Why can't a constexpr "variable" be seen only by a capturing lambda?

Question

Why can't a constexpr "variable" be seen only by a capturing lambda ? For me the a constexpr "variable" should have the same meaning as a static const "variable"; and the latter one can be seen inside a lambda without any capturing.

Maybe stackoverflow.com/questions/33873788/… would answer your question ? — Laurent Jospin
– Laurent Jospin, Commented Mar 16, 2022 at 7:54

Klaus · Accepted Answer · 2022-03-16 08:10:46Z

2

As the already linked answer is pretty old, I take the example code from here and it compiles now fine with clang, gcc. MSVC still rejects the code, however. Seems to be a compiler bug.

#include<array>
int main()
{
    constexpr int i = 0; 
    auto f = []{
        std::array<int, i> a;
    };   
    return 0;
}

see on godbolt

That gcc and clang is right can be read lambda capture here:

captures: A lambda expression can read the value of a variable without capturing it if the variable :

is constexpr and has no mutable members.

answered Mar 16, 2022 at 8:10

Klaus

26k9 gold badges66 silver badges135 bronze badges

Sign up to request clarification or add additional context in comments.

1 Comment

user20575107 Dec 4, 2024 at 6:37

Collectives™ on Stack Overflow

Why can't a constexpr "variable" be seen only by a capturing lambda?

1 Answer 1

1 Comment

Your Answer

Linked

Hot Network Questions

Collectives™ on Stack Overflow

1 Answer 1

1 Comment

Your Answer

Sign up or log in

Post as a guest

Linked

Related