Merge pull request #1737 from retronym/ticket/6555

SI-6555 Better parameter name retention

5 files changed, 48 insertions, 3 deletions

diff --git a/src/compiler/scala/tools/nsc/transform/SpecializeTypes.scala b/src/compiler/scala/tools/nsc/transform/SpecializeTypes.scala
index 2f79472cfb..bbab545d9e 100644
--- a/src/compiler/scala/tools/nsc/transform/SpecializeTypes.scala
+++ b/src/compiler/scala/tools/nsc/transform/SpecializeTypes.scala
@@ -965,6 +965,11 @@ abstract class SpecializeTypes extends InfoTransform with TypingTransformers {
         case (NoSymbol, _)     => None
         case (overridden, env) =>
           val om = specializedOverload(clazz, overridden, env)
+          foreachWithIndex(om.paramss) { (params, i) =>
+            foreachWithIndex(params) { (param, j) =>
+              param.name = overriding.paramss(i)(j).name // SI-6555 Retain the parameter names from the subclass.
+            }
+          }
           debuglog("specialized overload %s for %s in %s: %s".format(om, overriding.name.decode, pp(env), om.info))
           typeEnv(om) = env
           addConcreteSpecMethod(overriding)
diff --git a/src/compiler/scala/tools/nsc/transform/UnCurry.scala b/src/compiler/scala/tools/nsc/transform/UnCurry.scala
index 9829fd0e57..838ea7d5a0 100644
--- a/src/compiler/scala/tools/nsc/transform/UnCurry.scala
+++ b/src/compiler/scala/tools/nsc/transform/UnCurry.scala
@@ -251,7 +251,10 @@ abstract class UnCurry extends InfoTransform
 
           val applyMethodDef = {
             val methSym = anonClass.newMethod(nme.apply, fun.pos, FINAL)
-            methSym setInfoAndEnter MethodType(methSym newSyntheticValueParams formals, restpe)
+            val paramSyms = map2(formals, fun.vparams) {
+              (tp, param) => methSym.newSyntheticValueParam(tp, param.name)
+            }
+            methSym setInfoAndEnter MethodType(paramSyms, restpe)
 
             fun.vparams foreach  (_.symbol.owner =  methSym)
             fun.body changeOwner (fun.symbol     -> methSym)
diff --git a/test/files/neg/t6260.check b/test/files/neg/t6260.check
index 2b7f1a8bfb..46e9bd1dfc 100644
--- a/test/files/neg/t6260.check
+++ b/test/files/neg/t6260.check
@@ -1,10 +1,10 @@
-t6260.scala:3: error: bridge generated for member method apply: (x$1: Box[X])Box[Y] in anonymous class $anonfun
+t6260.scala:3: error: bridge generated for member method apply: (bx: Box[X])Box[Y] in anonymous class $anonfun
 which overrides method apply: (v1: T1)R in trait Function1
 clashes with definition of the member itself;
 both have erased type (v1: Object)Object
     ((bx: Box[X]) => new Box(f(bx.x)))(this)
                   ^
-t6260.scala:8: error: bridge generated for member method apply: (x$1: Box[X])Box[Y] in anonymous class $anonfun
+t6260.scala:8: error: bridge generated for member method apply: (bx: Box[X])Box[Y] in anonymous class $anonfun
 which overrides method apply: (v1: T1)R in trait Function1
 clashes with definition of the member itself;
 both have erased type (v1: Object)Object
diff --git a/test/files/run/t6555.check b/test/files/run/t6555.check
new file mode 100644
index 0000000000..04117b7c2f
--- /dev/null
+++ b/test/files/run/t6555.check
@@ -0,0 +1,22 @@
+[[syntax trees at end of                specialize]] // newSource1
+package <empty> {
+  class Foo extends Object {
+    def <init>(): Foo = {
+      Foo.super.<init>();
+      ()
+    };
+    private[this] val f: Int => Int = {
+      @SerialVersionUID(0) final <synthetic> class $anonfun extends scala.runtime.AbstractFunction1$mcII$sp with Serializable {
+        def <init>(): anonymous class $anonfun = {
+          $anonfun.super.<init>();
+          ()
+        };
+        final def apply(param: Int): Int = $anonfun.this.apply$mcII$sp(param);
+        <specialized> def apply$mcII$sp(param: Int): Int = param
+      };
+      (new anonymous class $anonfun(): Int => Int)
+    };
+    <stable> <accessor> def f(): Int => Int = Foo.this.f
+  }
+}
+
diff --git a/test/files/run/t6555.scala b/test/files/run/t6555.scala
new file mode 100644
index 0000000000..b1a6137786
--- /dev/null
+++ b/test/files/run/t6555.scala
@@ -0,0 +1,15 @@
+import scala.tools.partest._
+import java.io.{Console => _, _}
+
+object Test extends DirectTest {
+
+  override def extraSettings: String = "-usejavacp -Xprint:specialize -d " + testOutput.path
+
+  override def code = "class Foo { val f = (param: Int) => param } "
+
+  override def show(): Unit = {
+    Console.withErr(System.out) {
+      compile()
+    }
+  }
+}