Fix #10868: Handle semantic name in Java source code

compiler/src/dotty/tools/dotc/parsing/JavaParsers.scala

@@ -6,7 +6,6 @@ import dotty.tools.dotc.core.Constants.Constant
 import dotty.tools.dotc.core.Flags
 import dotty.tools.dotc.core.Flags.FlagSet
 
-
 import JavaTokens._
 import JavaScanners._
 import Scanners.Offset

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

@@ -596,13 +596,27 @@ class Typer extends Namer
         .withSpan(tree.span)
         .computeNullable()
 
-    def typeSelectOnType(qual: untpd.Tree)(using Context) =
-      typedSelect(untpd.cpy.Select(tree)(qual, tree.name.toTypeName), pt)
+    def javaSelectOnType(qual: Tree)(using Context) =
+      // semantic name conversion for `O$` in java code
+      if !qual.symbol.is(JavaDefined) then
+        val tree2 = untpd.cpy.Select(tree)(qual, tree.name.unmangleClassName)
+        assignType(tree2, qual)
+      else
+        assignType(cpy.Select(tree)(qual, tree.name), qual)
 
     def tryJavaSelectOnType(using Context): Tree = tree.qualifier match {
-      case Select(qual, name) => typeSelectOnType(untpd.Select(qual, name.toTypeName))
-      case Ident(name)        => typeSelectOnType(untpd.Ident(name.toTypeName))
-      case _                  => errorTree(tree, "cannot convert to type selection") // will never be printed due to fallback
+      case sel @ Select(qual, name) =>
+        val qual1 = untpd.cpy.Select(sel)(qual, name.toTypeName)
+        val qual2 = typedType(qual1, WildcardType)
+        javaSelectOnType(qual2)
+
+      case id @ Ident(name) =>
+        val qual1 = untpd.cpy.Ident(id)(name.toTypeName)
+        val qual2 = typedType(qual1, WildcardType)
+        javaSelectOnType(qual2)
+
+      case _ =>
+        errorTree(tree, "cannot convert to type selection") // will never be printed due to fallback
     }
 
     def selectWithFallback(fallBack: Context ?=> Tree) =

tests/pos-java-interop/i10868/J.java

@@ -0,0 +1 @@
+class J { T.O$ o; }

tests/pos-java-interop/i10868/T.scala

@@ -0,0 +1 @@
+trait T { object O }