Re: [PATCHv3 2/3] patch-ids.c: use hashmap correctly

> As eluded to in the previous patch, the code in patch-ids.c is using
> the hashmaps API wrong.
>
> Luckily we do not have a bug, as all hashmap functionality that we use
> here (hashmap_get) passes through the keydata.  If hashmap_get_next were
> to be used, a bug would occur as that passes NULL for the key_data.
>
> So instead use the hashmap API correctly and provide the caller required
> data in the compare function via the first argument that always gets
> passed and was setup via the hashmap_init function.
>
> Signed-off-by: Stefan Beller <sbeller@google.com>
> ---
>  patch-ids.c | 8 ++++----
>  1 file changed, 4 insertions(+), 4 deletions(-)

>
> diff --git a/patch-ids.c b/patch-ids.c
> index 815c115811..b4166b0f38 100644
> --- a/patch-ids.c
> +++ b/patch-ids.c
> @@ -35,10 +35,10 @@ int commit_patch_id(struct commit *commit, struct diff_options *options,
>   * the side of safety.  The actual value being negative does not have
>   * any significance; only that it is non-zero matters.
>   */
> -static int patch_id_cmp(const void *unused_cmp_data,
> +static int patch_id_cmp(struct diff_options *opt,
>  			struct patch_id *a,
>  			struct patch_id *b,
> -			struct diff_options *opt)
> +			const void *unused_keydata)
>  {
>  	if (is_null_oid(&a->patch_id) &&
>  	    commit_patch_id(a->commit, opt, &a->patch_id, 0))
> @@ -59,7 +59,7 @@ int init_patch_ids(struct patch_ids *ids)
>  	DIFF_OPT_SET(&ids->diffopts, RECURSIVE);
>  	diff_setup_done(&ids->diffopts);
>  	hashmap_init(&ids->patches, (hashmap_cmp_fn)patch_id_cmp,
> -		     NULL, 256);
> +		     &ids->diffopts, 256);
>  	return 0;
>  }
>  
> @@ -95,7 +95,7 @@ struct patch_id *has_commit_patch_id(struct commit *commit,
>  	if (init_patch_id_entry(&patch, commit, ids))
>  		return NULL;
>  
> -	return hashmap_get(&ids->patches, &patch, &ids->diffopts);
> +	return hashmap_get(&ids->patches, &patch, NULL);
>  }
>  
>  struct patch_id *add_commit_patch_id(struct commit *commit,