CMake: demote -Wnullability-completeness to warning for unity buildsHEADdev

Unity builds currently fail on macos with -Werror, due to
-Wnullability-completeness. It seems that apple's system headers don't
have every NS_ASSUME_NONNULL_BEGIN followed by a NS_ASSUME_NONNULL_END,
which seems to leak into our code.
Demoting the errors to a warning to make -Werror builds pass again.

Pick-to: 6.10
Change-Id: I70d8ae33bf57b87feac7bb33b929b74f8cd60504
Reviewed-by: Tor Arne Vestbø <[email protected]>
Reviewed-by: Alexey Edelev <[email protected]>

1 files changed, 12 insertions, 0 deletions

diff --git a/cmake/QtInternalTargets.cmake b/cmake/QtInternalTargets.cmake
index a1f4cb7281c..1b0adccd5b5 100644
--- a/cmake/QtInternalTargets.cmake
+++ b/cmake/QtInternalTargets.cmake
@@ -94,6 +94,18 @@ function(qt_internal_set_warnings_are_errors_flags target target_scope)
             ${language_args}
         )
     endif()
+    if(APPLE)
+        qt_internal_add_compiler_dependent_flags("${target}" ${target_scope}
+            COMPILERS CLANG AppleClang
+                CONDITIONS $<BOOL:$<TARGET_PROPERTY:UNITY_BUILD>>
+                    OPTIONS
+                        -Wno-error=nullability-completeness
+            COMMON_CONDITIONS
+                ${common_conditions}
+            LANGUAGES
+                OBJCXX
+        )
+    endif()
     # Other options are gated at compile time that are not likely to change between different build
     # environments of other modules.
     if(ANDROID)