Jeff King [off-list ref] writes:

The previous patch added a coccinelle rule to make sure callers always
use git_hash_init() rather than direct function pointers from the algo
struct.

Let's do the same for the rest of the git_hash_*() wrappers. I split
these out because they're a bit different: they implicitly use the algop
pointer in the git_hash_ctx. So when we convert:

  -algo->update_fn(&ctx, buf, len);
  +git_hash_update(&ctx, buf, len);

we drop the reference to algo entirely! But this is always going to be
the right thing. If "algo" does not match what is in ctx.algop, then
we'd already be invoking undefined behavior.

So in addition to making it possible to add more logic to the
git_hash_*() functions, we're avoiding the need to pass around the extra
algo pointer and make sure that it matches what's in "ctx".

The rest of the patch is the mechanical application of that coccinelle
patch, plus a minor cleanup in test-synthesize.c to drop a now-unused
function parameter (since we don't have to pass around the algo
separately anymore).

Signed-off-by: Jeff King <redacted>
---
 builtin/submodule--helper.c |  8 +++---
 t/helper/test-synthesize.c  | 29 ++++++++++----------
 tools/coccinelle/hash.cocci | 53 +++++++++++++++++++++++++++++++++++++
 3 files changed, 71 insertions(+), 19 deletions(-)

Looks very straight-forward.