In the first version, const_pointer is a non-const variable (so located in .data) holding a pointer to potentially constant data—you can't modify the data through that pointer without a typecast, but the actual location in memory may be mutable. That's why you don't get a segfault when you cast away the const and modify the data—the destination (const_pointer) is not const even though the const-qualified pointer would allow it to be.
In the second case the const_value variable itself is const-qualified and thus located in .rodata, but the pointer itself is not const-qualified so nothing prevents you from attempting to modify the data through that pointer. This is why you get a compiler warning about discarding the 'const' qualifier in the initialization. Since const_value is in .rodata, writing to it through the pointer causes a segfault.
As Sean1708 pointed out, it's more obvious what is going on if you place the 'const' qualifier immediately before the thing it's modifying, which is either the pointer operator or the variable name, never the type itself:
What would something like "const int" even mean on its own, anyway? There is no such thing as a mutable integer. It's the memory location holding the integer which may be either mutable or immutable.
In the second case the const_value variable itself is const-qualified and thus located in .rodata, but the pointer itself is not const-qualified so nothing prevents you from attempting to modify the data through that pointer. This is why you get a compiler warning about discarding the 'const' qualifier in the initialization. Since const_value is in .rodata, writing to it through the pointer causes a segfault.
As Sean1708 pointed out, it's more obvious what is going on if you place the 'const' qualifier immediately before the thing it's modifying, which is either the pointer operator or the variable name, never the type itself:
What would something like "const int" even mean on its own, anyway? There is no such thing as a mutable integer. It's the memory location holding the integer which may be either mutable or immutable.