Enable -Wextra -Wno-unused-parameter by default for gcc

src/CMakeLists.txt

@@ -77,7 +77,7 @@ if(MSVC)
         )
 else()
     set(LIB_MATH m)
-    add_compile_options(-Wall) # -Wextra
+    add_compile_options(-Wall -Wextra -Wno-unused-parameter)
 endif()
 
 # =====================================

src/configure.ac

@@ -429,7 +429,7 @@ fi
 
 # If we are compiling with gcc, enable all warnings and make warnings errors.
 if test "$GCC" = yes; then
-    ENABLE_WARNINGS="-Wall"
+    ENABLE_WARNINGS="-Wall -Wextra -Wno-unused-parameter"
 
 	# does this compiler support -Wno-pointer-sign ?
 	AC_MSG_CHECKING([if gcc accepts -Wno-pointer-sign ])