Allow to skip priotirization of decls in the TraitBridgesCursor - fixes bridges generated in play-framework

Author: WojciechMazur

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

@@ -50,6 +50,7 @@ class Bridges(root: ClassSymbol, thisPhase: DenotTransformer)(using Context) {
    *  We also ignore non-public methods (see `DottyBackendTests.invocationReceivers` for a test case).
    */
   private class TraitBridgesCursor(using Context) extends BridgesCursor{
+    override protected def prioritizeDeferred: Boolean = false
     // Get full list of parents to deduplicate already defined bridges in the parents
     override lazy val parents: Array[Symbol] =
       root.info.parents.map(_.classSymbol).toArray

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

@@ -49,25 +49,35 @@ object OverridingPairs:
     protected def matches(sym1: Symbol, sym2: Symbol): Boolean =
       sym1.isType || sym1.asSeenFrom(self).matches(sym2.asSeenFrom(self))
 
+    /** Should deffered declarations took precedence over the concreate defintions
+     *  In same cases, eg. trait bridges, cursor might lead to incorrect results
+     *  when overriden and overriding methods would be swapped leading to incorrect behaviour
+     */
+    protected def prioritizeDeferred = true
+
     /** The symbols that can take part in an overriding pair */
-    private val decls = {
+    val decls = {
       val decls = newScope
       // fill `decls` with overriding shadowing overridden */
-      def fillDecls(bcs: List[Symbol], deferred: Boolean): Unit = bcs match {
+      def fillDecls(bcs: List[Symbol], include: Symbol => Boolean): Unit = bcs match {
         case bc :: bcs1 =>
-          fillDecls(bcs1, deferred)
+          fillDecls(bcs1, include)
           var e = bc.info.decls.lastEntry
           while (e != null) {
-            if (e.sym.is(Deferred) == deferred && !exclude(e.sym))
+            if (include(e.sym) && !exclude(e.sym))
               decls.enter(e.sym)
             e = e.prev
           }
         case nil =>
       }
-      // first, deferred (this will need to change if we change lookup rules!
-      fillDecls(base.info.baseClasses, deferred = true)
-      // then, concrete.
-      fillDecls(base.info.baseClasses, deferred = false)
+      val baseClasses = base.info.baseClasses
+      if prioritizeDeferred then
+        // first, deferred (this will need to change if we change lookup rules!
+        fillDecls(baseClasses, _.is(Deferred))
+        // then, concrete.
+        fillDecls(baseClasses, !_.is(Deferred))
+      else
+        fillDecls(baseClasses, _ => true)
       decls
     }
 

tests/run/trait-bridge-signatures.check

@@ -72,3 +72,14 @@ class EmptyCollection {
   - generic: public static <C> PartialFunc<java.lang.Object, C> EmptyCollection.andThen(Func1<scala.runtime.Nothing$, C>)
 }
 
+interface play$WSRequest {
+  public abstract play$WSRequest play$WSRequest.addCookies(scala.collection.immutable.Seq)
+  - generic: public abstract play$WSRequest play$WSRequest.addCookies(scala.collection.immutable.Seq<play$WSCookie>)
+  public default play$StandaloneWSRequest play$StandaloneWSRequest.addCookies(scala.collection.immutable.Seq)
+  - generic: public default play$StandaloneWSRequest play$StandaloneWSRequest.addCookies(scala.collection.immutable.Seq<play$WSCookie>)
+  public abstract play$StandaloneWSRequest play$StandaloneWSRequest.withCookies(scala.collection.immutable.Seq)
+  - generic: public abstract play$StandaloneWSRequest play$StandaloneWSRequest.withCookies(scala.collection.immutable.Seq<play$WSCookie>)
+  public abstract play$WSRequest play$WSRequest.withCookies(scala.collection.immutable.Seq)
+  - generic: public abstract play$WSRequest play$WSRequest.withCookies(scala.collection.immutable.Seq<play$WSCookie>)
+}
+

tests/run/trait-bridge-signatures.scala

@@ -71,6 +71,20 @@ trait Collection[+A] extends PartialFunc[Int, A] {
 }
 case object EmptyCollection extends Collection[Nothing]
 
+object play {
+  trait WSCookie
+  trait StandaloneWSRequest {
+    type Self <: StandaloneWSRequest { type Self = StandaloneWSRequest.this.Self }
+    def withCookies(cookies: WSCookie*): Self
+    def addCookies(cookies: WSCookie*): Self = ???
+  }
+
+  trait WSRequest extends StandaloneWSRequest {
+    override type Self = WSRequest
+    override def addCookies(cookies: WSCookie*): Self
+    override def withCookies(cookie: WSCookie*): Self
+  }
+}
 
 object Test {
   def flagsString(m: java.lang.reflect.Method) = {
@@ -118,5 +132,7 @@ object Test {
     ).foreach(show(_, m => List("head", "tail", "from").contains(m.getName())))
 
     show(Class.forName("EmptyCollection"), _.getName() == "andThen")
+
+    show(classOf[play.WSRequest])
   }
 }