From 12b72485d873534bcce0b0564c99d89d6b1aa964 Mon Sep 17 00:00:00 2001
From: Hubert Plociniczak <hubert.plociniczak@gmail.com>
Date: Wed, 27 Jun 2012 15:43:44 +0200
Subject: Closes SI-5969.

Assumption that we enter tryTwice when inferring
the right alternative with an empty buffer is
wrong.
In this particular bug it manifested itself on
if/then/else which share the same context and 'else'
branch was simply flushing the buffer with an
error from the 'then' branch.
---
 src/compiler/scala/tools/nsc/typechecker/Infer.scala | 7 ++++++-
 1 file changed, 6 insertions(+), 1 deletion(-)

(limited to 'src/compiler')

diff --git a/src/compiler/scala/tools/nsc/typechecker/Infer.scala b/src/compiler/scala/tools/nsc/typechecker/Infer.scala
index 688dcd91ac..e1aabb5469 100644
--- a/src/compiler/scala/tools/nsc/typechecker/Infer.scala
+++ b/src/compiler/scala/tools/nsc/typechecker/Infer.scala
@@ -1612,6 +1612,9 @@ trait Infer {
         val saved = context.state
         var fallback = false
         context.setBufferErrors()
+        // Need to test first attempt with an empty buffer.
+        // Otherwise, any previous errors will get lost.
+        val errorsToRestore = context.flushAndReturnBuffer()
         try {
           context.withImplicitsDisabled(infer(false))
           if (context.hasErrors) {
@@ -1625,8 +1628,10 @@ trait Infer {
           case ex: TypeError        => // recoverable cyclic references
             context.restoreState(saved)
             if (!fallback) infer(true) else ()
+        } finally {
+          context.restoreState(saved)
+          context.updateBuffer(errorsToRestore)
         }
-        context.restoreState(saved)
       }
       else infer(true)
     }
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