rev-parse: allow printing compatibility hash

Right now, we have a way to print the storage hash, the input hash, and the output hash, but we lack a way to print the compatibility hash. Add a new type to --show-object-format, compat, which prints this value. If no compatibility hash exists, simply print a newline. This is important to allow users to use multiple options at once while still getting unambiguous output. Signed-off-by: brian m. carlson <sandals@crustytoothpaste.net> Signed-off-by: Junio C Hamano <gitster@pobox.com>

brian m. carlson committed Oct 9, 2025 at 21:56 UTC b95c59e21e6afeddc56400e162e818a9312f04d2
3 files changed +50 -6
Documentation/git-rev-parse.adoc
+6 -5
@@ -324,11 +324,12 @@ The following options are unaffected by `--path-format`:
324 path of the current directory relative to the top-level
325 directory.
326
327 ---show-object-format[=(storage|input|output)]::
328 - Show the object format (hash algorithm) used for the repository
329 - for storage inside the `.git` directory, input, or output. For
330 - input, multiple algorithms may be printed, space-separated.
331 - If not specified, the default is "storage".
327 +--show-object-format[=(storage|input|output|compat)]::
328 + Show the object format (hash algorithm) used for the repository for storage
329 + inside the `.git` directory, input, output, or compatibility. For input,
330 + multiple algorithms may be printed, space-separated. If `compat` is
331 + requested and no compatibility algorithm is enabled, prints an empty line. If
332 + not specified, the default is "storage".
333
334 --show-ref-format::
335 Show the reference storage format used for the repository.
builtin/rev-parse.c
+10 -1
@@ -1108,11 +1108,20 @@ int cmd_rev_parse(int argc,
1108 const char *val = arg ? arg : "storage";
1109
1110 if (strcmp(val, "storage") &&
1111 + strcmp(val, "compat") &&
1112 strcmp(val, "input") &&
1113 strcmp(val, "output"))
1114 die(_("unknown mode for --show-object-format: %s"),
1115 arg);
1115 - puts(the_hash_algo->name);
1116 +
1117 + if (!strcmp(val, "compat")) {
1118 + if (the_repository->compat_hash_algo)
1119 + puts(the_repository->compat_hash_algo->name);
1120 + else
1121 + putchar('\n');
1122 + } else {
1123 + puts(the_hash_algo->name);
1124 + }
1125 continue;
1126 }
1127 if (!strcmp(arg, "--show-ref-format")) {
t/t1500-rev-parse.sh
+34
@@ -207,6 +207,40 @@ test_expect_success 'rev-parse --show-object-format in repo' '
207 grep "unknown mode for --show-object-format: squeamish-ossifrage" err
208 '
209
210 +
211 +test_expect_success 'rev-parse --show-object-format in repo with compat mode' '
212 + mkdir repo &&
213 + (
214 + sane_unset GIT_DEFAULT_HASH &&
215 + cd repo &&
216 + git init --object-format=sha256 &&
217 + git config extensions.compatobjectformat sha1 &&
218 + echo sha256 >expect &&
219 + git rev-parse --show-object-format >actual &&
220 + test_cmp expect actual &&
221 + git rev-parse --show-object-format=storage >actual &&
222 + test_cmp expect actual &&
223 + git rev-parse --show-object-format=input >actual &&
224 + test_cmp expect actual &&
225 + git rev-parse --show-object-format=output >actual &&
226 + test_cmp expect actual &&
227 + echo sha1 >expect &&
228 + git rev-parse --show-object-format=compat >actual &&
229 + test_cmp expect actual &&
230 + test_must_fail git rev-parse --show-object-format=squeamish-ossifrage 2>err &&
231 + grep "unknown mode for --show-object-format: squeamish-ossifrage" err
232 + ) &&
233 + mkdir repo2 &&
234 + (
235 + sane_unset GIT_DEFAULT_HASH &&
236 + cd repo2 &&
237 + git init --object-format=sha256 &&
238 + echo >expect &&
239 + git rev-parse --show-object-format=compat >actual &&
240 + test_cmp expect actual
241 + )
242 +'
243 +
244 test_expect_success 'rev-parse --show-ref-format' '
245 test_detect_ref_format >expect &&
246 git rev-parse --show-ref-format >actual &&