CMake: Add option to enable -Werror cflag in some areas

It is rather annoying attitude nowadays to use const qualifier all over the
place, including using it for multi-dimensional arrays. This isn't really
supported in GCC prior to version 5.0 because it considers such an arrays
to be a "pointer to a const pointer" which gives implicit casting errors.

It's not possible to disable this particular type of warnings treated as
errors in any GCC version prior to 5.0 as well, meaning currently usage of
-Werror globally in Blender code is not possible at all.

This commit makes it possible to use -Werror in areas which are complaint
with older GCC versions. New advanced CMake options are:

- WITH_COMPOSITOR_WERROR
- WITH_LIBMV_WERROR
- WITH_CYCLES_WERROR

CMakeLists.txt

@@ -221,7 +221,11 @@ mark_as_advanced(WITH_SYSTEM_BULLET)
 option(WITH_GAMEENGINE    "Enable Game Engine" ${_init_GAMEENGINE})
 option(WITH_PLAYER        "Build Player" OFF)
 option(WITH_OPENCOLORIO   "Enable OpenColorIO color management" ${_init_OPENCOLORIO})
-option(WITH_COMPOSITOR    "Enable the tile based nodal compositor" ON)
+
+# Compositor
+option(WITH_COMPOSITOR         "Enable the tile based nodal compositor" ON)
+option(WITH_COMPOSITOR_WERROR  "Treat warnings as errors in compositor code" OFF)
+mark_as_advanced(WITH_COMPOSITOR_WERROR)
 
 # GHOST Windowing Library Options
 option(WITH_GHOST_DEBUG   "Enable debugging output for the GHOST library" OFF)
@@ -318,9 +322,11 @@ if(UNIX AND NOT APPLE)
 endif()
 
 # Camera/motion tracking
-option(WITH_LIBMV         "Enable libmv structure from motion library" ON)
+option(WITH_LIBMV         "Enable Libmv structure from motion library" ON)
 option(WITH_LIBMV_SCHUR_SPECIALIZATIONS "Enable fixed-size schur specializations." ${_init_LIBMV_SCHUR_SPECIALIZATION})
+option(WITH_LIBMV_WERROR  "Treat warnings as errors in Libmv (and Blender's motion tracking) code")
 mark_as_advanced(WITH_LIBMV_SCHUR_SPECIALIZATIONS)
+mark_as_advanced(WITH_LIBMV_WERROR)
 
 # Freestyle
 option(WITH_FREESTYLE     "Enable Freestyle (advanced edges rendering)" ON)
@@ -354,18 +360,20 @@ if(UNIX AND NOT APPLE)
 endif()
 
 # Cycles
-option(WITH_CYCLES					"Enable cycles Render Engine" ON)
-option(WITH_CYCLES_STANDALONE		"Build cycles standalone application" OFF)
-option(WITH_CYCLES_STANDALONE_GUI	"Build cycles standalone with GUI" OFF)
+option(WITH_CYCLES					"Enable Cycles Render Engine" ON)
+option(WITH_CYCLES_STANDALONE		"Build Cycles standalone application" OFF)
+option(WITH_CYCLES_STANDALONE_GUI	"Build Cycles standalone with GUI" OFF)
 option(WITH_CYCLES_OSL				"Build Cycles with OSL support" ${_init_CYCLES_OSL})
-option(WITH_CYCLES_CUDA_BINARIES	"Build cycles CUDA binaries" OFF)
+option(WITH_CYCLES_CUDA_BINARIES	"Build Cycles CUDA binaries" OFF)
 set(CYCLES_CUDA_BINARIES_ARCH sm_20 sm_21 sm_30 sm_35 sm_50 sm_52 CACHE STRING "CUDA architectures to build binaries for")
 mark_as_advanced(CYCLES_CUDA_BINARIES_ARCH)
 unset(PLATFORM_DEFAULT)
-option(WITH_CYCLES_LOGGING	"Build cycles with logging support" ON)
-option(WITH_CYCLES_DEBUG	"Build cycles with extra debug capabilities" OFF)
+option(WITH_CYCLES_LOGGING	"Build Cycles with logging support" ON)
+option(WITH_CYCLES_DEBUG	"Build Cycles with extra debug capabilities" OFF)
+option(WITH_CYCLES_WERROR	"Treat warnings as errors in Cycles code" OFF)
 mark_as_advanced(WITH_CYCLES_LOGGING)
 mark_as_advanced(WITH_CYCLES_DEBUG)
+mark_as_advanced(WITH_CYCLES_WERROR)
 
 # LLVM
 option(WITH_LLVM					"Use LLVM" OFF)

extern/libmv/CMakeLists.txt

@@ -37,6 +37,11 @@ set(SRC
 	libmv-capi.h
 )
 
+if(WITH_LIBMV_WERROR)
+	ADD_CHECK_C_COMPILER_FLAG(CMAKE_C_FLAGS C_WERROR -Werror)
+	ADD_CHECK_CXX_COMPILER_FLAG(CMAKE_CXX_FLAGS C_WERROR -Werror)
+endif()
+
 if(WITH_LIBMV OR WITH_GTESTS OR (WITH_CYCLES AND WITH_CYCLES_LOGGING))
 	list(APPEND INC
 		third_party/gflags

intern/cycles/CMakeLists.txt

@@ -14,6 +14,11 @@ include(cmake/external_libs.cmake)
 # todo: refactor this code to match scons
 # note: CXX_HAS_SSE is needed in case passing SSE flags fails altogether (gcc-arm)
 
+if(WITH_CYCLES_WERROR)
+	ADD_CHECK_C_COMPILER_FLAG(CMAKE_C_FLAGS C_WERROR -Werror)
+	ADD_CHECK_CXX_COMPILER_FLAG(CMAKE_CXX_FLAGS C_WERROR -Werror)
+endif()
+
 if(NOT WITH_CPU_SSE)
 	set(CXX_HAS_SSE FALSE)
 	set(CXX_HAS_AVX FALSE)

source/blender/blenkernel/CMakeLists.txt

@@ -463,6 +463,20 @@ if(WITH_LIBMV)
 	add_definitions(-DWITH_LIBMV)
 endif()
 
+if(WITH_LIBMV_WERROR)
+	if(CMAKE_COMPILER_IS_GNUCC OR CMAKE_C_COMPILER_ID MATCHES "Clang")
+		set_source_files_properties(intern/tracking.c
+		                            intern/tracking_auto.c
+		                            intern/tracking_detect.c
+		                            intern/tracking_plane_tracker.c
+		                            intern/tracking_region_tracker.c
+		                            intern/tracking_solver.c
+		                            intern/tracking_stabilize.c
+		                            intern/tracking_util.c
+		                            PROPERTIES COMPILE_FLAGS -Werror)
+	endif()
+endif()
+
 if(WITH_FFTW3)
 	list(APPEND INC_SYS
 		${FFTW3_INCLUDE_DIRS}

source/blender/compositor/CMakeLists.txt

@@ -540,6 +540,12 @@ set(SRC
 list(APPEND INC
 	${CMAKE_CURRENT_BINARY_DIR}/operations
 )
+
+if(WITH_COMPOSITOR_WERROR)
+	ADD_CHECK_C_COMPILER_FLAG(CMAKE_C_FLAGS C_WERROR -Werror)
+	ADD_CHECK_CXX_COMPILER_FLAG(CMAKE_CXX_FLAGS C_WERROR -Werror)
+endif()
+
 data_to_c(${CMAKE_CURRENT_SOURCE_DIR}/operations/COM_OpenCLKernels.cl
           ${CMAKE_CURRENT_BINARY_DIR}/operations/COM_OpenCLKernels.cl.h SRC)