The only real use I can imagine for something like this is template metaprogramming, as with if-constexpr, to achieve similar goals to std::integer_sequence. Something like,

template<int N>

void foo() { … }

void bar() {

    for constexpr(int i = 0; i < 10; i++) {

        foo<i>();

    }

}

But the semantics wouldn’t quite make sense here.

The paper Christof Meerwald just linked seems a good way to approach this.

From: Std-Proposals <std-proposals-bounces@lists.isocpp.org> On Behalf Of Abdullah Qasim via Std-Proposals
Sent: Sunday, May 1, 2022 03:51 AM
To: Jason McKesson via Std-Proposals <std-proposals@lists.isocpp.org>
Cc: Abdullah Qasim <iamminecraftredstoner@outlook.com>
Subject: [std-proposals] constexpr loops

for constexpr ()
for consteval ()
 
while constexpr ()
while consteval ()
 
do constexpr {} while ()
do consteval {} while ()
 
example:
 
for consteval (int i{ 0 }; i < 1’000’000; ++i) {
    cout << "LOL”;
}

Runtime speed is FAST, w/ these loops.

Easy to implement, too.