From 2da43052f0f0ff04c500c074ee429a6d713a6a2d Mon Sep 17 00:00:00 2001
From: Martin Odersky <odersky@gmail.com>
Date: Sat, 18 Feb 2017 13:12:26 +0100
Subject: Fix off-by-one error in forward reference checking

---
 .../src/dotty/tools/dotc/reporting/diagnostic/messages.scala     | 2 +-
 compiler/src/dotty/tools/dotc/typer/RefChecks.scala              | 2 +-
 tests/neg/i1992.scala                                            | 9 +++++++++
 3 files changed, 11 insertions(+), 2 deletions(-)
 create mode 100644 tests/neg/i1992.scala

diff --git a/compiler/src/dotty/tools/dotc/reporting/diagnostic/messages.scala b/compiler/src/dotty/tools/dotc/reporting/diagnostic/messages.scala
index 94611e10d..9318ad8c6 100644
--- a/compiler/src/dotty/tools/dotc/reporting/diagnostic/messages.scala
+++ b/compiler/src/dotty/tools/dotc/reporting/diagnostic/messages.scala
@@ -1055,7 +1055,7 @@ object messages {
            |
            |Define `${definition.name}` before it is used,
            |or move the definition of `${value.name}` so it does not appear between
-           |the declartion of `${definition.name}` and its use,
+           |the declaration of `${definition.name}` and its use,
            |or define `${value.name}` as lazy.
            |""".stripMargin
   }
diff --git a/compiler/src/dotty/tools/dotc/typer/RefChecks.scala b/compiler/src/dotty/tools/dotc/typer/RefChecks.scala
index eab91701b..7c573d23c 100644
--- a/compiler/src/dotty/tools/dotc/typer/RefChecks.scala
+++ b/compiler/src/dotty/tools/dotc/typer/RefChecks.scala
@@ -789,7 +789,7 @@ class RefChecks extends MiniPhase { thisTransformer =>
       val sym = tree.symbol
       if (sym.exists && sym.owner.isTerm && !sym.is(Lazy))
         currentLevel.levelAndIndex.get(sym) match {
-          case Some((level, symIdx)) if symIdx < level.maxIndex =>
+          case Some((level, symIdx)) if symIdx <= level.maxIndex =>
             ctx.error(ForwardReferenceExtendsOverDefinition(sym, level.refSym), level.refPos)
           case _ =>
         }
diff --git a/tests/neg/i1992.scala b/tests/neg/i1992.scala
new file mode 100644
index 000000000..818b46771
--- /dev/null
+++ b/tests/neg/i1992.scala
@@ -0,0 +1,9 @@
+object Test {
+  def main(args: Array[String]) = {
+    val x: Int => Unit =
+      y => println(x) // error: `x` is a forward reference
+    implicit val z: String => Unit =
+      y => println(implicitly[String => Unit]) // error: `z` is a forward reference
+  }
+}
+
-- 
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