From 180ab409f9a2c165b7ef7d53f12b95b3076be559 Mon Sep 17 00:00:00 2001
From: Liu Fengyun <liu@fengy.me>
Date: Thu, 21 Mar 2019 10:40:18 +0100
Subject: [PATCH] Add document and test for overload resolution

---
 .../changed-features/overload-resolution.md   | 31 +++++++++++++++++++
 docs/sidebar.yml                              |  2 ++
 tests/pos/i6116.scala                         | 14 +++++++++
 3 files changed, 47 insertions(+)
 create mode 100644 docs/docs/reference/changed-features/overload-resolution.md
 create mode 100644 tests/pos/i6116.scala

diff --git a/docs/docs/reference/changed-features/overload-resolution.md b/docs/docs/reference/changed-features/overload-resolution.md
new file mode 100644
index 000000000000..c96731cdc4b6
--- /dev/null
+++ b/docs/docs/reference/changed-features/overload-resolution.md
@@ -0,0 +1,31 @@
+---
+layout: doc-page
+title: "Changes in Overload Resolution"
+---
+
+Overload resolution in Dotty takes all argument blocks into account instead of
+just the first argument block.
+
+For example, the following code compiles in Dotty, while it results in an
+ambiguous overload error in Scala2:
+
+```Scala
+def f(x: Int)(y: String): Int = 0
+def f(x: Int)(y: Int): Int = 0
+
+f(3)("")     // ok
+```
+
+The following code compiles as well:
+
+```Scala
+def g(x: Int)(y: Int)(z: Int): Int = 0
+def g(x: Int)(y: Int)(z: String): Int = 0
+
+g(2)(3)(4)     // ok
+g(2)(3)("")    // ok
+```
+
+This change is motivated by the new language feature [extension
+methods](../contextual/extension-methods.html), where emerges the need to do
+overload resolution based on additional argument blocks.
diff --git a/docs/sidebar.yml b/docs/sidebar.yml
index aeb8d4e8d935..ca7e91da3f7e 100644
--- a/docs/sidebar.yml
+++ b/docs/sidebar.yml
@@ -99,6 +99,8 @@ sidebar:
               url: docs/reference/changed-features/implicit-resolution.html
             - title: Implicit Conversions
               url: docs/reference/changed-features/implicit-conversions.html
+            - title: Overload Resolution
+              url: docs/reference/changed-features/overload-resolution.html
             - title: Vararg Patterns
               url: docs/reference/changed-features/vararg-patterns.html
             - title: Pattern matching
diff --git a/tests/pos/i6116.scala b/tests/pos/i6116.scala
new file mode 100644
index 000000000000..159f132b2cb2
--- /dev/null
+++ b/tests/pos/i6116.scala
@@ -0,0 +1,14 @@
+class Test {
+  def f(x: Int)(y: String): Int = ???
+  def f(x: Int)(y: Int): Int = ???
+
+  f(3)("")       // ok
+  f(3)(4)        // ok
+
+  def g(x: Int)(y: Int)(z: Int): Int = ???
+  def g(x: Int)(y: Int)(z: String): Int = ???
+
+  g(2)(3)(4)     // ok
+  g(2)(3)("")    // ok
+}
+