[Bug c++/88628] lambda expression in static_assert in if constexpr is not evaluated

[merukun1125 at docomo dot ne.jp]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=88628

merukun1125 at docomo dot ne.jp changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|UNCONFIRMED                 |RESOLVED
         Resolution|---                         |INVALID

--- Comment #6 from merukun1125 at docomo dot ne.jp ---
(In reply to Jakub Jelinek from comment #4)
> lambda is AFAIK a local class, so you need to instantiate it.  So it is more
> similar to:
> #include <type_traits>
> 
> template<typename T>
> constexpr bool run() { return false; }
> 
> template<typename T>
> T get() {
>     struct S {};
>     if constexpr (std::is_same_v<int, T>) return 0;
>     else static_assert(run <S> (), "Lambda expression is evaluated.");
> }
> 
> int main() {
>     get<int>();
> }
> which also compiles fine (and doesn't compile if you use say int or
> something non-dependent in run template-id).

I'm sorry, I was mistaken.

If a lambda expression is defined as a local class, it becomes as follows:

#include <type_traits>

template<typename T>
T get() {
    struct S {
        auto operator()() const -> decltype(false) {
            return false;
        }
    };
    if constexpr (std::is_same_v<int, T>) return 0;
    else static_assert(S{}(), "Lambda expression is evaluated.");
}

int main() {
    get<int>();
}


This code does not fail to compile　because the compiler seems to need T to
determine the type of S.
https://wandbox.org/permlink/QtGF6wpvPr9rlhQ1

I was misunderstood as follows:

#include <type_traits>

struct S { // A type that does not depend on template parameter T
    auto operator()() const -> decltype(false) {
        return false;
    }
};

template<typename T>
T get() {
    if constexpr (std::is_same_v<int, T>) return 0;
    else static_assert(S{}(), "Lambda expression is evaluated.");
}

int main() {
    get<int>();
}

This code fail to compile.
https://wandbox.org/permlink/628XClL8M3dnkD1Q

If you do not mind, please tell me the place if there is a place where lambda
expressions are defined as local classes in n4659 or n4791.