Remove redundant attributes

[9rnsr]

Required by: dlang/dmd#3696

[monarchdodra]

Wasn't this meant to be inout(T)* ? Your change seems to have flagged an issue?

[9rnsr]

I don't know the intention of first author, but currently @property inout T* peek(T)() inout is exactly same with @property T* peek(T)() inout. So this PR changes nothing.

[9rnsr]

Note that, the return statements in function body now return T*.

[schveiguy]

Those returns ALSO have casts. It's pretty obvious that the casts should be removed. An immutable or const Variant should not return a mutable reference to itself.

This incorrectly compiles and runs without error with the existing compiler, and likely with your changes as well:

import std.variant;

void main()
{
    immutable v = Variant(5);
    assert(v == 5);
    auto p = v.peek!int();
    assert(p);
    *p = 4;
    assert(v == 4);
}

Note: Variant really has no good support for being const or immutable, so I'm not even sure why it has any inout support anyway. I couldn't even print or get the value except (ironically) via peek.

[monarchdodra]

OK, so it seems the code used to (incorrectly) compile because there was a cast. If I'm not mistaken, the code can be fixed, by simply removing the cast, and returning the correct inout type.

@9rnsr : Would you mind making the fix? I realize you just wanted 3696 to pass, but (AFAIK) the intent of 3696 was specifically to catch these kinds of issues...

[schveiguy]

I'm not sure it's relevant to this PR, at least for std.variant.Variant. It looks like the type is quite unusable as const or immutable, not sure why the peek function was annotated as inout.

I'm inclined to say, let's pull this, and fix the annotation issues in a separate bug/pull.

Edit, not annotation issues, but the cast issues.

[monarchdodra]

I'm inclined to say, let's pull this, and fix the annotation issues in a separate bug/pull.

Alright, works for me. Let's just not forget about them then.

[schveiguy]

Issue 13000

[9rnsr]

Thanks for merging. and I confirmed the issue. To fix it, I opened #2279.