Fix SI-5879.

Fix a bug where a key in an immutable hash map
have the corresponding value different in the iteration
than when doing lookup. This use to happen after calling
`merge`.

Fix the order in which a key-value pair appears in
the collision resolution function - the first argument
always comes from the `this` hash map.

Deprecate `merge` in favour of `merged`, as this is
a pure method.
As an added benefit, the syntax for invoking `merge`
is now nicer.

1 files changed, 74 insertions, 0 deletions

diff --git a/test/files/run/t5879.scala b/test/files/run/t5879.scala
new file mode 100644
index 0000000000..e1c07fc4c2
--- /dev/null
+++ b/test/files/run/t5879.scala
@@ -0,0 +1,74 @@
+import collection.immutable.HashMap
+
+
+object Test {
+  
+  def main(args: Array[String]) {
+    resolveDefault()
+    resolveFirst()
+    resolveSecond()
+    resolveMany()
+  }
+  
+  def resolveDefault() {
+    val a = HashMap(1 -> "1")
+    val b = HashMap(1 -> "2")
+    
+    val r = a.merged(b)(null)
+    println(r)
+    println(r(1))
+    
+    val rold = a.merge(b)
+    println(rold)
+    println(rold(1))
+  }
+  
+  def resolveFirst() {
+    val a = HashMap(1 -> "1")
+    val b = HashMap(1 -> "2")
+    def collision(a: (Int, String), b: (Int, String)) = {
+      println(a)
+      a
+    }
+    
+    val r = a.merged(b) { collision }
+    println(r)
+    println(r(1))
+    
+    val rold = a.merge(b, collision)
+    println(rold)
+    println(rold(1))
+  }
+  
+  def resolveSecond() {
+    val a = HashMap(1 -> "1")
+    val b = HashMap(1 -> "2")
+    def collision(a: (Int, String), b: (Int, String)) = {
+      println(b)
+      b
+    }
+    
+    val r = a.merged(b) { collision }
+    println(r)
+    println(r(1))
+    
+    val rold = a.merge(b, collision)
+    println(rold)
+    println(rold(1))
+  }
+  
+  def resolveMany() {
+    val a = HashMap((0 until 100) zip (0 until 100): _*)
+    val b = HashMap((0 until 100) zip (100 until 200): _*)
+    def collision(a: (Int, Int), b: (Int, Int)) = {
+      (a._1, a._2 + b._2)
+    }
+    
+    val r = a.merged(b) { collision }
+    for ((k, v) <- r) assert(v == 100 + 2 * k, (k, v))
+    
+    val rold = a.merge(b, collision)
+    for ((k, v) <- r) assert(v == 100 + 2 * k, (k, v))
+  }
+  
+}