[Issue 22006] New: static foreach and foreach over tuple doesn't work on 16-bit

[d-bugmail at puremagic.com]

https://issues.dlang.org/show_bug.cgi?id=22006

          Issue ID: 22006
           Summary: static foreach and foreach over tuple doesn't work on
                    16-bit
           Product: D
           Version: D2
          Hardware: All
                OS: All
            Status: NEW
          Severity: major
          Priority: P1
         Component: dmd
          Assignee: nobody at puremagic.com
          Reporter: ibuclaw at gdcproject.org

Despite `size_t` being a 16-bit foreach complains when the index type is a
non-int, non-long type.

i.e:
```
alias AliasSeq(TList...) = TList;
alias size_t = ushort;

void foo(int a, int b, int c)
{
    foreach (size_t i, e; [0, 1, 2, 3]) { } // OK

    static foreach (size_t i, e; [0, 1, 2, 3]) { } // Error

    foreach (size_t i, e; AliasSeq!(0, 1, 2, 3)) { } // Error
}
```

Because the length of tuples are known at compile-time, there should be no
reason that the same logic as static arrays isn't applied here too.

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