Re: [PATCH v3 2/3] sparse-index: add ensure_correct_sparsity function

>  {
> -	int test_env;
> -	if (istate->sparse_index || !istate->cache_nr ||
> -	    !core_apply_sparse_checkout || !core_sparse_checkout_cone)
> +	if (!core_apply_sparse_checkout || !core_sparse_checkout_cone)
>  		return 0;
>  
>  	if (!istate->repo)
>  		istate->repo = the_repository;
>  
>  	if (!(flags & SPARSE_INDEX_MEMORY_ONLY)) {
> +		int test_env;
> +
>  		/*
>  		 * The sparse index is not (yet) integrated with a split index.
>  		 */

>  	if (!istate->sparse_checkout_patterns->use_cone_patterns)
>  		return 0;
>  
> +	return 1;
> +}
> +
> +int convert_to_sparse(struct index_state *istate, int flags)
> +{
> +	/*
> +	 * If the index is already sparse, empty, or otherwise
> +	 * cannot be converted to sparse, do not convert.
> +	 */
> +	if (istate->sparse_index || !istate->cache_nr ||
> +	    !is_sparse_index_allowed(istate, flags))
> +		return 0;

> +void ensure_correct_sparsity(struct index_state *istate)
> +{
> +	/*
> +	 * If the index can be sparse, make it sparse. Otherwise,
> +	 * ensure the index is full.
> +	 */
> +	if (is_sparse_index_allowed(istate, 0))
> +		convert_to_sparse(istate, 0);
> +	else
> +		ensure_full_index(istate);
> +}