builtin/show-ref: convert to use `reference_get_peeled_oid()`

The git-show-ref(1) command has multiple different modes:

  - It knows to show all references matching a pattern.

  - It knows to list all references that are an exact match to whatever
    the user has provided.

  - It knows to check for reference existence.

The first two commands use mostly the same infrastructure to print the
references via `show_one()`. But while the former mode uses a proper
iterator and thus has a `struct reference` available in its context, the
latter calls `refs_read_ref()` and thus doesn't. Consequently, we cannot
easily use `reference_get_peeled_oid()` to print the peeled value.

Adapt the code so that we manually construct a `struct reference` when
verifying refs. We wouldn't ever have the peeled value available anyway
as we're not using an iterator here, so we can simply plug in the values
we _do_ have.

With this change we now have a `struct reference` available at both
callsites of `show_one()` and can thus pass it, which allows us to use
`reference_get_peeled_oid()` instead of `peel_iterated_oid()`.

Signed-off-by: Patrick Steinhardt <ps@pks.im>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

builtin/show-ref.c

diff --git a/builtin/show-ref.c b/builtin/show-ref.c
index 4803b5e..4d4984e 100644
--- a/builtin/show-ref.c
+++ b/builtin/show-ref.c
@@ -31,31 +31,31 @@ struct show_one_options {
 };
 
 static void show_one(const struct show_one_options *opts,
-		     const char *refname, const struct object_id *oid)
+		     const struct reference *ref)
 {
 	const char *hex;
 	struct object_id peeled;
 
-	if (!odb_has_object(the_repository->objects, oid,
+	if (!odb_has_object(the_repository->objects, ref->oid,
 			    HAS_OBJECT_RECHECK_PACKED | HAS_OBJECT_FETCH_PROMISOR))
-		die("git show-ref: bad ref %s (%s)", refname,
-		    oid_to_hex(oid));
+		die("git show-ref: bad ref %s (%s)", ref->name,
+		    oid_to_hex(ref->oid));
 
 	if (opts->quiet)
 		return;
 
-	hex = repo_find_unique_abbrev(the_repository, oid, opts->abbrev);
+	hex = repo_find_unique_abbrev(the_repository, ref->oid, opts->abbrev);
 	if (opts->hash_only)
 		printf("%s\n", hex);
 	else
-		printf("%s %s\n", hex, refname);
+		printf("%s %s\n", hex, ref->name);
 
 	if (!opts->deref_tags)
 		return;
 
-	if (!peel_iterated_oid(the_repository, oid, &peeled)) {
+	if (!reference_get_peeled_oid(the_repository, ref, &peeled)) {
 		hex = repo_find_unique_abbrev(the_repository, &peeled, opts->abbrev);
-		printf("%s %s^{}\n", hex, refname);
+		printf("%s %s^{}\n", hex, ref->name);
 	}
 }
 
@@ -93,7 +93,7 @@ static int show_ref(const struct reference *ref, void *cbdata)
 match:
 	data->found_match++;
 
-	show_one(data->show_one_opts, ref->name, ref->oid);
+	show_one(data->show_one_opts, ref);
 
 	return 0;
 }
@@ -175,12 +175,18 @@ static int cmd_show_ref__verify(const struct show_one_options *show_one_opts,
 
 		if ((starts_with(*refs, "refs/") || refname_is_safe(*refs)) &&
 		    !refs_read_ref(get_main_ref_store(the_repository), *refs, &oid)) {
-			show_one(show_one_opts, *refs, &oid);
-		}
-		else if (!show_one_opts->quiet)
+			struct reference ref = {
+				.name = *refs,
+				.oid = &oid,
+			};
+
+			show_one(show_one_opts, &ref);
+		} else if (!show_one_opts->quiet) {
 			die("'%s' - not a valid ref", *refs);
-		else
+		} else {
 			return 1;
+		}
+
 		refs++;
 	}