passing ‘const this argument discards qualifiers [-fpermissive]

Question

I have a class Cache which has a function write specified as

bool write(const MemoryAccess &memory_access, CacheLine &cl);

Answer 1

When you call a method via a pointer to an object, this object is implicitly passed to the method as this pointer. c probably has type const Cache*. Since method write is not declared as const, it has non-const this pointer accessible from its body requiring const qualifier of c to be discarded.