https://issues.dlang.org/show_bug.cgi?id=23598

Iain Buclaw <ibuclaw@gdcproject.org> changed:

           What    |Removed                     |Added
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                 CC|                            |ibuclaw@gdcproject.org
           See Also|                            |https://issues.dlang.org/sh
                   |                            |ow_bug.cgi?id=23595

--- Comment #1 from Iain Buclaw <ibuclaw@gdcproject.org> ---
Related to issue 23595, and a WIP patch I have in the works fixes this test case too.

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https://issues.dlang.org/show_bug.cgi?id=23598

--- Comment #2 from Max Samukha <maxsamukha@gmail.com> ---
(In reply to Iain Buclaw from comment #1)
> Related to issue 23595, and a WIP patch I have in the works fixes this test case too.

Great! Thanks!

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https://issues.dlang.org/show_bug.cgi?id=23598

Dlang Bot <dlang-bot@dlang.rocks> changed:

           What    |Removed                     |Added
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           Keywords|                            |pull

--- Comment #3 from Dlang Bot <dlang-bot@dlang.rocks> ---
@ibuclaw created dlang/dmd pull request #14826 "dmd.aggregate: Define importAll override for AggregateDeclaration" fixing this issue:

- fix Issue 23598 - Another nasty forward reference bug

https://github.com/dlang/dmd/pull/14826

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https://issues.dlang.org/show_bug.cgi?id=23598

Walter Bright <bugzilla@digitalmars.com> changed:

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                 CC|                            |bugzilla@digitalmars.com

--- Comment #4 from Walter Bright <bugzilla@digitalmars.com> ---
Doing a shrink on the test case:

  alias aliases(a...) = a;

  template sort(alias f, a...) {
    static if (a.length > 0) {
        alias x = f!(a[0]);
        alias sort = a;
    }
    else
        alias sort = a;
  }

  alias SortedItems = sort!(isDependencyOf, String);

  enum isDependencyOf(Item) = Item.DirectDependencies.length == 0;

  struct String {
    alias DirectDependencies = aliases!();
    enum l = SortedItems.length; // no property `length`
  }

If SortedItems is moved last, it compiles successfully.

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https://issues.dlang.org/show_bug.cgi?id=23598

--- Comment #5 from Walter Bright <bugzilla@digitalmars.com> ---
I suspect that when the sort template is instantiated, it is too eager to evaluate its arguments. It should just go as far as seeing String is a struct, and not attempt to semantic its contents.

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https://issues.dlang.org/show_bug.cgi?id=23598

--- Comment #6 from Walter Bright <bugzilla@digitalmars.com> ---
What seems to be happening is the first time it goes through `template sort`, it cannot set `aliasdecl` because the two `alias sort` assignments are hidden behind conditional compilation.

Hence `aliasdecl` is null.

So, in semantic for `struct String` it encounters `SortedItems.length`. The `aliasdecl` is null, so `SortedItems` becomes `sort!(...)` which becomes `void` and there is no `length` for `void`.

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https://issues.dlang.org/show_bug.cgi?id=23598

--- Comment #7 from Walter Bright <bugzilla@digitalmars.com> ---
Perhaps I can make this work by noticing if the `static if` member is the only member of the template, so it can be eagerly evaluated?

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https://issues.dlang.org/show_bug.cgi?id=23598

--- Comment #8 from Walter Bright <bugzilla@digitalmars.com> ---
Looking at expandMembers, perhaps this could be done in two passes - once for the top level conditional compilation, then check oneMember, then again for the rest.

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https://issues.dlang.org/show_bug.cgi?id=23598

Iain Buclaw <ibuclaw@gdcproject.org> changed:

           What    |Removed                     |Added
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           See Also|                            |https://issues.dlang.org/sh
                   |                            |ow_bug.cgi?id=10616,
                   |                            |https://issues.dlang.org/sh
                   |                            |ow_bug.cgi?id=20913,
                   |                            |https://issues.dlang.org/sh
                   |                            |ow_bug.cgi?id=22981

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https://issues.dlang.org/show_bug.cgi?id=23598

Max Samukha <maxsamukha@gmail.com> changed:

           What    |Removed                     |Added
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           Severity|blocker                     |normal

--- Comment #9 from Max Samukha <maxsamukha@gmail.com> ---
(In reply to Walter Bright from comment #8)
> Looking at expandMembers, perhaps this could be done in two passes - once for the top level conditional compilation, then check oneMember, then again for the rest.

I guess doing this won't solve the general problem. Perhaps, I should humble myself and resort to other means instead of trying to get from the compiler what it can't give.

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