[Issue 12433] Allow forward referencing IFTI types in template argument list

[via Digitalmars-d-bugs]

https://issues.dlang.org/show_bug.cgi?id=12433

greensunny12 at gmail.com changed:

           What    |Removed                     |Added
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                 CC|                            |greensunny12 at gmail.com

--- Comment #2 from greensunny12 at gmail.com ---
It's not an "hypothetical example" - it makes real code ugly! :/

Let me add an example from a recent PR in phobos
https://github.com/dlang/phobos/pull/4263

If we could support the forwarding of argument types, we would only have _one_,
very nice & readable function header:


```
T[] makeArray(T = Unqual!(ElementType!R), Allocator, R)
```


Of course we can add another function overload, but it unnecessary bloats!

```
Unqual!(ElementType!R)[] makeArray(Allocator, R)(auto ref Allocator alloc, R
range)
{
      import std.range.primitives;
      alias T = Unqual!(ElementType!R);
      return makeArray!(T, Allocator, R)(alloc, range);
}

T[] makeArray(T, Allocator, R)(auto ref Allocator alloc, R range)      
```

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