From be6b461bb9e07df8d93a3cc6432b74550acf12c4 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?J=C3=B6rg=20Thalheim?= <joerg@thalheim.io>
Date: Wed, 28 Nov 2018 10:25:08 +0000
Subject: [PATCH] swig: document why pcre.dev is in nativeBuildInputs

---
 pkgs/development/tools/misc/swig/3.x.nix | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/pkgs/development/tools/misc/swig/3.x.nix b/pkgs/development/tools/misc/swig/3.x.nix
index 7e527bebba1..9dc2b535c09 100644
--- a/pkgs/development/tools/misc/swig/3.x.nix
+++ b/pkgs/development/tools/misc/swig/3.x.nix
@@ -1,4 +1,4 @@
-{ stdenv, fetchFromGitHub, autoconf, automake, libtool, bison, pcre }:
+{ stdenv, fetchFromGitHub, autoconf, automake, libtool, bison, pcre, buildPackages }:
 
 stdenv.mkDerivation rec {
   name = "swig-${version}";
@@ -11,7 +11,10 @@ stdenv.mkDerivation rec {
     sha256 = "1wyffskbkzj5zyhjnnpip80xzsjcr3p0q5486z3wdwabnysnhn8n";
   };
 
+  # for cross-compiling we need pcre.dev in nativeBuildInputs to get pcre-config
   nativeBuildInputs = [ autoconf automake libtool bison pcre.dev ];
+  disallowedReferences = [ buildPackages.pcre.dev ];
+
   buildInputs = [ pcre ];
 
   configureFlags = [ "--without-tcl" ];