https://issues.dlang.org/show_bug.cgi?id=16521

--- Comment #1 from Mathias Lang <mathias.lang@sociomantic.com> ---
A bit of debugging proved that the following code is generated:

```
[{
enum ulong idx = 0;
uint unused = _param_1;
case idx:
{
assert(unused == args[idx], "Borken compiler");
break JT;
}
}
]
```

Note: Using `ref` results in the program segfaulting because it will then dereference an uninitialized `ref`.

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https://issues.dlang.org/show_bug.cgi?id=16521

Nemanja Boric <4burgos@gmail.com> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |4burgos@gmail.com

--- Comment #2 from Nemanja Boric <4burgos@gmail.com> ---
I hit the same bug today:

```
import std.traits;

struct S
{
    int a, b, c, d, e, f;
}

void main()
{
    S s;

    foreach (name; ["a", "b", "c"])
    {
        switch (name)
        {
            foreach (i, ref field; s.tupleof)
            {
                case __traits(identifier, S.tupleof[i]):
                    field = 0; // s.tupleof[i] = 0; works
                    break;
            }
            default:
                break;
        }
    }
}
```

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https://issues.dlang.org/show_bug.cgi?id=16521

Steven Schveighoffer <schveiguy@yahoo.com> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |schveiguy@yahoo.com

--- Comment #3 from Steven Schveighoffer <schveiguy@yahoo.com> ---
I see the same deprecation warning in my code, but I'm not using the actual tuple value, just the index.

Static foreach would be handy here...

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https://issues.dlang.org/show_bug.cgi?id=16521

Stefan Koch <uplink.coder@gmail.com> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
           Keywords|                            |accepts-invalid
                 CC|                            |uplink.coder@gmail.com

--- Comment #4 from Stefan Koch <uplink.coder@gmail.com> ---
There is no such thing as static foreach.
You are using tuple foreach which will force an unrolled loop.

The provided code should error!

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https://issues.dlang.org/show_bug.cgi?id=16521

Nemanja Boric <4burgos@gmail.com> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
           Keywords|accepts-invalid             |

--- Comment #5 from Nemanja Boric <4burgos@gmail.com> ---
I don't agree that this code should error. This is a well known and common D idiom (simple GH search shows examples in Phobos, such: https://github.com/dlang/phobos/blob/master/std/algorithm/sorting.d#L1101), up to the point that there are also merged switch/foreach loops constructs where the label is applied to switch, so the `break` inside foreach would be considered switch break.

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https://issues.dlang.org/show_bug.cgi?id=16521

--- Comment #6 from Stefan Koch <uplink.coder@gmail.com> ---
Just because something is used in phobos does not it is correct.
this code is highly dubious because it goats people into believing that tuple
foreach actually works.

The right way to do this is to build a string for the switch and mix it in.

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https://issues.dlang.org/show_bug.cgi?id=16521

--- Comment #7 from Nemanja Boric <4burgos@gmail.com> ---
I'm not sure who ever got convinced by this code that `static foreach` works. This is just very helpful and clear approach, and it should grant `static foreach` becoming a real thing, because it is useful.

While that is still not implemented, this code should work, as I see this as a
bug/regression
(https://github.com/rejectedsoftware/vibe.d/blob/6f37e694cc77063769bc4c9a42160627103e8354/web/vibe/web/rest.d#L1367
- yet another example, plus dozens on forums, etc).

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https://issues.dlang.org/show_bug.cgi?id=16521

--- Comment #8 from Steven Schveighoffer <schveiguy@yahoo.com> ---
guys, the static foreach comment was a *wish* for this, not a recommendation to use some already existing thing.

It would be nice to do:

static foreach(idx; 0 .. args.length)

Instead of the goofy "unused" symbol thing. In my code, I'm using Args, not args, so I have no idea why a variable for each tuple item should even need to be created. It might even be a type!

Note that the "deprecation" is what I'm concerned about, as I have only this one way to make my switch statement out of a tuple (sorry Stefan, but string mixin is a *vastly inferior* option compared to this mechanism), and some future version of dmd I worry is going to flag this as an error, even though I never use the variable I didn't want to declare but was forced to.

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https://issues.dlang.org/show_bug.cgi?id=16521

Alex Goltman <alex.goltman@gmail.com> changed:

           What    |Removed                     |Added
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                 CC|                            |alex.goltman@gmail.com

--- Comment #9 from Alex Goltman <alex.goltman@gmail.com> ---
looks like a duplicate of my issue https://issues.dlang.org/show_bug.cgi?id=17218

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https://issues.dlang.org/show_bug.cgi?id=16521

--- Comment #10 from Steven Schveighoffer <schveiguy@yahoo.com> ---
*** Issue 17218 has been marked as a duplicate of this issue. ***

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