Fix macOS build with CMake 4.x and Xcode 16+

[karlingen]

Problem

Building BambuStudio on macOS fails with CMake ≥ 4.0 and Xcode 16+ (AppleClang 18+) due to several issues:

1. CMake 4.x removed compatibility with cmake_minimum_required < 3.5, causing multiple dependency sub-builds (Boost, OpenSSL, wxWidgets cotire, etc.) to fail during configuration.

2. Assimp's bundled zlib defines #define fdopen(fd,mode) NULL in zutil.h, which conflicts with the macOS SDK's fdopen declaration in _stdio.h starting with Xcode 16, producing:

   error: expected identifier or '('
   FILE    *fdopen(int, const char *) ...
   

3. Clipper2's -Werror causes the build to fail because the parent CMakeLists.txt adds -Wno-error=enum-constexpr-conversion (line 286), which is an unrecognized warning option on some AppleClang versions. Combined with Clipper2's -Werror, this triggers -Werror,-Wunknown-warning-option.

4. constexpr enum casts in wxMediaCtrl2.h and MediaPlayCtrl.h fail with newer Clang, which enforces stricter rules for constexpr with unscoped enum types:

   error: constexpr variable 'MEDIASTATE_BUFFERING' must be initialized by a constant expression
   

5. AMSMaterialsSetting.cpp calls obj->get_extruder_id_by_ams_id(), a method that does not exist on MachineObject. This is a code bug that fails on any compiler.

Changes

deps/deps-macos.cmake

Add -DCMAKE_POLICY_VERSION_MINIMUM=3.5 to DEP_CMAKE_OPTS so it propagates to all ExternalProject_Add sub-builds via bambustudio_add_cmake_project.

Note: Builders using CMake 4.x also need to set CMAKE_POLICY_VERSION_MINIMUM=3.5 as an environment variable during the build to cover try_compile() calls (e.g., wxWidgets' cotire test). This should be documented in the wiki.

deps/Assimp/Assimp.cmake

Change ASSIMP_BUILD_ZLIB from ON to OFF. This uses the system zlib instead of Assimp's bundled copy, which is the standard approach on macOS where system zlib is always available.

src/clipper2/CMakeLists.txt

Add -Wno-unknown-warning-option alongside -Werror for non-Windows builds. This prevents the build from failing when the parent project adds warning flags that the current compiler version doesn't recognize.

src/slic3r/GUI/wxMediaCtrl2.h and src/slic3r/GUI/MediaPlayCtrl.h

Change static constexpr wxMediaState to static const wxMediaState for custom media state constants. Casting integer values to an unscoped enum in a constexpr context is rejected by Clang 18+ (Xcode 16+). Using const preserves identical runtime behavior.

src/slic3r/GUI/AMSMaterialsSetting.cpp

Replace call to non-existent obj->get_extruder_id_by_ams_id() with obj->GetFilaSystem()->GetExtruderIdByAmsId(), which is the correct API used elsewhere in the same file (e.g., lines 597 and 1025).

Build environment tested

• macOS: arm64 (Apple Silicon)
• Xcode: 16.4.1
• CMake: 4.3.2 (Homebrew)
• Deployment target: 10.15

Wiki update suggestion

The Mac Compile Guide should note that CMake 4.x users need to prefix build commands with:

export CMAKE_POLICY_VERSION_MINIMUM=3.5

or use CMake 3.x until upstream dependencies update their cmake_minimum_required() declarations.