Re: [PATCH] bitmap: Allow bitmap type to be forward declared

[David Gibson <david@gibson.dropbear.id.au>]

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On Mon, Oct 21, 2019 at 03:09:20PM +0000, Kirill Smelkov wrote:
> Currently bitmap type is defined via untagged struct which makes it
> impossible to forward declare it. Forward-declaring is useful since all
> bitmap functions only use bitmap* and in public user-visible
> headers/datastructures it is enough to indicate that a data field with
> bitmap pointer is there, whereas bitmap.h can be included only in
> implementation.
> 
> Beside that some headers are included by both C and C++ parts of a
> project, and when ccan/bitmap.h is processed by C++ compiler it gives:
> 
>     ./3rdparty/ccan/ccan/bitmap/bitmap.h: In function ‘bitmap* bitmap_alloc(long unsigned int)’:
>     ./3rdparty/ccan/ccan/bitmap/bitmap.h:201:15: error: invalid conversion from ‘void*’ to ‘bitmap*’ [-fpermissive]
>       return malloc(bitmap_sizeof(nbits));
>              ~~~~~~^~~~~~~~~~~~~~~~~~~~~~
>     ./3rdparty/ccan/ccan/bitmap/bitmap.h: In function ‘bitmap* bitmap_realloc0(bitmap*, long unsigned int, long unsigned int)’:
>     ./3rdparty/ccan/ccan/bitmap/bitmap.h:227:18: error: invalid conversion from ‘void*’ to ‘bitmap*’ [-fpermissive]
>       bitmap = realloc(bitmap, bitmap_sizeof(nbits));
>                ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
>     ./3rdparty/ccan/ccan/bitmap/bitmap.h: In function ‘bitmap* bitmap_realloc1(bitmap*, long unsigned int, long unsigned int)’:
>     ./3rdparty/ccan/ccan/bitmap/bitmap.h:238:18: error: invalid conversion from ‘void*’ to ‘bitmap*’ [-fpermissive]
>       bitmap = realloc(bitmap, bitmap_sizeof(nbits));
> 
> -> Give to users ability not to force-include ccan/bitmap.h by
> forward-declaring bitmaps like this:
> 
>     typedef struct bitmap bitmap;
>     ...
>     struct MyStruct {
>         bitmap *my_bitmap;
>     };
> 
> Cc: David Gibson <david@gibson.dropbear.id.au>
> Signed-off-by: Kirill Smelkov <kirr@nexedi.com>

Applied, thanks.

> ---
>  ccan/bitmap/bitmap.h | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/ccan/bitmap/bitmap.h b/ccan/bitmap/bitmap.h
> index beeb1e95..54382801 100644
> --- a/ccan/bitmap/bitmap.h
> +++ b/ccan/bitmap/bitmap.h
> @@ -21,7 +21,7 @@ typedef unsigned long bitmap_word;
>  /*
>   * We wrap each word in a structure for type checking.
>   */
> -typedef struct {
> +typedef struct bitmap {
>  	bitmap_word w;
>  } bitmap;
> 

-- 
David Gibson			| I'll have my music baroque, and my code
david AT gibson.dropbear.id.au	| minimalist, thank you.  NOT _the_ _other_
				| _way_ _around_!
http://www.ozlabs.org/~dgibson

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