innerField;
+      }
+
+      public T getRootField() {
+        return rootField;
+      }
+
+      public U getOuterField() {
+        return outerField;
+      }
+
+      public V getInnerField() {
+        return innerField;
+      }
+    }
+  }
+
+  public static class OuterStatic<U> {
+    public static class NestedStatic<V> {
+    }
+  }
+
+  public <U> Inner<U> createInner(T rootField, U innerField) {
+    return new Inner<>(rootField, innerField);
+  }
+
+  public <U, V> Outer<U>.Nested<V> createNested(T rootField, U outerField, V innerField) {
+    Outer<U> outer = new Outer<>();
+    return outer.new Nested<>(rootField, outerField, innerField);
+  }
+
+  public static <T, U> InnerClassGen<T>.Inner<U> createInnerStatic(T rootField, U innerField) {
+    InnerClassGen<T> innerClassGen = new InnerClassGen<>();
+    return innerClassGen.new Inner<>(rootField, innerField);
+  }
+
+  public static <T, U, V> InnerClassGen<T>.Outer<U>.Nested<V> createNestedStatic(T rootField, U outerField, V innerField) {
+    InnerClassGen<T> innerClassGen = new InnerClassGen<>();
+    InnerClassGen<T>.Outer<U> outer = innerClassGen.new Outer<>();
+    return outer.new Nested<>(rootField, outerField, innerField);
+  }
+
+  public static <T, U, V> void consumeNestedStatic(InnerClassGen<T>.Outer<U>.Nested<V> nested) {
+  }
+
+}

sbt-test/pipelining/Yjava-tasty-paths/a/InnerClassSub.java

@@ -0,0 +1,52 @@
+package a;
+
+public class InnerClassSub extends InnerClass {
+
+  public class InnerSub<U> extends Inner<U> {
+    public InnerSub(U innerField) {
+      super(innerField);
+    }
+  }
+
+  public class OuterSub<U> extends Outer<U> {
+    public OuterSub() {
+      super();
+    }
+  }
+
+  public <U> Inner<U> createInnerSub(U innerField) {
+    return new InnerSub<>(innerField);
+  }
+
+  public <U, V> Outer<U>.Nested<V> createNestedSub(U outerField, V innerField) {
+    OuterSub<U> outer = new OuterSub<>();
+    return outer.new Nested<>(outerField, innerField);
+  }
+
+  public <U> InnerClass.Inner<U> createInnerSub2(U innerField) {
+    return new InnerSub<>(innerField);
+  }
+
+  public <U, V> InnerClass.Outer<U>.Nested<V> createNestedSub2(U outerField, V innerField) {
+    OuterSub<U> outer = new OuterSub<>();
+    return outer.new Nested<>(outerField, innerField);
+  }
+
+  public static <U> InnerClass.Inner<U> createInnerStatic(U innerField) {
+    InnerClassSub innerClass = new InnerClassSub();
+    return innerClass.new Inner<>(innerField);
+  }
+
+  public static <U, V> InnerClass.Outer<U>.Nested<V> createNestedStatic(U outerField, V innerField) {
+    InnerClassSub innerClass = new InnerClassSub();
+    InnerClassSub.Outer<U> outer = innerClass.new Outer<>();
+    return outer.new Nested<>(outerField, innerField);
+  }
+
+  public static <U, V> void consumeNestedStatic(InnerClass.Outer<U>.Nested<V> nested) {
+  }
+
+  public static <U, V> void consumeNestedStatic2(Outer<U>.Nested<V> nested) {
+  }
+
+}

sbt-test/pipelining/Yjava-tasty-paths/a/RawTypes.java

@@ -0,0 +1,16 @@
+package a;
+
+public class RawTypes {
+
+  public class C<T> {
+    public class D<U> {
+    }
+  }
+
+  public static void mii_Raw_Raw(RawTypes.C.D d) {
+  }
+
+  public static void mii_Raw_Raw2(C.D d) {
+  }
+
+}

sbt-test/pipelining/Yjava-tasty-paths/a/package.scala

@@ -0,0 +1,2 @@
+// THIS FILE EXISTS SO THAT `A.java` WILL BE COMPILED BY SCALAC
+package a