CMake option to treat warnings as errors

appveyor.yml

@@ -164,7 +164,7 @@ environment:
 before_build:
   - echo Running cmake...
   - cd c:\projects\libexpat
-  - cmake -G"%GENERATOR%" expat
+  - cmake -DWARNINGS_AS_ERRORS=ON -G"%GENERATOR%" expat
 
 build:
   parallel: true                  # enable MSBuild parallel builds

expat/CMakeLists.txt

@@ -47,6 +47,7 @@ endif()
 set(XML_CONTEXT_BYTES 1024 CACHE STRING "Define to specify how much context to retain around the current parse point")
 option(XML_DTD "Define to make parameter entity parsing functionality available" ON)
 option(XML_NS "Define to make XML Namespaces functionality available" ON)
+option(WARNINGS_AS_ERRORS "Treat all compiler warnings as errors" OFF)
 if(NOT WIN32)
     option(XML_DEV_URANDOM "Define to include code reading entropy from `/dev/urandom'." ON)
     if(XML_DEV_URANDOM)
@@ -75,6 +76,13 @@ set(EXTRA_COMPILE_FLAGS)
 if(FLAG_NO_STRICT_ALIASING)
     set(EXTRA_COMPILE_FLAGS "${EXTRA_COMPILE_FLAGS} -fno-strict-aliasing")
 endif()
+if (WARNINGS_AS_ERRORS)
+    if(MSVC)
+        add_definitions(/WX)
+    else(MSVC)
+        set(EXTRA_COMPILE_FLAGS "${EXTRA_COMPILE_FLAGS} -Werror")
+    endif(MSVC)
+endif(WARNINGS_AS_ERRORS)
 set(CMAKE_C_FLAGS "${CMAKE_C_FLAGS} ${EXTRA_COMPILE_FLAGS}")
 set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} ${EXTRA_COMPILE_FLAGS}")