Linker Errors when Constructing an Immutable Struct

[Adam Wilson via Digitalmars-d]

On Mon, 02 Jun 2014 00:42:07 -0700, Jonathan M Davis via Digitalmars-d  
<digitalmars-d at puremagic.com> wrote:

> On Mon, 02 Jun 2014 00:13:32 -0700
> Adam Wilson via Digitalmars-d <digitalmars-d at puremagic.com> wrote:
>
>> Please consider the following code:
>>
>> module aurora.immediate.input;
>>
>> public enum Key : int { //... }
>>
>> public immutable struct KeyData
>> {
>>   private Key _key;
>>   @property public Key KeyCode() { return _key; }
>>
>>   private bool _isDown;
>>   @property public bool IsDown() { return _isDown; }
>>
>>   private bool _isUp;
>>   @property public bool IsUp() { return _isUp; }
>>
>>   private bool _isRepeating;
>>   @property public bool IsRepeating() { return _isRepeating; }
>>
>>   @disable this();
>>
>>   public immutable this(Key key, bool isDown, bool isUp, bool
>> isRepeating = false) nothrow
>>   {
>>       _key = key;
>>       _isDown = isDown;
>>       _isUp = isUp;
>>       _isRepeating = isRepeating;
>>   }
>> }
>>
>> module aurora.immediate.window;
>> import aurora.immediate.input;
>>
>> public class Window {
>> protected void delegate(immutable(KeyData) args) nothrow onKeyDown;
>> private LRESULT internalWndProc(HWND hwnd, UINT message, WPARAM
>> wParam, LPARAM lParam) nothrow {
>>   if (onKeyDown !is null) onKeyDown(immutable
>> KeyData(cast(Key)wParam, true, false, false));
>>   return 0;
>> }
>> }
>>
>> When compiled and imported as a static library it fails to compile
>> with the following linker errors:
>> libaurora_immediate64d.lib(window_47a_278.obj) : error LNK2019:
>> unresolved external symbol _D6aurora9immediate5input7KeyData6__initZ
>> referenced in function
>> _D6aurora9immediate6window6Window15internalWndProcMFNbPvkmlZl
>> libaurora_immediate64d.lib(window_47a_278.obj) : error LNK2019:
>> unresolved external symbol
>> _D6aurora9immediate5input7KeyData6__ctorMyFNbNcE6aurora9immediate5input3KeybbbZyS6aurora9immediate5input7KeyData
>> referenced in function
>> _D6aurora9immediate6window6Window15internalWndProcMFNbPvkmlZl
>>
>> It appears that the linker cannot find .init and the .ctor. Is this
>> a compiler bug or am I doing something wrong? I am wondering if this
>> is a problem with immutable structs? Any pointers would be very
>> appreciated.
>>
>
> It's probably a bug, though I'd point out that all it means when you  
> mark a
> struct declaration as immutable is that you've marked all of its members  
> as
> immutable (meaning that marking the constructor as immutable is  
> redundant).
> Also, if all of the member variables are immutable, there really isn't  
> much
> point in declaring getters. You might as well just make them public.
> Regardless, I don't know why you'd be getting the errors that you're  
> getting.
> You could try just marking all of the members as immutable directly and
> removing the getters and seeing if that magically fixes things for you  
> (though
> it probably won't). It does sound like a compiler bug though.
>
> - Jonathan M Davis

Ok, i'll report it then. I've tried the constructor both with and without  
the redundant immutable tag, because sometimes DMD has  
takes-one-but-not-the-other bugs. I actually tried it a bunch of different  
ways, with getters, without getters, with individual immutable, without,  
etc. No dice.

-- 
Adam Wilson
GitHub/IRC: LightBender
Aurora Project Coordinator