[build] cmake: Add NO_WERROR option to disable -Werror (#6071)

CMakeLists.txt

@@ -82,6 +82,9 @@ option(USE_SYSTEM_EIGEN "Use system eigen" OFF)
 # Options for location of OpenCV Java.
 set(OPENCV_JAVA_INSTALL_DIR "" CACHE PATH "Location to search for the OpenCV jar file")
 
+# Options for compilation flags.
+option(NO_WERROR "Disable -Werror flag during compilation" OFF)
+
 # Set default build type to release with debug info (i.e. release mode optimizations
 # are performed, but debug info still exists).
 if(NOT CMAKE_BUILD_TYPE)

README-CMAKE.md

@@ -63,6 +63,8 @@ The following build options are available:
   * TODO
 * `OPENCV_JAVA_INSTALL_DIR`
   * Set this option to the location of the archive of the OpenCV Java bindings (it should be called opencv-xxx.jar, with the x'es being version numbers). NOTE: set it to the LOCATION of the file, not the file itself!
+* `NO_WERROR` (OFF Default)
+  * This option will disable the `-Werror` compilation flag for non-MSVC builds.
 
 ## Build Setup
 

cmake/modules/CompileWarnings.cmake

@@ -1,9 +1,17 @@
 macro(wpilib_target_warnings target)
     if(NOT MSVC)
-        target_compile_options(
-            ${target}
-            PRIVATE -Wall -pedantic -Wextra -Werror -Wno-unused-parameter ${WPILIB_TARGET_WARNINGS}
+        set(WARNING_FLAGS
+            -Wall
+            -pedantic
+            -Wextra
+            -Wno-unused-parameter
+            ${WPILIB_TARGET_WARNINGS}
         )
+        if(NOT NO_WERROR)
+            set(WARNING_FLAGS ${WARNING_FLAGS} -Werror)
+        endif()
+
+        target_compile_options(${target} PRIVATE ${WARNING_FLAGS})
     else()
         target_compile_options(
             ${target}