Add -Wswitch-enum to default GCC/Clang build options

This is now consistent with the warnings that Visual Studio would generate,
which warns about missing enum cases in switch/case even when a default: is
present.

Author: tautschnig

CMakeLists.txt

@@ -24,7 +24,7 @@ if("${CMAKE_CXX_COMPILER_ID}" STREQUAL "Clang" OR
     set(CMAKE_CXX_FLAGS_RELEASE "-O2")
     set(CMAKE_CXX_FLAGS_RELWITHDEBINFO "-O2 -g")
     #   Enable lots of warnings
-    set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -Wall -Wpedantic -Werror -Wno-deprecated-declarations")
+    set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -Wall -Wpedantic -Werror -Wno-deprecated-declarations -Wswitch-enum")
 elseif("${CMAKE_CXX_COMPILER_ID}" STREQUAL "MSVC")
     #   This would be the place to enable warnings for Windows builds, although
     #   config.inc doesn't seem to do that currently

src/config.inc

@@ -5,7 +5,7 @@ BUILD_ENV = AUTO
 ifeq ($(BUILD_ENV),MSVC)
   #CXXFLAGS += /Wall /WX
 else
-  CXXFLAGS += -Wall -pedantic -Werror -Wno-deprecated-declarations
+  CXXFLAGS += -Wall -pedantic -Werror -Wno-deprecated-declarations -Wswitch-enum
 endif
 
 # Select optimisation or debug info