From 71a61d9cbfe4a82b08a7e2ae5adeb6b5353939e6 Mon Sep 17 00:00:00 2001
From: Matthias Melcher <github@matthiasm.com>
Date: Mon, 4 Nov 2024 20:26:49 +0100
Subject: [PATCH] Using try_run to get __MAC_OS_X_VERSION_MAX_ALLOWED (#1105)

---
 CMake/macOSMaxAllowed.c |  8 ++++++++
 CMake/setup.cmake       | 17 +++++++++++++++--
 2 files changed, 23 insertions(+), 2 deletions(-)
 create mode 100644 CMake/macOSMaxAllowed.c

diff --git a/CMake/macOSMaxAllowed.c b/CMake/macOSMaxAllowed.c
new file mode 100644
index 000000000..625bcb6af
--- /dev/null
+++ b/CMake/macOSMaxAllowed.c
@@ -0,0 +1,8 @@
+#include <Availability.h>
+#include <stdio.h>
+
+int main(int argc, char **argv) {
+  unsigned int ver = __MAC_OS_X_VERSION_MAX_ALLOWED;
+  printf("%d.%d.%d", ver/10000, (ver/100)%100, ver%100);
+  return 0;
+}
diff --git a/CMake/setup.cmake b/CMake/setup.cmake
index dee004ccf..8c06f2782 100644
--- a/CMake/setup.cmake
+++ b/CMake/setup.cmake
@@ -117,6 +117,19 @@ if(APPLE)
   set(HAVE_VSNPRINTF 1)
   set(HAVE_SCANDIR 1)
   set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -Wno-deprecated")
+  # Retrieve the value of the macOS compile-time macro
+  # __MAC_OS_X_VERSION_MAX_ALLOWED. This is needed to decide which
+  # frameworks must be linked later.
+  try_run(
+    RUN_RESULT COMPILE_RESULT
+    SOURCES ${CMAKE_CURRENT_SOURCE_DIR}/CMake/macOSMaxAllowed.c
+    RUN_OUTPUT_VARIABLE MAC_OS_X_VERSION_MAX_ALLOWED
+  )
+  if (NOT COMPILE_RESULT)
+    set(MAC_OS_X_VERSION_MAX_ALLOWED ${CURRENT_OSX_VERSION})
+  endif()
+  fl_debug_var(CMAKE_OSX_DEPLOYMENT_TARGET)
+  fl_debug_var(MAC_OS_X_VERSION_MAX_ALLOWED)
   if(FLTK_BACKEND_X11)
     if(NOT(${CMAKE_SYSTEM_VERSION} VERSION_LESS 17.0.0)) # a.k.a. macOS version ≥ 10.13
       set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -D_LIBCPP_HAS_THREAD_API_PTHREAD")
@@ -124,10 +137,10 @@ if(APPLE)
   else()
     set(FLTK_COCOA_FRAMEWORKS "-framework Cocoa")
     if (NOT (CMAKE_OSX_ARCHITECTURES STREQUAL "ppc" OR CMAKE_OSX_ARCHITECTURES STREQUAL "i386"))
-      if(${CMAKE_SYSTEM_VERSION} VERSION_GREATER_EQUAL 20.0) # a.k.a. macOS version ≥ 11.0
+      if(${MAC_OS_X_VERSION_MAX_ALLOWED} VERSION_GREATER_EQUAL 11.0)
         list(APPEND FLTK_COCOA_FRAMEWORKS "-weak_framework UniformTypeIdentifiers")
       endif()
-      if(${CMAKE_SYSTEM_VERSION} VERSION_GREATER_EQUAL 24.0) # a.k.a. macOS version ≥ 15.0
+      if(${MAC_OS_X_VERSION_MAX_ALLOWED} VERSION_GREATER_EQUAL 15.0)
         list(APPEND FLTK_COCOA_FRAMEWORKS "-weak_framework ScreenCaptureKit")
       endif()
     endif()