Merge pull request #4822 from retronym/ticket/9178

SI-9178 Don't eta expand to an Function0-like SAM expected type

10 files changed, 55 insertions, 0 deletions

diff --git a/test/files/pos/t9178.flags b/test/files/pos/t9178.flags
new file mode 100644
index 0000000000..7de3c0f3ee
--- /dev/null
+++ b/test/files/pos/t9178.flags
@@ -0,0 +1 @@
+-Xfatal-warnings -deprecation
diff --git a/test/files/pos/t9178.scala b/test/files/pos/t9178.scala
new file mode 100644
index 0000000000..f2cf20a778
--- /dev/null
+++ b/test/files/pos/t9178.scala
@@ -0,0 +1,13 @@
+// eta expansion to Function0 is problematic (as shown here).
+// Perhaps we should we deprecate it? See discussion in the comments of
+// on SI-9178.
+//
+// This test encodes the status quo: no deprecation.
+object Test {
+  def foo(): () => String = () => ""
+  val f: () => Any = foo
+
+  def main(args: Array[String]): Unit = {
+    println(f()) // <function0>
+  }
+}
diff --git a/test/files/pos/t9178b.flags b/test/files/pos/t9178b.flags
new file mode 100644
index 0000000000..48fd867160
--- /dev/null
+++ b/test/files/pos/t9178b.flags
@@ -0,0 +1 @@
+-Xexperimental
diff --git a/test/files/pos/t9178b.scala b/test/files/pos/t9178b.scala
new file mode 100644
index 0000000000..cbeaed4f17
--- /dev/null
+++ b/test/files/pos/t9178b.scala
@@ -0,0 +1,7 @@
+abstract class Test{
+  val writeInput: java.io.OutputStream => Unit
+  def getOutputStream(): java.io.OutputStream
+
+  writeInput(getOutputStream)
+}
+
diff --git a/test/files/run/t9178a.flags b/test/files/run/t9178a.flags
new file mode 100644
index 0000000000..48fd867160
--- /dev/null
+++ b/test/files/run/t9178a.flags
@@ -0,0 +1 @@
+-Xexperimental
diff --git a/test/files/run/t9178a.scala b/test/files/run/t9178a.scala
new file mode 100644
index 0000000000..4788841f8d
--- /dev/null
+++ b/test/files/run/t9178a.scala
@@ -0,0 +1,15 @@
+trait Sam { def apply(): Unit }
+abstract class Test {
+  def foo(): Sam
+  // no parens, instantiateToMethodType would wrap in a `new Sam { def apply = foo }`
+  // rather than applying to an empty param list() */
+  val f: Sam = foo
+}
+
+object Test extends Test {
+  lazy val samIAm = new Sam { def apply() {} }
+  def foo() = samIAm
+  def main(args: Array[String]): Unit = {
+    assert(f eq samIAm, f)
+  }
+}
diff --git a/test/files/run/t9489.flags b/test/files/run/t9489.flags
new file mode 100644
index 0000000000..48fd867160
--- /dev/null
+++ b/test/files/run/t9489.flags
@@ -0,0 +1 @@
+-Xexperimental
diff --git a/test/files/run/t9489/A.java b/test/files/run/t9489/A.java
new file mode 100644
index 0000000000..c3536faa14
--- /dev/null
+++ b/test/files/run/t9489/A.java
@@ -0,0 +1,3 @@
+public class A {
+  public B b() { return null; }
+}
diff --git a/test/files/run/t9489/B.java b/test/files/run/t9489/B.java
new file mode 100644
index 0000000000..e5d1278cd7
--- /dev/null
+++ b/test/files/run/t9489/B.java
@@ -0,0 +1,3 @@
+public abstract class B {
+  public abstract int m();
+}
diff --git a/test/files/run/t9489/test.scala b/test/files/run/t9489/test.scala
new file mode 100644
index 0000000000..1b745af865
--- /dev/null
+++ b/test/files/run/t9489/test.scala
@@ -0,0 +1,10 @@
+class T {
+  def f(a: A) = g(a.b) // was: "found Int, required B"
+  def g(b: => B) = null
+}
+
+object Test extends T {
+  def main(args: Array[String]): Unit = {
+    f(new A)
+  }
+}