From cbc0db08f948a762ee4b3f7f9ded47a034f5d9fa Mon Sep 17 00:00:00 2001
From: David McFarland <corngood@gmail.com>
Date: Tue, 23 May 2017 10:36:56 -0300
Subject: [PATCH] zlib: fix cygwin build

---
 pkgs/development/libraries/zlib/default.nix         |  2 ++
 .../libraries/zlib/disable-cygwin-widechar.patch    | 13 +++++++++++++
 2 files changed, 15 insertions(+)
 create mode 100644 pkgs/development/libraries/zlib/disable-cygwin-widechar.patch

diff --git a/pkgs/development/libraries/zlib/default.nix b/pkgs/development/libraries/zlib/default.nix
index e6468771cd40..2278453c492c 100644
--- a/pkgs/development/libraries/zlib/default.nix
+++ b/pkgs/development/libraries/zlib/default.nix
@@ -17,6 +17,8 @@ stdenv.mkDerivation rec {
     sha256 = "c3e5e9fdd5004dcb542feda5ee4f0ff0744628baf8ed2dd5d66f8ca1197cb1a1";
   };
 
+  patches = stdenv.lib.optional hostPlatform.isCygwin ./disable-cygwin-widechar.patch;
+
   postPatch = stdenv.lib.optionalString stdenv.isDarwin ''
     substituteInPlace configure \
       --replace '/usr/bin/libtool' 'ar' \
diff --git a/pkgs/development/libraries/zlib/disable-cygwin-widechar.patch b/pkgs/development/libraries/zlib/disable-cygwin-widechar.patch
new file mode 100644
index 000000000000..3de4978c3066
--- /dev/null
+++ b/pkgs/development/libraries/zlib/disable-cygwin-widechar.patch
@@ -0,0 +1,13 @@
+diff --git a/gzguts.h b/gzguts.h
+index 990a4d2..6378d46 100644
+--- a/gzguts.h
++++ b/gzguts.h
+@@ -39,7 +39,7 @@
+ #  include <io.h>
+ #endif
+ 
+-#if defined(_WIN32) || defined(__CYGWIN__)
++#if defined(_WIN32)
+ #  define WIDECHAR
+ #endif
+