Allow building with cmake --compile-no-warning-as-error. (#2401)

In CMake 3.24+, there is built-in support for adding -Werror that does
not require adding -Werror explicitly, and allows it to be downgraded to
a warning if the user wants that. Use this, to account for warnings that
have false positives.

Author: hvdijk

CMakeLists.txt

@@ -100,7 +100,11 @@ if(CMAKE_COMPILER_IS_GNUCC OR "${CMAKE_CXX_COMPILER_ID}" MATCHES "(Apple)?Clang"
     add_cxx_flag_if_supported(-Wmisleading-indentation)
     add_cxx_flag_if_supported(-Wunused-function)
     add_cxx_flag_if_supported(-Wunused-variable)
-    add_cxx_flag_if_supported(-Werror)
+    if(CMAKE_VERSION VERSION_GREATER_EQUAL "3.24")
+      set(CMAKE_COMPILE_WARNING_AS_ERROR ON)
+    else()
+      add_cxx_flag_if_supported(-Werror)
+    endif()
     if(NOT CMAKE_BUILD_TYPE MATCHES "Release|RelWithDebInfo|MinSizeRel")
         # Enable more warnings if not doing a release build.
         add_cxx_flag_if_supported(-Wall)

test_conformance/common/vulkan_wrapper/CMakeLists.txt

@@ -6,6 +6,7 @@ set(VULKAN_WRAPPER_SOURCES
 )
 
 # needed by Vulkan wrapper to compile
+set(CMAKE_COMPILE_WARNING_AS_ERROR OFF)
 add_cxx_flag_if_supported(-Wmisleading-indentation)
 add_cxx_flag_if_supported(-Wno-narrowing)
 add_cxx_flag_if_supported(-Wno-format)

test_conformance/extensions/cl_khr_external_semaphore/CMakeLists.txt

@@ -17,6 +17,7 @@ include_directories(${CMAKE_CURRENT_SOURCE_DIR})
 include_directories (${CLConform_INCLUDE_DIR})
 
 list(APPEND CLConform_LIBRARIES vulkan_wrapper)
+set(CMAKE_COMPILE_WARNING_AS_ERROR OFF)
 set(CMAKE_CXX_FLAGS "-fpermissive")
 
 include_directories("../../common/vulkan_wrapper")

test_conformance/vulkan/CMakeLists.txt

@@ -1,6 +1,7 @@
 set (MODULE_NAME VULKAN)
 
 list(APPEND CLConform_LIBRARIES vulkan_wrapper)
+set(CMAKE_COMPILE_WARNING_AS_ERROR OFF)
 set(CMAKE_CXX_FLAGS "-fpermissive")
 if(WIN32)
     set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -DVK_USE_PLATFORM_WIN32_KHR")