As far as I know, there is no meaning in pointer-to-const other than it must not be used directly to modify the stored value (if it is you get a compile error). It is always valid from the perspective of language semantics to cast-away the const and modify the pointed-to object, as long as the object is not itself read-only. So, to my knowledge, they could not make any additional assumptions based on pointer-to-const, though they could use it as a hint to look for a possible optimization.