From d5aaa463c801cbda3f2f43b70fd780385211bcaf Mon Sep 17 00:00:00 2001
From: Ioannis Giannakas <59056762+igiannakas@users.noreply.github.com>
Date: Sat, 26 Sep 2026 17:20:17 +0100
Subject: [PATCH] Fix MacOS 27 Xcode and Command Line build failures (#15923)

---
 CMakeLists.txt         | 9 +++++++--
 build_release_macos.sh | 4 ++--
 deps/CMakeLists.txt    | 4 ++--
 3 files changed, 11 insertions(+), 6 deletions(-)

diff --git a/CMakeLists.txt b/CMakeLists.txt
index 6f8e994758..3a7b8adf5f 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -56,9 +56,9 @@ You can do this in Environment Variables settings.
 endif ()
 
 if (APPLE)
-    # if CMAKE_OSX_DEPLOYMENT_TARGET is not set, set it to 11.3
+    # if CMAKE_OSX_DEPLOYMENT_TARGET is not set, set it to 12.0 (the lowest Xcode 27 accepts)
     if (NOT CMAKE_OSX_DEPLOYMENT_TARGET)
-        set(CMAKE_OSX_DEPLOYMENT_TARGET "11.3" CACHE STRING "Minimum OS X deployment version" FORCE)
+        set(CMAKE_OSX_DEPLOYMENT_TARGET "12.0" CACHE STRING "Minimum OS X deployment version" FORCE)
     endif ()
     message(STATUS "CMAKE_OSX_DEPLOYMENT_TARGET: ${CMAKE_OSX_DEPLOYMENT_TARGET}")
 endif ()
@@ -279,6 +279,11 @@ if (APPLE)
     endif()
     SET(CMAKE_XCODE_ATTRIBUTE_PRODUCT_BUNDLE_IDENTIFIER "com.orcaslicer.OrcaSlicer")
 
+    # The macOS CI jobs build with Ninja (build_release_macos.sh -x), so the Xcode generator
+    # is not covered. Xcode adds -Wshorten-64-to-32 by default ("Implicit Conversion to 32 Bit
+    # Type"); Ninja/-Wall does not, and under -Werror it fails Xcode builds on code CI accepts.
+    set(CMAKE_XCODE_ATTRIBUTE_GCC_WARN_64_TO_32_BIT_CONVERSION "NO")
+
     message(STATUS "Orca: IS_CROSS_COMPILE: ${IS_CROSS_COMPILE}")
 elseif (CMAKE_SYSTEM_NAME STREQUAL "Linux")
     set(CMAKE_INSTALL_RPATH "$ORIGIN")
diff --git a/build_release_macos.sh b/build_release_macos.sh
index b1de5df2e4..db03cb4ecd 100755
--- a/build_release_macos.sh
+++ b/build_release_macos.sh
@@ -53,7 +53,7 @@ while getopts ":dpa:snt:xbc:i:j:Tuh" opt; do
         echo "   -s: Build slicer only"
         echo "   -u: Build universal app only (requires existing arm64 and x86_64 app bundles)"
         echo "   -n: Nightly build"
-        echo "   -t: Specify minimum version of the target platform, default is 11.3"
+        echo "   -t: Specify minimum version of the target platform, default is 12.0"
         echo "   -x: Use Ninja Multi-Config CMake generator, default is Xcode"
         echo "   -b: Build without reconfiguring CMake"
         echo "   -c: Set CMake build configuration, default is Release"
@@ -95,7 +95,7 @@ if [ -z "$DEPS_CMAKE_GENERATOR" ]; then
 fi
 
 if [ -z "$OSX_DEPLOYMENT_TARGET" ]; then
-  export OSX_DEPLOYMENT_TARGET="11.3"
+  export OSX_DEPLOYMENT_TARGET="12.0"
 fi
 
 if [ -z "$CMAKE_IGNORE_PREFIX_PATH" ]; then
diff --git a/deps/CMakeLists.txt b/deps/CMakeLists.txt
index 0e7141c12c..502e5df071 100644
--- a/deps/CMakeLists.txt
+++ b/deps/CMakeLists.txt
@@ -26,9 +26,9 @@ endif()
 
 cmake_minimum_required(VERSION 3.2)
 if (APPLE)
-    # if CMAKE_OSX_DEPLOYMENT_TARGET is not set, set it to 11.3
+    # if CMAKE_OSX_DEPLOYMENT_TARGET is not set, set it to 12.0 (the lowest Xcode 27 accepts)
     if (NOT CMAKE_OSX_DEPLOYMENT_TARGET)
-        set(CMAKE_OSX_DEPLOYMENT_TARGET "11.3" CACHE STRING "Minimum OS X deployment version" FORCE)
+        set(CMAKE_OSX_DEPLOYMENT_TARGET "12.0" CACHE STRING "Minimum OS X deployment version" FORCE)
     endif ()
     message(STATUS "CMAKE_OSX_DEPLOYMENT_TARGET: ${CMAKE_OSX_DEPLOYMENT_TARGET}")