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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: c64152b. @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.
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1 parent cb37548 commit 736613ea8a2fb3eede9bc01346a743c70b44eeaa @retronym retronym committed Nov 23, 2013
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6 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.
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20 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
+ }
+}
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1 test/files/run/delambdafy-dependent-on-param-subst.flags
@@ -0,0 +1 @@
+-Ydelambdafy:method
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20 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
+ }
+}

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