Merge pull request #5816 from adriaanm/userdefined-apply-212

Allow user-defined `[un]apply` in case companion

4 files changed, 149 insertions, 0 deletions

diff --git a/test/files/neg/userdefined_apply.check b/test/files/neg/userdefined_apply.check
new file mode 100644
index 0000000000..c8c8976f5f
--- /dev/null
+++ b/test/files/neg/userdefined_apply.check
@@ -0,0 +1,25 @@
+userdefined_apply.scala:3: error: overloaded method apply needs result type
+  private def apply(x: Int) = if (x > 0) new ClashOverloadNoSig(x) else apply("")
+                                                                             ^
+userdefined_apply.scala:14: error: overloaded method apply needs result type
+  private def apply(x: Int) = if (x > 0) ClashRecNoSig(1) else ???
+                                         ^
+userdefined_apply.scala:21: error: overloaded method apply needs result type
+  private def apply(x: Boolean) = if (x) NoClashNoSig(1) else ???
+                                         ^
+userdefined_apply.scala:28: error: overloaded method apply needs result type
+  private def apply(x: Boolean) = if (x) NoClashOverload(1) else apply("")
+                                                        ^
+userdefined_apply.scala:45: error: recursive method apply needs result type
+case class NoClashNoSigPoly private(x: Int)
+           ^
+userdefined_apply.scala:39: error: NoClashNoSigPoly.type does not take parameters
+  def apply(x: T) = if (???) NoClashNoSigPoly(1) else ???
+                                             ^
+userdefined_apply.scala:57: error: recursive method apply needs result type
+case class ClashNoSigPoly private(x: Int)
+           ^
+userdefined_apply.scala:51: error: ClashNoSigPoly.type does not take parameters
+  def apply(x: T) = if (???) ClashNoSigPoly(1) else ???
+                                           ^
+8 errors found
diff --git a/test/files/neg/userdefined_apply.scala b/test/files/neg/userdefined_apply.scala
new file mode 100644
index 0000000000..0a0d960b39
--- /dev/null
+++ b/test/files/neg/userdefined_apply.scala
@@ -0,0 +1,57 @@
+object ClashOverloadNoSig {
+  // error: overloaded method apply needs result type
+  private def apply(x: Int) = if (x > 0) new ClashOverloadNoSig(x) else apply("")
+
+  def apply(x: String): ClashOverloadNoSig = ???
+}
+
+case class ClashOverloadNoSig private(x: Int)
+
+object ClashRecNoSig {
+  // TODO: status quo is that the error refers to an overloaded method, which is actually recursive
+  // (we should have unlinked the symbol in the `if(suppress)` part of `applyUnapplyMethodCompleter`)
+  // error: recursive method apply needs result type
+  private def apply(x: Int) = if (x > 0) ClashRecNoSig(1) else ???
+}
+
+case class ClashRecNoSig private(x: Int)
+
+object NoClashNoSig {
+  // error: overloaded method apply needs result type
+  private def apply(x: Boolean) = if (x) NoClashNoSig(1) else ???
+}
+
+case class NoClashNoSig private(x: Int)
+
+object NoClashOverload {
+  // error: overloaded method apply needs result type
+  private def apply(x: Boolean) = if (x) NoClashOverload(1) else apply("")
+
+  def apply(x: String): NoClashOverload = ???
+}
+
+case class NoClashOverload private(x: Int)
+
+
+class BaseNCNSP[T] {
+  // TODO: suppress the following error
+  // error: NoClashNoSigPoly.type does not take parameters
+  def apply(x: T) = if (???) NoClashNoSigPoly(1) else ???
+}
+
+object NoClashNoSigPoly extends BaseNCNSP[Boolean]
+// TODO: position error at definition of apply in superclass instead of on case clss
+// error: recursive method apply needs result type
+case class NoClashNoSigPoly private(x: Int)
+
+
+class BaseCNSP[T] {
+  // TODO: suppress the following error
+  // error: ClashNoSigPoly.type does not take parameters
+  def apply(x: T) = if (???) ClashNoSigPoly(1) else ???
+}
+
+object ClashNoSigPoly extends BaseCNSP[Int]
+// TODO: position error at definition of apply in superclass instead of on case clss
+// error: recursive method apply needs result type
+case class ClashNoSigPoly private(x: Int)
diff --git a/test/files/pos/userdefined_apply.scala b/test/files/pos/userdefined_apply.scala
new file mode 100644
index 0000000000..e29f9f5141
--- /dev/null
+++ b/test/files/pos/userdefined_apply.scala
@@ -0,0 +1,54 @@
+// NOTE: the companion inherits a public apply method from Function1!
+case class NeedsCompanion private (x: Int)
+
+object ClashNoSig { // ok
+  private def apply(x: Int) = if (x > 0) new ClashNoSig(x) else ???
+}
+case class ClashNoSig private (x: Int)
+
+
+object Clash {
+  private def apply(x: Int) = if (x > 0) new Clash(x) else ???
+}
+case class Clash private (x: Int)
+
+object ClashSig {
+  private def apply(x: Int): ClashSig = if (x > 0) new ClashSig(x) else ???
+}
+case class ClashSig private (x: Int)
+
+object ClashOverload {
+  private def apply(x: Int): ClashOverload = if (x > 0) new ClashOverload(x) else apply("")
+  def apply(x: String): ClashOverload = ???
+}
+case class ClashOverload private (x: Int)
+
+object NoClashSig {
+  private def apply(x: Boolean): NoClashSig = if (x) NoClashSig(1) else ???
+}
+case class NoClashSig private (x: Int)
+
+object NoClashOverload {
+  // needs full sig
+  private def apply(x: Boolean): NoClashOverload = if (x) NoClashOverload(1) else apply("")
+  def apply(x: String): NoClashOverload = ???
+}
+case class NoClashOverload private (x: Int)
+
+
+
+class BaseNCP[T] {
+  // error: overloaded method apply needs result type
+  def apply(x: T): NoClashPoly = if (???) NoClashPoly(1) else ???
+}
+
+object NoClashPoly extends BaseNCP[Boolean]
+case class NoClashPoly private(x: Int)
+
+
+class BaseCP[T] {
+  // error: overloaded method apply needs result type
+  def apply(x: T): ClashPoly = if (???) ClashPoly(1) else ???
+}
+object ClashPoly extends BaseCP[Int]
+case class ClashPoly private(x: Int)
diff --git a/test/files/pos/userdefined_apply_poly_overload.scala b/test/files/pos/userdefined_apply_poly_overload.scala
new file mode 100644
index 0000000000..6760c1424f
--- /dev/null
+++ b/test/files/pos/userdefined_apply_poly_overload.scala
@@ -0,0 +1,13 @@
+object Foo {
+  // spurious error if:
+  //   - this definition precedes that of apply (which is overloaded with the synthetic one derived from the case class)
+  //   - AND `Foo.apply` is explicitly applied to `[A]` (no error if `[A]` is inferred)
+  //
+  def referToPolyOverloadedApply[A]: Foo[A] = Foo.apply[A]("bla")
+  //                                                   ^
+  //  found   : String("bla")
+  //  required: Int
+
+  def apply[A](x: Int): Foo[A] = ???
+}
+case class Foo[A](x: String) // must be polymorphic