Fix "have same type after erasure" check

Perform the overriding checks after elimByName. I observed some problem with
catsEffect2, where a super accessor method with a `() ?=> T` parameter was compared with a
corresponding super accessor method with a `=> T` parameter. One of these methods was generated
before elimByName, the other after. So comparing them at phase elimRepeated + 1 gave two different
types. The problem is fixed by comparing after elimByName, which means that the type of the second
method is converted to match the first.

Author: odersky

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

@@ -1512,17 +1512,17 @@ class TypeComparer(@constructorOnly initctx: Context) extends ConstraintHandling
             arg2.contains(arg1norm)
           case ExprType(arg2res)
           if ctx.phaseId > elimByNamePhase.id && !ctx.erasedTypes
-               && defn.isByNameFunction(arg1) =>
+               && defn.isByNameFunction(arg1.dealias) =>
             // ElimByName maps `=> T` to `()? => T`, but only in method parameters. It leaves
             // embedded `=> T` arguments alone. This clause needs to compensate for that.
-            isSubArg(arg1.argInfos.head, arg2res)
+            isSubArg(arg1.dealias.argInfos.head, arg2res)
           case _ =>
             arg1 match
               case arg1: TypeBounds =>
                 compareCaptured(arg1, arg2)
               case ExprType(arg1res)
               if ctx.phaseId > elimByNamePhase.id && !ctx.erasedTypes
-                   && defn.isByNameFunction(arg2) =>
+                   && defn.isByNameFunction(arg2.dealias) =>
                  isSubArg(arg1res, arg2.argInfos.head)
               case _ =>
                 (v > 0 || isSubType(arg2, arg1)) &&

compiler/src/dotty/tools/dotc/transform/ElimErasedValueType.scala

@@ -117,7 +117,7 @@ class ElimErasedValueType extends MiniPhase with InfoTransformer { thisPhase =>
       // Do the test at the earliest phase where both symbols existed.
       val phaseId =
         sym1.originDenotation.validFor.firstPhaseId max sym2.originDenotation.validFor.firstPhaseId
-      atPhase(elimRepeatedPhase.next)(checkNoConflict(sym1, sym2, sym1.info))
+      atPhase(elimByNamePhase.next)(checkNoConflict(sym1, sym2, sym1.info))
       opc.next()
     }
   }