Fixes record accessors incorrect signature (#19386).

We change the proxy method to take in a single argument. This also
exposed a second issue where the overriden methods were not
invalidated correctly in the `Namer`.

Author: yilinwei

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

@@ -854,7 +854,7 @@ object JavaParsers {
 
       val accessors =
         (for (name, (tpt, annots)) <- fieldsByName yield
-          DefDef(name, Nil, tpt, unimplementedExpr)
+          DefDef(name, List(Nil), tpt, unimplementedExpr)
             .withMods(Modifiers(Flags.JavaDefined | Flags.Method | Flags.Synthetic))
         ).toList
 

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

@@ -906,9 +906,9 @@ class Namer { typer: Typer =>
             && (definesMember || inheritsConcreteMember)
           )
           ||
-          // remove synthetic constructor of a java Record if it clashes with a non-synthetic constructor
-          (denot.isConstructor
-            && isJavaRecord(denot.owner)
+          // remove synthetic constructor or method of a java Record if it clashes with a non-synthetic constructor
+          (isJavaRecord(denot.owner)
+            && (denot.isConstructor || definesMember)
             && denot.owner.unforcedDecls.lookupAll(denot.name).exists(c => c != denot.symbol && c.info.matches(denot.info))
           )
         )

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

@@ -2548,10 +2548,10 @@ class Typer(@constructorOnly nestingLevel: Int = 0) extends Namer
     def canBeInvalidated(sym: Symbol): Boolean =
       sym.is(Synthetic)
       && (desugar.isRetractableCaseClassMethodName(sym.name) ||
-        (sym.isConstructor && sym.owner.derivesFrom(defn.JavaRecordClass)))
+        sym.owner.derivesFrom(defn.JavaRecordClass))
 
     if !sym.info.exists then
-      // it's a discarded method (synthetic case class method or synthetic java record constructor), drop it
+      // it's a discarded method (synthetic case class method or synthetic java record constructor or overriden member), drop it
       assert(canBeInvalidated(sym))
       sym.owner.info.decls.openForMutations.unlink(sym)
       return EmptyTree

tests/pos-java16+/i19386/FromScala.scala

@@ -0,0 +1,2 @@
+def test(r: R1): Unit =
+  val i: Int = r.i()

tests/pos-java16+/i19386/R1.java

@@ -0,0 +1 @@
+public record R1(int i) {}