From 6535f0bca658d772efffbfe04ba5f9e625a9b31e Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Vladim=C3=ADr=20=C4=8Cun=C3=A1t?= <vcunat@gmail.com>
Date: Mon, 6 Nov 2017 19:20:21 +0100
Subject: [PATCH] flex: fix with glibc-2.26

It caused segfaults, e.g. when building doxygen.
---
 pkgs/development/tools/parsing/flex/default.nix | 12 +++++++++++-
 1 file changed, 11 insertions(+), 1 deletion(-)

diff --git a/pkgs/development/tools/parsing/flex/default.nix b/pkgs/development/tools/parsing/flex/default.nix
index 92fba47b756f..354126b5457f 100644
--- a/pkgs/development/tools/parsing/flex/default.nix
+++ b/pkgs/development/tools/parsing/flex/default.nix
@@ -1,4 +1,6 @@
-{ stdenv, fetchurl, bison, m4 }:
+{ stdenv, fetchurl, bison, m4
+, fetchpatch, autoreconfHook, help2man
+}:
 
 stdenv.mkDerivation rec {
   name = "flex-${version}";
@@ -9,6 +11,14 @@ stdenv.mkDerivation rec {
     sha256 = "15g9bv236nzi665p9ggqjlfn4dwck5835vf0bbw2cz7h5c1swyp8";
   };
 
+  patches = [(fetchpatch {
+    name = "glibc-2.26.patch";
+    url = "https://raw.githubusercontent.com/lede-project/source/0fb14a2b1ab2f82c"
+        + "/tools/flex/patches/200-build-AC_USE_SYSTEM_EXTENSIONS-in-configure.ac.patch";
+    sha256 = "1aarhcmz7mfrgh15pkj6f7ikxa2m0mllw1i1vscsf1kw5d05lw6f";
+  })];
+  nativeBuildInputs = [ autoreconfHook help2man ];
+
   buildInputs = [ bison ];
 
   propagatedBuildInputs = [ m4 ];