Does providing an explicit deduction guide disable the generation/formation of implicit deduction guides

Question

I am reading about deduction guides in C++17. So say we have the following example:

template<typename T> struct Custom 
{
  
};
template<typename T> struct Person 
{
    Person(Custom<T> const&);
    Person(Custom<T>&&);
};
template<typename T> Person(Custom<T>) -> Person<T>; //explicitly declared deduction guide

My question is that will the explicit declaration for the explicit deduction guide(as shown above) disable the formation of the 2 implicit deduction guides(corresponding to the 2 ctors of class template Person) that would have been there if we did not specify an explicit deduction guide. I mean, suppose in the above example, there was no explicit deduction guide, then there will be 2 implicit deduction guides(corresponding to the two constructors of Person). But after we have added explicit guide, will we have a total of 1 deduction guide(explicitly declared by us the user) or 3 deduction guides(including 2 implicit deduction guides).

PS: Note that the question is only about the deduction guides for Person and not about whether implicit guide will be formed for Custom.

Answer 1

No, deduction-guide declarations do not suppress the formation of implicit deduction guides during the class template argument deduction process. The overload set will contain both. See [over.match.class.deduct]/1:

... a set of functions and function templates, called the guides of C, is formed comprising:

• If C is defined, for each constructor of C, a function template with the following properties: ...
• If C is not defined or does not declare any constructors, an additional function template derived as above from a hypothetical constructor C().
• An additional function template derived as above from a hypothetical constructor C(C), called the copy deduction candidate.
• For each deduction-guide, a function or function template with the following properties: ...

[additional provisions related to aggregates omitted...]

However, the third last tiebreaker in the overload resolution process gives precedence to deduction-guides (i.e., explicitly declared deduction guides) over implicit deduction guides. [over.match.best.general]/2.10. This tiebreaker is only reached after all of the more general tiebreakers (not related directly to deduction guides) are tried.