From cb272fefc6836265ec816508c345780560558fbb Mon Sep 17 00:00:00 2001
From: Gerard Basler <gerard.basler@gmail.com>
Date: Mon, 29 Dec 2014 20:34:59 +0100
Subject: Bugfix: Implement missing `equals` method for `Sym`.

---
 src/compiler/scala/tools/nsc/transform/patmat/Logic.scala | 13 ++++++++++++-
 1 file changed, 12 insertions(+), 1 deletion(-)

diff --git a/src/compiler/scala/tools/nsc/transform/patmat/Logic.scala b/src/compiler/scala/tools/nsc/transform/patmat/Logic.scala
index 9f24d5122a..da6527bc0b 100644
--- a/src/compiler/scala/tools/nsc/transform/patmat/Logic.scala
+++ b/src/compiler/scala/tools/nsc/transform/patmat/Logic.scala
@@ -122,9 +122,20 @@ trait Logic extends Debugging  {
 
     // symbols are propositions
     final class Sym private[PropositionalLogic] (val variable: Var, val const: Const) extends Prop {
+
+      override def equals(other: scala.Any): Boolean = other match {
+        case that: Sym => this.variable == that.variable &&
+          this.const == that.const
+        case _         => false
+      }
+
+      override def hashCode(): Int = {
+        variable.hashCode * 41 + const.hashCode
+      }
+
       private val id: Int = Sym.nextSymId
 
-      override def toString = variable + "=" + const + "#" + id
+      override def toString = s"$variable=$const#$id"
     }
 
     object Sym {
-- 
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