Re: [PATCH 02/12] hash: create union for hash context allocation

> In various parts of our code, we want to allocate a structure
> representing the internal state of a hash algorithm.  The original
> implementation of the hash algorithm abstraction assumed we would do
> that using heap allocations, and added a context size element to struct
> git_hash_algo.  However, most of the existing code uses stack
> allocations and conversion would needlessly complicate various parts of
> the code.  Add a union for the purpose of allocating hash contexts on
> the stack and a typedef for ease of use.  Remove the ctxsz element for
> struct git_hash_algo, which is no longer very useful.

> +/* A suitably aligned type for stack allocations of hash contexts. */
> +union git_hash_ctx {
> +	git_SHA_CTX sha1;
> +};
> +typedef union git_hash_ctx git_hash_ctx;
> +
>   typedef void (*git_hash_init_fn)(void *ctx);
>   typedef void (*git_hash_update_fn)(void *ctx, const void *in, size_t len);
>   typedef void (*git_hash_final_fn)(unsigned char *hash, void *ctx);