From 994ebd869a8f921eb92b1c49e115a8568414c73f Mon Sep 17 00:00:00 2001
From: Lynix <lynix680@gmail.com>
Date: Tue, 19 Jul 2022 19:03:47 +0200
Subject: [PATCH] Disable -isystem with MinGW on msys2

See https://github.com/msys2/MINGW-packages/issues/10761
---
 .github/workflows/msys2-build.yml | 2 +-
 xmake.lua                         | 7 +++++++
 2 files changed, 8 insertions(+), 1 deletion(-)

diff --git a/.github/workflows/msys2-build.yml b/.github/workflows/msys2-build.yml
index fa77b0982..9772af00f 100644
--- a/.github/workflows/msys2-build.yml
+++ b/.github/workflows/msys2-build.yml
@@ -92,7 +92,7 @@ jobs:
 
     # Setup compilation mode and install project dependencies
     - name: Configure xmake and install dependencies
-      run: xmake config --arch=${{ matrix.arch }} --mode=${{ matrix.mode }} --ccache=n --ffmpeg=y --shadernodes=y --tests=y --unitybuild=y --yes --verbose
+      run: xmake config --arch=${{ matrix.arch }} --mode=${{ matrix.mode }} --ccache=n --ffmpeg=y --shadernodes=y --tests=y --unitybuild=y --yes
 
     # Build the engine
     - name: Build Nazara
diff --git a/xmake.lua b/xmake.lua
index 027e95884..5b27e3e72 100644
--- a/xmake.lua
+++ b/xmake.lua
@@ -208,6 +208,13 @@ if is_plat("windows") then
 elseif is_plat("mingw") then
 	add_cxflags("-Og", "-Wa,-mbig-obj")
 	add_ldflags("-Wa,-mbig-obj")
+
+	if is_subhost("msys", "cygwin") then
+		-- disable -isystem for packages as it's broken on msys2 (see https://github.com/msys2/MINGW-packages/issues/10761)
+		if project.policy("package.include_external_headers") == nil then
+			set_policy("package.include_external_headers", false)
+		end
+	end
 end
 
 for name, module in pairs(modules) do