Subject: Re: [PATCH] cat-file: fix error and warning message formatting

From: Engr Md Ferdous Alam <[email-masked]>
Date: Mon, 23 Feb 2026 18:54:11 +0000 (UTC)

Junio C Hamano <[email-masked]> writes:

> It may be cleaner to deal with "Not a valid object name %s" that
> appear in 5 other .c files in addition to cat-file.c in a single
> patch (touching no other messages, just the "Not a valid object
> name" one), and do the rest of cat-file.c in a second patch.

Done in v2.  The series is now split into two patches:

  [1/2] die: lowercase "Not a valid object name" messages
        (cat-file.c, describe.c, ls-tree.c, merge-base.c,
         read-tree.c, unpack-file.c and their test expectations)
  [2/2] cat-file: fix remaining error and warning message formatting
        ("Cannot read object" and the promisor remotes warning)

> Have you audited third-party software that use Git plumbing commands
> like "git cat-file" to make sure that they do not expect the current
> and historical spelling to make sure this change will not break them?

I did a broad search across GitHub.  Here is what I found:

Several widely-used projects do case-sensitive string matching on
"fatal: Not a valid object name" in stderr output from Git commands:

  - Gitea (go-gitea/gitea) -- strings.Contains() in Go
  - Gogs (gogs/gogs) -- strings.Contains() in Go
  - GitLab Gitaly -- strings.HasPrefix() in Go
  - JetBrains IntelliJ -- startsWith() in Java
  - Harness CI/CD -- strings.HasPrefix() in Go (3 locations)
  - Review Board -- startswith() in Python
  - Tencent CodeAnalysis -- regex match in Python
  - DataLad -- "in" string check in Python
  - elastic/docs tooling -- .includes() in JavaScript
  - prettier-standard -- exact === equality in JavaScript

On the other hand, these are NOT affected:

  - Pure Git reimplementations (libgit2, JGit, go-git, Dulwich,
    isomorphic-git, GitPython) generate their own messages.
  - GitKraken GitLens already uses case-insensitive matching (/i).
  - VS Code Git extension and GitHub Desktop do not match this
    specific message.
  - Many CI/CD tools (Nx, BuildKit, Skaffold, Flutter) rely on
    exit codes rather than message text.

A handful of projects already check for the lowercase form "not a
valid object name", suggesting the ecosystem is in transition, but
the majority still expect the capitalized form.

Given the risk of silently breaking error detection in projects like
Gitea, Gogs, Gitaly, and IntelliJ, I am not sure whether it is
worth proceeding with patch [1/2].  Patch [2/2] changes messages
that are far less likely to be parsed by external tools ("Cannot
read object" and the promisor remotes warning).

How would you like to proceed?  Should we:

  (a) keep both patches as-is and let downstream projects adapt,
  (b) drop patch [1/2] and only ship [2/2], or
  (c) take a different approach?

Thanks,
Md Ferdous Alam

On Monday, February 23, 2026 at 09:54:52 PM GMT+6, Junio C Hamano <[email-masked]> wrote: 

"Md Ferdous Alam via GitGitGadget" <[email-masked]> writes:

> From: mdferdousalam <[email-masked]>
>
> The CodingGuidelines state that error messages should not begin
> with a capital letter and should not end with a full stop.  Fix
> the die(), error() and warning() messages in builtin/cat-file.c
> that violate these rules, and update the corresponding test
> expectations in t1006 and t8007.
>
> Signed-off-by: mdferdousalam <[email-masked]>
> ---
>    cat-file: fix error and warning message formatting
>
> Published-As: https://github.com/gitgitgadget/git/releases/tag/pr-2052%2Fmdferdousalam%2Ffix-error-messages-cat-file-v1
> Fetch-It-Via: git fetch https://github.com/gitgitgadget/git pr-2052/mdferdousalam/fix-error-messages-cat-file-v1
> Pull-Request: https://github.com/gitgitgadget/git/pull/2052

It may be cleaner to deal with "Not a valid object name %s" that
appear in 5 other .c files in addition to cat-file.c in a single
patch (touching no other messages, just the "Not a valid object
name" one), and do the rest of cat-file.c in a second patch.

Have you audited third-party software that use Git plumbing commands
like "git cat-file" to make sure that they do not expect the current
and historical spelling to make sure this change will not break them?

Other than that, looking good.  Thanks for working on it.

>
>  builtin/cat-file.c          | 8 ++++----
>  t/t1006-cat-file.sh          | 6 +++---
>  t/t8007-cat-file-textconv.sh | 2 +-
>  3 files changed, 8 insertions(+), 8 deletions(-)
>
> diff --git a/builtin/cat-file.c b/builtin/cat-file.c
> index df8e87a81f..a8d564dd6a 100644
> --- a/builtin/cat-file.c
> +++ b/builtin/cat-file.c
> @@ -121,7 +121,7 @@ static int cat_one_file(int opt, const char *exp_type, const char *obj_name)
>  
>      if (get_oid_with_context(the_repository, obj_name, get_oid_flags, &oid,
>                  &obj_context))
> -        die("Not a valid object name %s", obj_name);
> +        die("not a valid object name %s", obj_name);
>  
>      if (!path)
>          path = obj_context.path;
> @@ -182,7 +182,7 @@ static int cat_one_file(int opt, const char *exp_type, const char *obj_name)
>      case 'p':
>          type = odb_read_object_info(the_repository->objects, &oid, NULL);
>          if (type < 0)
> -            die("Not a valid object name %s", obj_name);
> +            die("not a valid object name %s", obj_name);
>  
>          /* custom pretty-print here */
>          if (type == OBJ_TREE) {
> @@ -200,7 +200,7 @@ static int cat_one_file(int opt, const char *exp_type, const char *obj_name)
>          buf = odb_read_object(the_repository->objects, &oid,
>                        &type, &size);
>          if (!buf)
> -            die("Cannot read object %s", obj_name);
> +            die("cannot read object %s", obj_name);
>  
>          if (use_mailmap) {
>              size_t s = size;
> @@ -910,7 +910,7 @@ static int batch_objects(struct batch_options *opt)
>              data.skip_object_info = 1;
>  
>          if (repo_has_promisor_remote(the_repository))
> -            warning("This repository uses promisor remotes. Some objects may not be loaded.");
> +            warning("this repository uses promisor remotes; some objects may not be loaded");
>  
>          disable_replace_refs();
>  
> diff --git a/t/t1006-cat-file.sh b/t/t1006-cat-file.sh
> index 0eee3bb878..0283c7400d 100755
> --- a/t/t1006-cat-file.sh
> +++ b/t/t1006-cat-file.sh
> @@ -705,7 +705,7 @@ do
>          then
>              cat >expect <<-EOF
>              error: header for $bogus_long_oid too long, exceeds 32 bytes
> -            fatal: Not a valid object name $bogus_long_oid
> +            fatal: not a valid object name $bogus_long_oid
>              EOF
>          else
>              cat >expect <<-EOF
> @@ -721,7 +721,7 @@ do
>  
>      test_expect_success "cat-file $arg1 error on missing short OID" '
>          cat >expect.err <<-EOF &&
> -        fatal: Not a valid object name $(test_oid deadbeef_short)
> +        fatal: not a valid object name $(test_oid deadbeef_short)
>          EOF
>          test_must_fail git cat-file $arg1 $(test_oid deadbeef_short) >out 2>err.actual &&
>          test_must_be_empty out &&
> @@ -732,7 +732,7 @@ do
>          if test "$arg1" = "-p"
>          then
>              cat >expect.err <<-EOF
> -            fatal: Not a valid object name $(test_oid deadbeef)
> +            fatal: not a valid object name $(test_oid deadbeef)
>              EOF
>          else
>              cat >expect.err <<-\EOF
> diff --git a/t/t8007-cat-file-textconv.sh b/t/t8007-cat-file-textconv.sh
> index c3735fb50d..3a69b03794 100755
> --- a/t/t8007-cat-file-textconv.sh
> +++ b/t/t8007-cat-file-textconv.sh
> @@ -22,7 +22,7 @@ test_expect_success 'setup ' '
>  
>  test_expect_success 'usage: <bad rev>' '
>      cat >expect <<-\EOF &&
> -    fatal: Not a valid object name HEAD2
> +    fatal: not a valid object name HEAD2
>      EOF
>      test_must_fail git cat-file --textconv HEAD2 2>actual &&
>      test_cmp expect actual
>
> base-commit: 7c02d39fc2ed2702223c7674f73150d9a7e61ba4