From 83fdd2ee995f470cc66b4689d117dab53458feff Mon Sep 17 00:00:00 2001
From: Brent Cook <busterb@gmail.com>
Date: Tue, 4 Jul 2023 12:36:57 +0300
Subject: [PATCH] make cross compilation possible on macOS with CMake

Sync CMAKE_SYSTEM_PROCESSOR to CMAKE_OSX_ARCHITECTURES. This doesn't
support universal binaries, but does allow cross-compiling for a single
architecture by setting -DCMAKE_OSX_ARCHITECTURES=(arm64|x86_64)
---
 CMakeLists.txt | 9 +++++++++
 1 file changed, 9 insertions(+)

diff --git a/CMakeLists.txt b/CMakeLists.txt
index 2f35f89..ef99dc7 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -299,6 +299,15 @@ if(HAVE_NETINET_IP_H)
 	add_definitions(-DHAVE_NETINET_IP_H)
 endif()
 
+# This isn't ready for universal binaries yet, since we do conditional
+# compilation based on the architecture, but this makes cross compiling for a
+# single architecture work on macOS at least.
+#
+# Don't set CMAKE_OSX_ARCHITECTURES to more than a single value for now.
+if(APPLE)
+	set(CMAKE_SYSTEM_PROCESSOR "${CMAKE_OSX_ARCHITECTURES}")
+endif()
+
 if("${CMAKE_SYSTEM_PROCESSOR}" MATCHES "(aarch64|arm64)")
 	set(HOST_AARCH64 true)
 elseif("${CMAKE_SYSTEM_PROCESSOR}" MATCHES "arm")