Hi,


I've created a template mixin which contains a struct definition. The template is meant to be mixed into each module - to provide a little bit of auto generated info in each module - generated at compile time. As soon as I reference the symbols in any context, it starts complaining about conflicts between the two modules.

It doesn't have to be a struct; the conflicts exist whether I define a struct, class, function, or whatever... any symbol.

It is valid to manually define symbols with the same name in different modules, since they each exist in a different scope, so why does a symbol brought in by a mixin conflict?

Even defining the struct as private doesn't help. Any ideas would be most appreciated.


Here's a very simple failing case:


// ModuleA.d
module ModuleA;

import ModuleB;

mixin MixinUsefulStuff;

pragma(msg, "a = ", SomeData.a); // Error: ModuleB.MixinUsefulStuff!().SomeData at ModuleB.d(5) conflicts with ModuleA.MixinUsefulStuff!().SomeData at ModuleB.d(5)


// ModuleB.d
module ModuleB;

mixin template MixinUsefulStuff()
{
	struct SomeData
	{
		enum a = 123;
	}
}

mixin MixinUsefulStuff;

And just this second I found this... but it's a few months old and has no follow up.

http://forum.dlang.org/thread/mailman.1054.1398548687.2763.digitalmars-d-bugs@puremagic.com


On Monday, 6 October 2014 at 12:17:01 UTC, Alice wrote:
> Hi,
>
>
> I've created a template mixin which contains a struct definition. The template is meant to be mixed into each module - to provide a little bit of auto generated info in each module - generated at compile time. As soon as I reference the symbols in any context, it starts complaining about conflicts between the two modules.
>
> It doesn't have to be a struct; the conflicts exist whether I define a struct, class, function, or whatever... any symbol.
>
> It is valid to manually define symbols with the same name in different modules, since they each exist in a different scope, so why does a symbol brought in by a mixin conflict?
>
> Even defining the struct as private doesn't help. Any ideas would be most appreciated.
>
>
> Here's a very simple failing case:
>
>
> // ModuleA.d
> module ModuleA;
>
> import ModuleB;
>
> mixin MixinUsefulStuff;
>
> pragma(msg, "a = ", SomeData.a); // Error: ModuleB.MixinUsefulStuff!().SomeData at ModuleB.d(5) conflicts with ModuleA.MixinUsefulStuff!().SomeData at ModuleB.d(5)
>
>
> // ModuleB.d
> module ModuleB;
>
> mixin template MixinUsefulStuff()
> {
> 	struct SomeData
> 	{
> 		enum a = 123;
> 	}
> }
>
> mixin MixinUsefulStuff;

On Mon, 06 Oct 2014 12:17:00 +0000
Alice via Digitalmars-d-learn <digitalmars-d-learn@puremagic.com> wrote:

the joy of mixin bugs, yeah! it's a bug in compiler: it instantiates mixin in invalid scope. for now you can use string mixins, they are working fine.

you also can use this to fix scoping:

=== ModuleA.d ===

  module ModuleA;
  static import ModuleB;
  mixin ModuleB.MixinUsefulStuff;
  pragma(msg, "a = ", SomeData.a);

btw, do you mind to fill a bugreport?

> btw, do you mind to fill a bugreport?

Okay, will do so once I get home from work. Thanks for the scope tip. Will try that out later too.

On 10/06/2014 05:50 AM, ketmar via Digitalmars-d-learn wrote:
> On Mon, 06 Oct 2014 12:17:00 +0000
> Alice via Digitalmars-d-learn <digitalmars-d-learn@puremagic.com> wrote:
>
> the joy of mixin bugs, yeah! it's a bug in compiler: it instantiates
> mixin in invalid scope. for now you can use string mixins, they are
> working fine.
>
> you also can use this to fix scoping:
>
> === ModuleA.d ===
>
>    module ModuleA;
>    static import ModuleB;
>    mixin ModuleB.MixinUsefulStuff;
>    pragma(msg, "a = ", SomeData.a);
>
> btw, do you mind to fill a bugreport?
>

Another workaround is to mixin into a scope and then bring the names out by alias. Doing the following in both files works:

struct MixinUsefulStuffWrapper
{
    mixin MixinUsefulStuff;
}

alias SomeData = MixinUsefulStuffWrapper.SomeData;

Ali

Thanks for your help guys. The workarounds will do for now.

The bug is here: https://issues.dlang.org/show_bug.cgi?id=13587