From 6a848de95d9e74642efe1488b89a0fc53e8a5256 Mon Sep 17 00:00:00 2001
From: Rick van Schijndel <rol3517@gmail.com>
Date: Sun, 19 Sep 2021 21:56:56 +0200
Subject: [PATCH 1/2] stdenv: add llvm-config to meson cross file

This is e.g. required to get mesa cross-compiling, but is useful for everyone depending on libllvm
---
 pkgs/stdenv/generic/make-derivation.nix | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/pkgs/stdenv/generic/make-derivation.nix b/pkgs/stdenv/generic/make-derivation.nix
index 56cfa0c503f8..8fa306370494 100644
--- a/pkgs/stdenv/generic/make-derivation.nix
+++ b/pkgs/stdenv/generic/make-derivation.nix
@@ -305,6 +305,9 @@ else let
           cpu_family = '${cpuFamily stdenv.targetPlatform}'
           cpu = '${stdenv.targetPlatform.parsed.cpu.name}'
           endian = ${if stdenv.targetPlatform.isLittleEndian then "'little'" else "'big'"}
+
+          [binaries]
+          llvm-config = 'llvm-config-native'
         '';
       in [ "--cross-file=${crossFile}" ] ++ mesonFlags;
     } // lib.optionalAttrs (attrs.enableParallelBuilding or false) {

From 5d30f708b952a5f86a5df33468a03ce4dff59b24 Mon Sep 17 00:00:00 2001
From: Rick van Schijndel <rol3517@gmail.com>
Date: Sun, 19 Sep 2021 21:57:33 +0200
Subject: [PATCH 2/2] mesa: add llvm as dependency for llvm-config-native

Fixes https://github.com/NixOS/nixpkgs/issues/136926
---
 pkgs/development/libraries/mesa/default.nix | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/pkgs/development/libraries/mesa/default.nix b/pkgs/development/libraries/mesa/default.nix
index 1d7b73a54196..035ff3b6e9c3 100644
--- a/pkgs/development/libraries/mesa/default.nix
+++ b/pkgs/development/libraries/mesa/default.nix
@@ -93,6 +93,10 @@ self = stdenv.mkDerivation {
     ++ lib.optional stdenv.isLinux "driversdev"
     ++ lib.optional enableOpenCL "opencl";
 
+  preConfigure = ''
+    PATH=${llvmPackages.libllvm.dev}/bin:$PATH
+  '';
+
   # TODO: Figure out how to enable opencl without having a runtime dependency on clang
   mesonFlags = [
     "--sysconfdir=/etc"