Conan: Fix iOS builds

Conan passes some autodetected iOS related CMake options like
CMAKE_SYSTEM_NAME, CMAKE_OSX_ARCHITECTURES, CMAKE_OSX_SYSROOT,
which apparently don't work out of the box.

- Explicitly pass 'iOS' for CMAKE_SYSTEM_NAME
- Remove the explicit sysroot 'CMAKE_OSX_SYSROOT', let CMake detect
  the sysroots, to ensure that multi-arch builds work.
- Remove the conan provided architecture 'CMAKE_OSX_ARCHITECTURES',
  instead rely on the architectures set by the Qt toolchain file,
  which with official Qt packages most likely means multi-arch iOS.

Task-number: QTBUG-89020
Pick-to: 6.0 dev
Change-Id: I3c559f00f9391edf68bf88348baae561dc5f0991
Reviewed-by: Alexandru Croitor <alexandru.croitor@qt.io>
Reviewed-by: Mike Krus <mike.krus@kdab.com>

1 files changed, 13 insertions, 0 deletions

diff --git a/conanfile.py b/conanfile.py
index 42558025f..02927ec60 100644
--- a/conanfile.py
+++ b/conanfile.py
@@ -95,6 +95,19 @@ class Qt3D(ConanFile):
             cmake.definitions["ANDROID_SDK_ROOT"] = self._read_env('ANDROID_SDK_ROOT')
             cmake.definitions["ANDROID_NDK_ROOT"] = self._read_env('ANDROID_NDK_ROOT')
 
+        if self.settings.os == "iOS":
+            # Instead of Conan's auto-added 'Darwin', explicitly pass 'iOS'.
+            cmake.definitions["CMAKE_SYSTEM_NAME"] = "iOS"
+
+            # Remove the explicit sysroot, let CMake detect the sysroots, to ensure
+            # that multi-arch builds work.
+            del cmake.definitions["CMAKE_OSX_SYSROOT"]
+
+            # Remove the conan provided architecture, instead rely on the architectures set
+            # by the Qt toolchain file, which with official Qt packages most likely means
+            # multi-arch iOS.
+            del cmake.definitions["CMAKE_OSX_ARCHITECTURES"]
+
         for c in [ 'assimp', 'opengl_renderer', 'rhi_renderer']:
             value = os.environ.get('qt3d_' + c)
             if value: