From a4eaa4473376c7b325f3a625cb730cbf9217a706 Mon Sep 17 00:00:00 2001
From: Nicolas Stucki <nicolas.stucki@gmail.com>
Date: Thu, 11 Jan 2018 14:51:47 +0100
Subject: [PATCH 1/2] Fix #2495: Improve error message

---
 .../dotc/reporting/diagnostic/messages.scala     |  9 ++++++---
 compiler/test-resources/repl/errorThenValid      |  5 ++++-
 compiler/test-resources/repl/i2495               | 16 ++++++++++++++++
 3 files changed, 26 insertions(+), 4 deletions(-)
 create mode 100644 compiler/test-resources/repl/i2495

diff --git a/compiler/src/dotty/tools/dotc/reporting/diagnostic/messages.scala b/compiler/src/dotty/tools/dotc/reporting/diagnostic/messages.scala
index 4822be59b57f..1a62b6b1f62d 100644
--- a/compiler/src/dotty/tools/dotc/reporting/diagnostic/messages.scala
+++ b/compiler/src/dotty/tools/dotc/reporting/diagnostic/messages.scala
@@ -189,12 +189,15 @@ object messages {
     val msg = {
       val ofFun =
         if (MethodType.syntheticParamNames(args.length + 1) contains param.name)
-          i" of expanded function $tree"
+          i" of expanded function:\n$tree"
         else
           ""
 
-      i"""missing parameter type for parameter ${param.name}$ofFun, expected = $pt
-         |The argument types of an anonymous function must be fully known. (SLS 8.5)"""
+      i"""missing parameter type
+         |
+         |The argument types of an anonymous function must be fully known. (SLS 8.5)
+         |Expected type: $pt
+         |Missing type for parameter ${param.name}$ofFun"""
     }
 
     val explanation =
diff --git a/compiler/test-resources/repl/errorThenValid b/compiler/test-resources/repl/errorThenValid
index 832c3334f9ca..030d06caba39 100644
--- a/compiler/test-resources/repl/errorThenValid
+++ b/compiler/test-resources/repl/errorThenValid
@@ -1,7 +1,10 @@
 scala> val xs = scala.collection.mutable.ListBuffer[Int]
 1 | val xs = scala.collection.mutable.ListBuffer[Int]
   |          ^
-  |missing parameter type for parameter elems, expected = ?
+  |missing parameter type
+  |
   |The argument types of an anonymous function must be fully known. (SLS 8.5)
+  |Expected type: ?
+  |Missing type for parameter elems
 scala> val xs = scala.collection.mutable.ListBuffer[Int]()
 val xs: scala.collection.mutable.ListBuffer[Int] = ListBuffer()
diff --git a/compiler/test-resources/repl/i2495 b/compiler/test-resources/repl/i2495
new file mode 100644
index 000000000000..f4445d8706f6
--- /dev/null
+++ b/compiler/test-resources/repl/i2495
@@ -0,0 +1,16 @@
+scala> object TypeParam { sealed trait F[A]; case object FI extends F[Int]; case object FS extends F[String]; trait FFn { def apply[A](f: F[A]): A }; val test4: FFn = { case FI => 1; case FS => "" } }
+1 | object TypeParam { sealed trait F[A]; case object FI extends F[Int]; case object FS extends F[String]; trait FFn { def apply[A](f: F[A]): A }; val test4: FFn = { case FI => 1; case FS => "" } }
+  |                                                                                                                                                                   ^
+  |missing parameter type
+  |
+  |The argument types of an anonymous function must be fully known. (SLS 8.5)
+  |Expected type: TypeParam.FFn
+  |Missing type for parameter x$1 of expanded function:
+  |x$1 =>
+  |  x$1 match
+  |    {
+  |      case FI =>
+  |        1
+  |      case FS =>
+  |        ""
+  |    }

From a51091bd1c01525e79d64e544abc6004015e5e96 Mon Sep 17 00:00:00 2001
From: Nicolas Stucki <nicolas.stucki@gmail.com>
Date: Thu, 11 Jan 2018 17:12:30 +0100
Subject: [PATCH 2/2] Remove scripted test

---
 compiler/test-resources/repl/i2495 | 16 ----------------
 1 file changed, 16 deletions(-)
 delete mode 100644 compiler/test-resources/repl/i2495

diff --git a/compiler/test-resources/repl/i2495 b/compiler/test-resources/repl/i2495
deleted file mode 100644
index f4445d8706f6..000000000000
--- a/compiler/test-resources/repl/i2495
+++ /dev/null
@@ -1,16 +0,0 @@
-scala> object TypeParam { sealed trait F[A]; case object FI extends F[Int]; case object FS extends F[String]; trait FFn { def apply[A](f: F[A]): A }; val test4: FFn = { case FI => 1; case FS => "" } }
-1 | object TypeParam { sealed trait F[A]; case object FI extends F[Int]; case object FS extends F[String]; trait FFn { def apply[A](f: F[A]): A }; val test4: FFn = { case FI => 1; case FS => "" } }
-  |                                                                                                                                                                   ^
-  |missing parameter type
-  |
-  |The argument types of an anonymous function must be fully known. (SLS 8.5)
-  |Expected type: TypeParam.FFn
-  |Missing type for parameter x$1 of expanded function:
-  |x$1 =>
-  |  x$1 match
-  |    {
-  |      case FI =>
-  |        1
-  |      case FS =>
-  |        ""
-  |    }