Re: Dynamic array of pointers to opaque structs

[Mike Parker]

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