Enable additional warnings with GCC/Clang to match Visual Studio

Author: tautschnig

CMakeLists.txt

@@ -78,6 +78,7 @@ if("${CMAKE_CXX_COMPILER_ID}" STREQUAL "GNU")
     #   Enable lots of warnings
     set(CMAKE_CXX_FLAGS
         "${CMAKE_CXX_FLAGS} -Wall -Wpedantic -Werror -Wswitch-enum \
+         -Wextra -Wconversion \
          -Wno-deprecated-declarations -Wno-maybe-uninitialized")
 elseif("${CMAKE_CXX_COMPILER_ID}" STREQUAL "Clang" OR
        "${CMAKE_CXX_COMPILER_ID}" STREQUAL "AppleClang")
@@ -86,7 +87,9 @@ elseif("${CMAKE_CXX_COMPILER_ID}" STREQUAL "Clang" OR
     set(CMAKE_CXX_FLAGS_RELWITHDEBINFO "-O2 -g")
     #   Enable lots of warnings
     set(CMAKE_CXX_FLAGS
-        "${CMAKE_CXX_FLAGS} -Wall -Wpedantic -Werror -Wswitch-enum -Wno-deprecated-declarations")
+        "${CMAKE_CXX_FLAGS} -Wall -Wpedantic -Werror -Wswitch-enum \
+         -Wextra -Wconversion \
+         -Wno-deprecated-declarations")
 elseif("${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

@@ -52,7 +52,7 @@ ifeq ($(BUILD_ENV),MSVC)
   CXXFLAGS += /wd4619
 else
   CXXFLAGS += -Wall -pedantic -Werror -Wswitch-enum
-  CXXFLAGS += -Wno-deprecated-declarations
+  CXXFLAGS += -Wno-deprecated-declarations -Wextra -Wconversion
   # GCC only, silence clang warning
   CXXFLAGS += -Wno-maybe-uninitialized -Wno-unknown-warning-option
 endif