digitalmars.D - Dynamic array of pointers to opaque structs

Johan F. (33/33) Jun 05 2013 I'm fiddling around with SDL2 using Derelict3, and I'm trying to

Timon Gehr (3/34) Jun 05 2013 It is a compiler bug, but we cannot confirm it unless you provide a

Johan F. (10/67) Jun 05 2013 This triggers it (2.063):

Adam D. Ruppe (9/12) Jun 05 2013 Just guessing here, what happens if you make that

Johan F. (3/15) Jun 05 2013 Ok, thanks. I'll just add {} then, until the bug(?) gets fixed.

Namespace (2/2) Jun 05 2013 It's not a bug:

Johan F. (4/6) Jun 05 2013 Hmm, that thread seems to address something else? I'm talking

Namespace (1/1) Jun 05 2013 Oh ok. I thought you suspect a bug in Derelict.

Mike Parker (5/38) Aug 28 2013 For anyone stumbling across this thread in the future, there's a

"Johan F." <jaffe1 gmail.com> writes:

I'm fiddling around with SDL2 using Derelict3, and I'm trying to 
make an array of SDL_Texture pointers, like so:

     SDL_Texture*[] frames;
     ... make texture ...
     frames ~= texture;

However, this yields the following error:

/Users/jaffe1/prog/Derelict3/import/derelict/sdl2/types.d(1865): 
Error: struct derelict.sdl2.types.SDL_Texture is forward 
referenced when looking for 'toHash'
/Users/jaffe1/prog/Derelict3/import/derelict/sdl2/types.d(1865): 
Error: struct derelict.sdl2.types.SDL_Texture is forward 
referenced when looking for 'opCmp'
/Users/jaffe1/prog/Derelict3/import/derelict/sdl2/types.d(1865): 
Error: struct derelict.sdl2.types.SDL_Texture is forward 
referenced when looking for 'toString'
/Users/jaffe1/prog/Derelict3/import/derelict/sdl2/types.d(1865): 
Error: struct derelict.sdl2.types.SDL_Texture unknown size
/Users/jaffe1/prog/Derelict3/import/derelict/sdl2/types.d(1865): 
Error: struct derelict.sdl2.types.SDL_Texture no size yet for 
forward reference
/Users/jaffe1/prog/Derelict3/import/derelict/sdl2/types.d(1865): 
Error: struct derelict.sdl2.types.SDL_Texture unknown size
/Users/jaffe1/prog/Derelict3/import/derelict/sdl2/types.d(1865): 
Error: struct derelict.sdl2.types.SDL_Texture no size yet for 
forward reference

At line 1865 in types.d is the opaque struct declaration

     struct SDL_Texture;

The program compiles and works fine if I change this line to

     struct SDL_Texture {};

This seems weird to me. Why is making an array of _pointers_ to 
SDL_Texture dependant on how the SDL_Texture struct is declared? 
Also, is simply adding {} the right way of fixing it, or will 
that possibly break something else?

Jun 05 2013

Timon Gehr <timon.gehr gmx.ch> writes:

On 06/05/2013 10:34 PM, Johan F. wrote:
 I'm fiddling around with SDL2 using Derelict3, and I'm trying to make an
 array of SDL_Texture pointers, like so:

      SDL_Texture*[] frames;
      ... make texture ...
      frames ~= texture;

 However, this yields the following error:

 /Users/jaffe1/prog/Derelict3/import/derelict/sdl2/types.d(1865): Error:
 struct derelict.sdl2.types.SDL_Texture is forward referenced when
 looking for 'toHash'
 /Users/jaffe1/prog/Derelict3/import/derelict/sdl2/types.d(1865): Error:
 struct derelict.sdl2.types.SDL_Texture is forward referenced when
 looking for 'opCmp'
 /Users/jaffe1/prog/Derelict3/import/derelict/sdl2/types.d(1865): Error:
 struct derelict.sdl2.types.SDL_Texture is forward referenced when
 looking for 'toString'
 /Users/jaffe1/prog/Derelict3/import/derelict/sdl2/types.d(1865): Error:
 struct derelict.sdl2.types.SDL_Texture unknown size
 /Users/jaffe1/prog/Derelict3/import/derelict/sdl2/types.d(1865): Error:
 struct derelict.sdl2.types.SDL_Texture no size yet for forward reference
 /Users/jaffe1/prog/Derelict3/import/derelict/sdl2/types.d(1865): Error:
 struct derelict.sdl2.types.SDL_Texture unknown size
 /Users/jaffe1/prog/Derelict3/import/derelict/sdl2/types.d(1865): Error:
 struct derelict.sdl2.types.SDL_Texture no size yet for forward reference

 At line 1865 in types.d is the opaque struct declaration

      struct SDL_Texture;

 The program compiles and works fine if I change this line to

      struct SDL_Texture {};

 This seems weird to me. Why is making an array of _pointers_ to
 SDL_Texture dependant on how the SDL_Texture struct is declared? Also,
 is simply adding {} the right way of fixing it, or will that possibly
 break something else?

It is a compiler bug, but we cannot confirm it unless you provide a 
minimal example that triggers it.

Jun 05 2013

"Johan F." <jaffe1 gmail.com> writes:

On Wednesday, 5 June 2013 at 20:37:27 UTC, Timon Gehr wrote:
 On 06/05/2013 10:34 PM, Johan F. wrote:
 I'm fiddling around with SDL2 using Derelict3, and I'm trying 
 to make an
 array of SDL_Texture pointers, like so:

     SDL_Texture*[] frames;
     ... make texture ...
     frames ~= texture;

 However, this yields the following error:

 /Users/jaffe1/prog/Derelict3/import/derelict/sdl2/types.d(1865): 
 Error:
 struct derelict.sdl2.types.SDL_Texture is forward referenced 
 when
 looking for 'toHash'
 /Users/jaffe1/prog/Derelict3/import/derelict/sdl2/types.d(1865): 
 Error:
 struct derelict.sdl2.types.SDL_Texture is forward referenced 
 when
 looking for 'opCmp'
 /Users/jaffe1/prog/Derelict3/import/derelict/sdl2/types.d(1865): 
 Error:
 struct derelict.sdl2.types.SDL_Texture is forward referenced 
 when
 looking for 'toString'
 /Users/jaffe1/prog/Derelict3/import/derelict/sdl2/types.d(1865): 
 Error:
 struct derelict.sdl2.types.SDL_Texture unknown size
 /Users/jaffe1/prog/Derelict3/import/derelict/sdl2/types.d(1865): 
 Error:
 struct derelict.sdl2.types.SDL_Texture no size yet for forward 
 reference
 /Users/jaffe1/prog/Derelict3/import/derelict/sdl2/types.d(1865): 
 Error:
 struct derelict.sdl2.types.SDL_Texture unknown size
 /Users/jaffe1/prog/Derelict3/import/derelict/sdl2/types.d(1865): 
 Error:
 struct derelict.sdl2.types.SDL_Texture no size yet for forward 
 reference

 At line 1865 in types.d is the opaque struct declaration

     struct SDL_Texture;

 The program compiles and works fine if I change this line to

     struct SDL_Texture {};

 This seems weird to me. Why is making an array of _pointers_ to
 SDL_Texture dependant on how the SDL_Texture struct is 
 declared? Also,
 is simply adding {} the right way of fixing it, or will that 
 possibly
 break something else?

 It is a compiler bug, but we cannot confirm it unless you 
 provide a minimal example that triggers it.

This triggers it (2.063):

     struct something;

     int main()
     {
         something*[] stuff;
         something* a;
         stuff ~= a;
         return 0;
     }

Jun 05 2013

"Adam D. Ruppe" <destructionator gmail.com> writes:

On Wednesday, 5 June 2013 at 20:34:17 UTC, Johan F. wrote:
     struct SDL_Texture;

Just guessing here, what happens if you make that

extern(C) struct SDL_Texture;

?

 Also, is simply adding {} the right way of fixing it, or will 
 that possibly break something else?

This shouldn't break anything since it is just adding RTTI info 
to D (opCmp, toHash, etc, are members of the D TypeInfo for this 
struct. why they are required in this case is beyond me). It 
doesn't change the actual core of the code, which are still just 
pointers.

Jun 05 2013

"Johan F." <jaffe1 gmail.com> writes:

On Wednesday, 5 June 2013 at 20:38:08 UTC, Adam D. Ruppe wrote:
 On Wednesday, 5 June 2013 at 20:34:17 UTC, Johan F. wrote:
    struct SDL_Texture;

 Just guessing here, what happens if you make that

 extern(C) struct SDL_Texture;

 ?

It doesn't change anything.

 Also, is simply adding {} the right way of fixing it, or will 
 that possibly break something else?

 This shouldn't break anything since it is just adding RTTI info 
 to D (opCmp, toHash, etc, are members of the D TypeInfo for 
 this struct. why they are required in this case is beyond me). 
 It doesn't change the actual core of the code, which are still 
 just pointers.

Ok, thanks. I'll just add {} then, until the bug(?) gets fixed.

Jun 05 2013

"Namespace" <rswhite4 googlemail.com> writes:

It's not a bug:
http://dblog.aldacron.net/forum/index.php?topic=820.0

Jun 05 2013

"Johan F." <jaffe1 gmail.com> writes:

On Wednesday, 5 June 2013 at 20:51:03 UTC, Namespace wrote:
 It's not a bug:
 http://dblog.aldacron.net/forum/index.php?topic=820.0

Hmm, that thread seems to address something else? I'm talking 
about simply making an array of pointers to opaque structs, which

Jun 05 2013

"Namespace" <rswhite4 googlemail.com> writes:

Oh ok. I thought you suspect a bug in Derelict.

Jun 05 2013

"Mike Parker" <aldacron gmail.com> writes:

On Wednesday, 5 June 2013 at 20:34:17 UTC, Johan F. wrote:
 I'm fiddling around with SDL2 using Derelict3, and I'm trying 
 to make an array of SDL_Texture pointers, like so:

     SDL_Texture*[] frames;
     ... make texture ...
     frames ~= texture;

 However, this yields the following error:

 /Users/jaffe1/prog/Derelict3/import/derelict/sdl2/types.d(1865): 
 Error: struct derelict.sdl2.types.SDL_Texture is forward 
 referenced when looking for 'toHash'
 /Users/jaffe1/prog/Derelict3/import/derelict/sdl2/types.d(1865): 
 Error: struct derelict.sdl2.types.SDL_Texture is forward 
 referenced when looking for 'opCmp'
 /Users/jaffe1/prog/Derelict3/import/derelict/sdl2/types.d(1865): 
 Error: struct derelict.sdl2.types.SDL_Texture is forward 
 referenced when looking for 'toString'
 /Users/jaffe1/prog/Derelict3/import/derelict/sdl2/types.d(1865): 
 Error: struct derelict.sdl2.types.SDL_Texture unknown size
 /Users/jaffe1/prog/Derelict3/import/derelict/sdl2/types.d(1865): 
 Error: struct derelict.sdl2.types.SDL_Texture no size yet for 
 forward reference
 /Users/jaffe1/prog/Derelict3/import/derelict/sdl2/types.d(1865): 
 Error: struct derelict.sdl2.types.SDL_Texture unknown size
 /Users/jaffe1/prog/Derelict3/import/derelict/sdl2/types.d(1865): 
 Error: struct derelict.sdl2.types.SDL_Texture no size yet for 
 forward reference

 At line 1865 in types.d is the opaque struct declaration

     struct SDL_Texture;

 The program compiles and works fine if I change this line to

     struct SDL_Texture {};

 This seems weird to me. Why is making an array of _pointers_ to 
 SDL_Texture dependant on how the SDL_Texture struct is 
 declared? Also, is simply adding {} the right way of fixing it, 
 or will that possibly break something else?

For anyone stumbling across this thread in the future, there's a 
report for this in bugzilla[1]. It's an issue in the compiler 
with the handling of opaque structs.

[1] http://d.puremagic.com/issues/show_bug.cgi?id=10451

Aug 28 2013

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digitalmars.D - Dynamic array of pointers to opaque structs