How does the compiler determine which overloaded function to call during program compilation?

The compiler selects the overloaded function at compile time based on analyzing the function signatures and the types of arguments passed during the call. The process involves several steps:

1. Finding all functions with the required name — the compiler gathers all function variants with this name.
2. Selecting suitable candidates — functions whose parameters cannot be converted to the argument types are discarded.
3. Determining the best match — among the candidates, the function with the minimal and most precise type conversions of arguments is chosen (for example, preferring exact type matches, then implicit conversions).

If the compiler cannot unambiguously select a single function (for example, if multiple candidates are equally suitable), an ambiguity error occurs.

Example:

void func(int x) {}
void func(double x) {}

func(10);    // calls func(int), as it is an exact match
func(10.5);  // calls func(double)