Constant HDC objects can be modified indirectly (may result in undefined behaviour) #3
Description
A function accepting a const HDC object can (accidentally) cast away const-ness as in the following example program.
#include <hdc.hpp>
void manipulate_const_hdc(HDC const &in) {
HDC copy = in;
copy["new member"] = 1;
}
int main() {
HDC test;
test["only member"] = 1;
test.dump();
manipulate_const_hdc(test);
test.dump();
return 0;
}Expected behaviour:
The function manipulate_const_hdc gets a constant reference to a HDC object. It shouldn't be able to alter this object as doing so results in undefined behavior, see cppreference.com:
- A const object is
- an object whose type is const-qualified, or
- a non-mutable subobject of a const object.
Such object cannot be modified: attempt to do so directly is a compile-time error, and attempt to do so indirectly (e.g., by modifying the const object through a reference or pointer to non-const type) results in undefined behavior.
The copy assignment HDC copy = in; should either be prohibited, or it should create a (deep) copy of the HDC object such that the assignment copy["new member"] = 1; doesn't influence the original HDC object.
Actual behaviour:
Output of above test program:
{
"only member" : 1
}
{
"new member" : 1,
"only member" : 1
}
Used version of the HDC library: 0.21.0