Re: [PATCH v4 1/7] Add delta-islands.{c,h}

On Mon, Aug 13, 2018 at 8:11 PM, Jeff King [off-list ref] wrote:

On Mon, Aug 13, 2018 at 01:17:18PM +0100, Ramsay Jones wrote:

quoted

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+struct island_bitmap {
+     uint32_t refcount;
+     uint32_t bits[];

Use FLEX_ARRAY here? We are slowly moving toward requiring
certain C99 features, but I can't remember a flex array
weather-balloon patch.

This was already discussed by Junio and Peff there:

https://public-inbox.org/git/20180727130229.GB18599@sigill.intra.peff.net/

That is a fine discussion, without a firm conclusion, but I don't
think you can simply do nothing here:

  $ cat -n junk.c
       1      #include <stdint.h>
       2
       3      struct island_bitmap {
       4              uint32_t refcount;
       5              uint32_t bits[];
       6      };
       7
  $ gcc --std=c89 --pedantic -c junk.c
  junk.c:5:11: warning: ISO C90 does not support flexible array members [-Wpedantic]
    uint32_t bits[];
             ^~~~
  $ gcc --std=c99 --pedantic -c junk.c

Right, whether we use the FLEX_ALLOC macros or not, this needs to be
declared with FLEX_ARRAY, not an empty "[]".

Ok, it will use FLEX_ARRAY in the reroll I will send soon.

Thanks Ramsay and Peff!