By default, pass pointers and references to `const`s

Reason

To avoid a called function unexpectedly changing the value. It's far easier to reason about programs when called functions don't modify state.

Example

void f(char* p);        // does f modify *p? (assume it does)
void g(const char* p);  // g does not modify *p

Note

It is not inherently bad to pass a pointer or reference to non-const, but that should be done only when the called function is supposed to modify the object.

Note

Do not cast away const.

Enforcement

• Flag a function that does not modify an object passed by pointer or reference to non-const
• Flag a function that (using a cast) modifies an object passed by pointer or reference to const