#if 0 DEF FOO = 0 DEF BAR = 0 #endif #include #include #include #include #if defined(FOO) #define FOO 1 #endif #if defined(BAR) #define BAR 2 #endif #if defined(FOO) typedef struct { } Foo; #endif #if defined(BAR) typedef struct { } Bar; #endif #if defined(FOO) void foo(const Foo *foo); #endif #if defined(BAR) void bar(const Bar *bar); #endif