Make eq/ne infix operators

Author: odersky

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

@@ -1278,6 +1278,10 @@ class Definitions {
     if (isTupleClass(cls) || cls == UnitClass) parents :+ syntheticParent(tparams) else parents
   }
 
+  /** Is synthesized symbol with alphanumeric name allowed to be used as an infix operator? */
+  def isInfix(sym: Symbol)(implicit ctx: Context): Boolean =
+    (sym eq Object_eq) || (sym eq Object_ne)
+
   // ----- primitive value class machinery ------------------------------------------
 
   /** This class would also be obviated by the implicit function type design */

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

@@ -675,6 +675,7 @@ trait Checking {
       case Ident(name: SimpleName)
       if !name.exists(isOperatorPart) &&
          !app.symbol.hasAnnotation(defn.InfixAnnot) &&
+         !defn.isInfix(app.symbol) &&
          !app.symbol.maybeOwner.is(Scala2x) &&
          !infixOKSinceFollowedBy(tree.right) &&
          ctx.settings.strict.value =>