Added CMake option to set the compiler warning to max (-Wall /W4). Off by default

Build.md

@@ -77,6 +77,7 @@ The cmake-build-environment provides options to configure the build. The followi
 - **ASSIMP_BUILD_SAMPLES ( default OFF )**: If the official samples are built as well (needs Glut).
 - **ASSIMP_BUILD_TESTS ( default ON )**: If the test suite for Assimp is built in addition to the library.
 - **ASSIMP_COVERALLS ( default OFF )**: Enable this to measure test coverage.
+- **ASSIMP_ERROR_MAX( default OFF)**: Enable all warnings.
 - **ASSIMP_WERROR( default OFF )**: Treat warnings as errors.
 - **ASSIMP_ASAN ( default OFF )**: Enable AddressSanitizer.
 - **ASSIMP_UBSAN ( default OFF )**: Enable Undefined Behavior sanitizer.

CMakeLists.txt

@@ -100,6 +100,10 @@ OPTION ( ASSIMP_COVERALLS
   "Enable this to measure test coverage."
   OFF
 )
+OPTION ( ASSIMP_ERROR_MAX
+  "Enable all warnings."
+  OFF
+)
 OPTION ( ASSIMP_WERROR
   "Treat warnings as errors."
   OFF
@@ -294,6 +298,16 @@ IF (ASSIMP_COVERALLS)
   SET(CMAKE_C_FLAGS "${CMAKE_C_FLAGS} -g -O0 -fprofile-arcs -ftest-coverage")
 ENDIF()
 
+IF (ASSIMP_ERROR_MAX)
+  MESSAGE(STATUS "Turning on all warnings")
+  IF (MSVC)
+    ADD_COMPILE_OPTIONS(/W4) # NB: there is a /Wall option, pedantic mode
+  ELSE()
+    SET(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -Wall")
+    SET(CMAKE_C_FLAGS "${CMAKE_C_FLAGS} -Wall")
+  ENDIF()
+ENDIF()
+
 IF (ASSIMP_WERROR)
   MESSAGE(STATUS "Treating warnings as errors")
   IF (MSVC)