For c++11-style loops, loop counter logic can be easily implemented. Just
an example below:
"
* for (const int i : vector<int>({1, 2, 3})) {*


* i = 5; // prohibited!!! };*
".

Previously it was discussed on how to do the same for "old-school" loops "*for
(??? int i{}; i < n; ++i)*", while preserving backward compatibility.

It might be something like:
Variant-I: "for (int i{}; i<n; ++i) const"
Variant-II: "for (int i{}; i<n; ++i) -> const i

Variant-I would first require "{" and "}" braces while could be
misinterpreted, we don't explicitly specify which variable (loop external,
or loop counters) is subject to applying const specifier.
Variant-II seems to be quite complex from syntax's point of view.

сб, 15 мар. 2025 г. в 05:06, Marcin Jaczewski via Std-Proposals <
std-proposals_at_[hidden]>:

> pt., 14 mar 2025 o 19:19 Sebastian Wittmeier via Std-Proposals
> <std-proposals_at_[hidden]> napisał(a):
> >
> > Perhaps better something like
> >
> >
> >
> > for (auto e : std::values(someEnum))
> >
> >
>
> More like:
> ```
> template for (constexpr auto e : std::values<someEnum>)
> {
> }
> ```
>
> And probably most fun version would be:
>
> ```
> switch (x)
> {
> template for (constexpr auto e : std::values<decltype(x)>)
> {
> case e: /* logic */ break;
> }
> }
> ```
>
> >
> > the order could be implementation-defined? Or even no guaranteed order.
> >
> >
> > -----Ursprüngliche Nachricht-----
> > Von: Andre Kostur via Std-Proposals <std-proposals_at_[hidden]>
> > Gesendet: Fr 14.03.2025 18:18
> > Betreff: Re: [std-proposals] for loop enhancement
> > An: std-proposals_at_[hidden];
> > CC: Andre Kostur <andre_at_[hidden]>;
> > Re: using enum in for loop.
> >
> > for (auto e: <type>) seems weird (and messes with the grammar). And
> > opens the door to 'for ( auto e : unsigned char )', or 'for (auto e :
> > long)'. Yes, I realize that's not what you're asking for now, but it
> > seems like a natural next step.
> >
> > Also two other clarifications would also need to happen: what about
> > duplicate values, and in what order will that loop across the enum
> > values (recall: one can define an enum in an arbitrary order).
> >
> > On Fri, Mar 14, 2025 at 9:43 AM Filip via Std-Proposals
> > <std-proposals_at_[hidden]> wrote:
> > >
> > > I want to ask for your comments about couple of different for loops
> ideas that I had recently:
> > >
> > > 1. using enum in for loop:
> > > ```
> > > for (auto e : someEnum) {...}
> > > ```
> > >
> > > Since compiler knows the elements of `ENUM` it should be able to
> easily unroll the loop or iterate over the elements of enum.
> > >
> > > 2. Forcing unroll with a keyword and not `#pragma`
> > > ```
> > > inline for ( … )
> > > ```
> > > It could force the unroll like similar construct does in zig.
> > > This syntax already exists and we could probably easily implement it.
> > >
> > > 3. Run loop N times
> > > ```
> > > for ( 5 )
> > > ```
> > > Running for loop N number of times is a common issue e.g. N tries to
> connect to the server.
> > > This way would not pollute the namespace with additional `int i` that
> we frankly don’t use.
> > > --
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> > > Std-Proposals_at_[hidden]
> > > https://lists.isocpp.org/mailman/listinfo.cgi/std-proposals
> > --
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> >
> > --
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