Simple question: If change this:
void someMethod();
to
void someMethod() noexcept;
will it break binary compatibility, or does the method signature remain the same?
Does the method signature remain the same ?
Yes. https://en.cppreference.com/w/cpp/language/noexcept_spec :
Functions differing only in their exception specification cannot be overloaded (just like the return type, exception specification is part of function type, but not part of the function signature) (since C++17).
Will it break binary compability ?
Probably not, but standard doesn't guarentee anything (AFAIK).