closes https://github.com/assimp/assimp/issues/3103: always enable warnings as errors .

CMakeLists.txt

@@ -108,10 +108,6 @@ OPTION ( ASSIMP_ERROR_MAX
   "Enable all warnings."
   OFF
 )
-OPTION ( ASSIMP_WERROR
-  "Treat warnings as errors."
-  OFF
-)
 OPTION ( ASSIMP_ASAN
   "Enable AddressSanitizer."
   OFF
@@ -243,7 +239,15 @@ IF( UNIX )
   INCLUDE(GNUInstallDirs)
 ENDIF()
 
-# Grouped compiler settings
+# enable warnings as errors ########################################
+IF (MSVC)
+  ADD_COMPILE_OPTIONS(/WX)
+ELSE()
+  SET(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -Werror")
+  SET(CMAKE_C_FLAGS "${CMAKE_C_FLAGS} -Werror")
+ENDIF()
+
+# Grouped compiler settings ########################################
 IF ((CMAKE_C_COMPILER_ID MATCHES "GNU") AND NOT CMAKE_COMPILER_IS_MINGW)
   IF(NOT ASSIMP_HUNTER_ENABLED)
     SET(CMAKE_CXX_FLAGS "-fPIC -std=c++0x ${CMAKE_CXX_FLAGS}")
@@ -311,16 +315,6 @@ IF (ASSIMP_ERROR_MAX)
   ENDIF()
 ENDIF()
 
-IF (ASSIMP_WERROR)
-  MESSAGE(STATUS "Treating warnings as errors")
-  IF (MSVC)
-    ADD_COMPILE_OPTIONS(/WX)
-  ELSE()
-    SET(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -Werror")
-    SET(CMAKE_C_FLAGS "${CMAKE_C_FLAGS} -Werror")
-  ENDIF()
-ENDIF()
-
 IF (ASSIMP_ASAN)
   MESSAGE(STATUS "AddressSanitizer enabled")
   SET(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -fsanitize=address")