From 6844d679fcbef8b298080cbfde129c1352f5bfe9 Mon Sep 17 00:00:00 2001
From: Andreas Rumpf <rumpf_a@web.de>
Date: Thu, 25 Oct 2018 07:52:27 +0200
Subject: [PATCH] nimpretty: fixes #9499

(cherry picked from commit 5fd2827ab6a5caeb2ee0116c5561d7d409ff74d9)
---
 compiler/layouter.nim | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/compiler/layouter.nim b/compiler/layouter.nim
index 9ddfbeabcd..b4321463cb 100644
--- a/compiler/layouter.nim
+++ b/compiler/layouter.nim
@@ -55,9 +55,13 @@ proc openEmitter*(em: var Emitter, cache: IdentCache;
   em.lastLineNumber = 1
 
 proc closeEmitter*(em: var Emitter) =
+  if fileExists(em.config.outFile) and readFile(em.config.outFile.string) == em.content:
+    discard "do nothing, see #9499"
+    return
   var f = llStreamOpen(em.config.outFile, fmWrite)
   if f == nil:
     rawMessage(em.config, errGenerated, "cannot open file: " & em.config.outFile.string)
+    return
   f.llStreamWrite em.content
   llStreamClose(f)