[REG 6.7->6.8] macOS: FindWrapResolv.cmake fails check_cxx_source_compiles with strict flags (-Werror -Wzero-as-null-pointer-constant)

CMake configuration fails when finding Qt6 Network (or components depending on it like Gui/Widgets) on macOS when using strict compiler flags like -Weverything and -Werror.

The specific failure occurs within the 
FindWrapResolv.cmake
 script, which is new or changed in Qt 6.8. This script uses check_cxx_source_compiles to verify the presence of resolver functions. However, the test code within this check uses res_state statep = 0;.

When compiled with strict flags, specifically -Wzero-as-null-pointer-constant (often enabled by -Wall, -Wextra, or -Weverything) combined with -Werror, this line causes a fatal compilation error because 0 is used instead of nullptr for a pointer type.

This compilation error causes check_cxx_source_compiles to fail, leading 
FindWrapResolv.cmake
 to incorrectly report that the dependency is not found, ultimately causing find_package(Qt6) to fail for components requiring QtNetwork.

This is a regression from Qt 6.7.x where this check was either not present or did not cause issues.

Steps to Reproduce:

Set up a minimal CMake project on macOS.
Configure CMake to use C++20 or later.
Set CMAKE_CXX_FLAGS to include strict checks, crucially -Werror and -Wzero-as-null-pointer-constant (e.g., -Wall -Wextra -Wpedantic -Werror -Wzero-as-null-pointer-constant).
Ensure Qt 6.8.0 or later is available (e.g., via vcpkg or system install).
Add find_package(Qt6 6.8 REQUIRED COMPONENTS Network) (or Gui/Widgets) to 
CMakeLists.txt.

Run CMake configure.

Expected Result:

CMake configures the project successfully, finding Qt6 and its components.

Actual Result:

CMake configuration fails. The error messages typically indicate that WrapResolv could not be found, or that Qt6Network could not be found because its dependency WrapResolv failed. Example CMake output snippet:

...

CMake Error at /path/to/vcpkg_installed/arm64-osx/share/Qt6/Qt6Config.cmake:190 (find_package):
  Found package configuration file:

    /path/to/vcpkg_installed/arm64-osx/share/Qt6Network/Qt6NetworkConfig.cmake

  but it set Qt6Network_FOUND to FALSE so package "Qt6Network" is considered
  to be NOT FOUND.  Reason given by package:

  Qt6Network could not be found because dependency WrapResolv could not be
  found.
(Note: The exact error message might vary slightly depending on which Qt component triggers the find_package call first)

Proposed Fix:

Modify the test code within 
FindWrapResolv.cmake
 to use modern C++: Change:

res_state statep = 0;
to:

res_state statep = nullptr;

Workaround:

A successful workaround is to temporarily clear CMAKE_CXX_FLAGS before calling find_package(Qt6) and restore it afterwards within the 
CMakeLists.txt:

set(ORIGINAL_CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS}")
set(CMAKE_CXX_FLAGS "" CACHE STRING "Temp clear for Qt find" FORCE)
find_package(Qt6 6.8 REQUIRED COMPONENTS Network) # Or other components
set(CMAKE_CXX_FLAGS "${ORIGINAL_CMAKE_CXX_FLAGS}" CACHE STRING "Restore flags" FORCE)