A call to an overloaded function can be ambiguous if the function has multiple versions (overloads) with similar or identical parameter lists. In this case, the compiler may not be able to determine which version of the function to call based on the arguments passed to the function.

For example, consider the following function overloads:

void foo(int x) { /* code goes here / }
void foo(double x) { / code goes here */ }

If we call the foo function with an argument of type float, the compiler cannot determine which version of the function to call, as the float type can be implicitly converted to either int or double. This results in an ambiguity error.

To avoid ambiguity errors, it is important to provide enough information for the compiler to determine which version of the function to call. This can be done by using explicit type conversion, or by ensuring that the function overloads have distinct parameter lists.