From 4cca17da5c5236c23e32c0a3298e4a097e335a0c Mon Sep 17 00:00:00 2001
From: Miguel Garcia <miguelalfredo.garcia@epfl.ch>
Date: Sat, 7 Jul 2012 21:08:24 +0200
Subject: raise compile time error about impending VerifyError due to unsorted
 lookupswitch (SI-6011)

---
 src/compiler/scala/tools/nsc/backend/jvm/GenASM.scala | 9 +++++++++
 1 file changed, 9 insertions(+)

(limited to 'src/compiler')

diff --git a/src/compiler/scala/tools/nsc/backend/jvm/GenASM.scala b/src/compiler/scala/tools/nsc/backend/jvm/GenASM.scala
index 49a3a13247..32c100b026 100644
--- a/src/compiler/scala/tools/nsc/backend/jvm/GenASM.scala
+++ b/src/compiler/scala/tools/nsc/backend/jvm/GenASM.scala
@@ -1942,6 +1942,15 @@ abstract class GenASM extends SubComponent with BytecodeWriters {
           i += 1
         }
 
+        // check for duplicate keys to avoid "VerifyError: unsorted lookupswitch" (SI-6011)
+        i = 1
+        while (i < keys.length) {
+          if(keys(i-1) == keys(i)) {
+            abort("duplicate keys in SWITCH, can't pick arbitrarily one of them to evict, see SI-6011.")
+          }
+          i += 1
+        }
+
         val keyMin = keys(0)
         val keyMax = keys(keys.length - 1)
 
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