Substitute new parameter symbols into lambda body

Previously, new synthetic parameter symbols were created for the
apply method parameters, but only used in its `MethodType`. The
`ValDef` trees of the function, along with their symbols, were
used directly as the parameter trees of the apply method.

    % cat sandbox/test.scala
    object Test {
      (x: Int) => {
        (y: Int) => ???
      }
    }

    % scalac-hash v2.10.3 -Xprint:typer,uncurry -uniqid ../scala2/sandbox/test.scala  | egrep 'syntax|\bx'
    [info] v2.10.3 => /Users/jason/usr/scala-v2.10.3-0-g88b5d19
    [[syntax trees at end of                     typer]] // test.scala
        ((x#12152: Int#351) => x#12152)#12151
    [[syntax trees at end of                   uncurry]] // test.scala
            final def apply#15952(x#12152: Int#351): Int#351 = x#12152

This approach dates back a long way: c64152bc3. @odersky tells me it
was most likely due to insufficent substitution/cloning machinery
at the time.

    % qbin/scalac -Xprint:typer,uncurry -uniqid ../scala2/sandbox/test.scala  | egrep 'syntax|\bx'
    [[syntax trees at end of                     typer]] // test.scala
        ((x#13685: Int#1760) => x#13685)#13671
    [[syntax trees at end of                   uncurry]] // test.scala
            final def apply#13959(x#13960: Int#1760): Int#1760 = x#13960

To make this work, I had to fix a problem in symbol substition; this
was commited in the previous commit. In the enclosed test, at Uncurry,
the symbol of the nested class `N` had a `ClassInfoType`, which listed
as a parent `M[a.C]`. When we substituted the new method parameter
symbol `a` for the eponymous function parameter symbol, this was not
touched.

4 files changed, 44 insertions, 3 deletions

diff --git a/src/compiler/scala/tools/nsc/transform/UnCurry.scala b/src/compiler/scala/tools/nsc/transform/UnCurry.scala
index d1d4759ea5..a851585442 100644
--- a/src/compiler/scala/tools/nsc/transform/UnCurry.scala
+++ b/src/compiler/scala/tools/nsc/transform/UnCurry.scala
@@ -232,11 +232,11 @@ abstract class UnCurry extends InfoTransform
               }
               methSym setInfoAndEnter MethodType(paramSyms, restpe)
 
-              fun.vparams foreach  (_.symbol.owner =  methSym)
-              fun.body changeOwner (fun.symbol     -> methSym)
+              fun.body changeOwner (fun.symbol -> methSym)
+              fun.body substituteSymbols (fun.vparams.map(_.symbol), paramSyms)
 
               val body    = typedFunPos(fun.body)
-              val methDef = DefDef(methSym, List(fun.vparams), body)
+              val methDef = DefDef(methSym, body)
 
               // Have to repack the type to avoid mismatches when existentials
               // appear in the result - see SI-4869.
diff --git a/test/files/run/delambdafy-dependent-on-param-subst-2.scala b/test/files/run/delambdafy-dependent-on-param-subst-2.scala
new file mode 100644
index 0000000000..7b6fc597e8
--- /dev/null
+++ b/test/files/run/delambdafy-dependent-on-param-subst-2.scala
@@ -0,0 +1,20 @@
+trait M[-X] {
+  def m(x: X): Boolean
+}
+
+class C
+class A { class C }
+
+object Test {
+  def main(args: Array[String]) {
+    val a = new A
+
+    // class O extends M[a.C] { def m(x: a.C) = true }
+    // (new O: M[Null]).m(null) // Okay
+
+    ((a: A) => {
+      class N extends M[a.C] { def m(x: a.C) = true }
+      new N: M[Null]
+    }).apply(a).m(null) // NPE, missing bridge
+  }
+}
diff --git a/test/files/run/delambdafy-dependent-on-param-subst.flags b/test/files/run/delambdafy-dependent-on-param-subst.flags
new file mode 100644
index 0000000000..2b27e19830
--- /dev/null
+++ b/test/files/run/delambdafy-dependent-on-param-subst.flags
@@ -0,0 +1 @@
+-Ydelambdafy:method
\ No newline at end of file
diff --git a/test/files/run/delambdafy-dependent-on-param-subst.scala b/test/files/run/delambdafy-dependent-on-param-subst.scala
new file mode 100644
index 0000000000..7b6fc597e8
--- /dev/null
+++ b/test/files/run/delambdafy-dependent-on-param-subst.scala
@@ -0,0 +1,20 @@
+trait M[-X] {
+  def m(x: X): Boolean
+}
+
+class C
+class A { class C }
+
+object Test {
+  def main(args: Array[String]) {
+    val a = new A
+
+    // class O extends M[a.C] { def m(x: a.C) = true }
+    // (new O: M[Null]).m(null) // Okay
+
+    ((a: A) => {
+      class N extends M[a.C] { def m(x: a.C) = true }
+      new N: M[Null]
+    }).apply(a).m(null) // NPE, missing bridge
+  }
+}