[RESOLVED] Why g++ fails to find correct overload in this case?

[superbonzo]

but the signatures of foo::write_binary and global write_binary are different
so the compiler must be able to choose correct function

the write_binary name in the class declarative scope hides the global write_binary name; in general, the compiler will traverse the "scope tree" from leaf to nodes and it will stop as soon as a node has been fully traversed and a set of candidate names has been found. The actual (function,varaible,whatever) name is picked from that set only.

For example, in the code

void f(int x);

struct A { void f() { f(1); } };

at the point of f(1) call there's an "f" name in the class scope. The set of candidates for overload resolution becomes {A::f()}. Therefore a compiler error is raised.

Indeed, the same thing happens with variables:

class A{ public: A(int x){ x=x; } private: int x; }

will not set the member variable x to the expected argument value ( but A(int x):x(x){} will do )