[PATCH v2] stash: print the correct usage on "git stash [push] --invalid-option"

Change the usage message emitted by "git stash --invalid-option" to emit usage information for "git stash" in general, and not just for the "push" command. I.e. before:

    $ git stash --blah
    error: unknown option `blah'
    usage: git stash [push [-p|--patch] [-k|--[no-]keep-index] [-q|--quiet]
              [-u|--include-untracked] [-a|--all] [-m|--message <message>]
              [--] [<pathspec>...]]
    [...]

After:

    $ git stash --blah
    error: unknown option `blah'
    usage: git stash list [<options>]
       or: git stash show [<options>] [<stash>]
       or: git stash drop [-q|--quiet] [<stash>]
       or: git stash ( pop | apply ) [--index] [-q|--quiet] [<stash>]
       or: git stash branch <branchname> [<stash>]
       or: git stash clear
       or: git stash [push [-p|--patch] [-k|--[no-]keep-index] [-q|--quiet]
              [-u|--include-untracked] [-a|--all] [-m|--message <message>]
              [--pathspec-from-file=<file> [--pathspec-file-nul]]
              [--] [<pathspec>...]]
       or: git stash save [-p|--patch] [-k|--[no-]keep-index] [-q|--quiet]
              [-u|--include-untracked] [-a|--all] [<message>]
    [...]

We'll only emit the former on the likes of "git stash push --blah" now.

That we emitted the usage for just "push" in the case of the subcommand not being explicitly specified was an unintentional side-effect of how it was implemented. When it was converted to C in d553f538b8a (stash: convert push to builtin, 2019-02-25) the pattern of having per-subcommand usage information was rightly continued. The Git-stash.sh shellscript did not have that, and always printed the equivalent of "git_stash_usage".

But in doing so the case of push being implicit and explicit was conflated. A variable was added to track this in 8c3713cede7 (stash: eliminate crude option parsing, 2020-02-17), but it did not update the usage output accordingly.

This still leaves e.g. "git stash push -h" emitting the "git_stash_usage" output, instead of "git_stash_push_usage". That should be fixed, but is a much deeper misbehavior in parse_options() not being aware of subcommands at all. I.e. in how PARSE_OPT_KEEP_UNKNOWN and PARSE_OPT_NO_INTERNAL_HELP combine in commands such as "git stash".

Perhaps PARSE_OPT_KEEP_UNKNOWN should imply PARSE_OPT_NO_INTERNAL_HELP, or better yet parse_options() should be extended to fully handle these subcommand cases that we handle manually in "git stash", "git commit-graph", "git multi-pack-index" etc. All of those musings would be a much bigger change than this isolated fix though, so let's leave that for some other time.

Signed-off-by: Ævar Arnfjörð Bjarmason <avarab@gmail.com>
---

A trivial patch for a small issue in "git stash" usage, unrelated and non-conflicting with my other series to improve usage output alignment at https://lore.kernel.org/git/cover-v5-0.4-00000000000-20210921T132350Z-avarab@gmail.com/

Range-diff against v1:
1:  47c582f1218 ! 1:  d1b9790904c stash: print the correct usage on "git stash [push] --invalid-option"
    @@ Commit message
     
         Change the usage message emitted by "git stash --invalid-option" to
         emit usage information for "git stash" in general, and not just for
    -    the "push" command.
    +    the "push" command. I.e. before:
    +
    +        $ git stash --blah
    +        error: unknown option `blah'
    +        usage: git stash [push [-p|--patch] [-k|--[no-]keep-index] [-q|--quiet]
    +                  [-u|--include-untracked] [-a|--all] [-m|--message <message>]
    +                  [--] [<pathspec>...]]
    +        [...]
    +
    +    After:
    +
    +        $ git stash --blah
    +        error: unknown option `blah'
    +        usage: git stash list [<options>]
    +           or: git stash show [<options>] [<stash>]
    +           or: git stash drop [-q|--quiet] [<stash>]
    +           or: git stash ( pop | apply ) [--index] [-q|--quiet] [<stash>]
    +           or: git stash branch <branchname> [<stash>]
    +           or: git stash clear
    +           or: git stash [push [-p|--patch] [-k|--[no-]keep-index] [-q|--quiet]
    +                  [-u|--include-untracked] [-a|--all] [-m|--message <message>]
    +                  [--pathspec-from-file=<file> [--pathspec-file-nul]]
    +                  [--] [<pathspec>...]]
    +           or: git stash save [-p|--patch] [-k|--[no-]keep-index] [-q|--quiet]
    +                  [-u|--include-untracked] [-a|--all] [<message>]
    +        [...]
    +
    +    We'll only emit the former on the likes of "git stash push --blah"
    +    now.
     
         That we emitted the usage for just "push" in the case of the
         subcommand not being explicitly specified was an unintentional
    @@ Commit message
         But in doing so the case of push being implicit and explicit was
         conflated. A variable was added to track this in 8c3713cede7 (stash:
         eliminate crude option parsing, 2020-02-17), but it did not update the
    -    usage output accordingly. Let's do that.
    +    usage output accordingly.
     
         This still leaves e.g. "git stash push -h" emitting the
         "git_stash_usage" output, instead of "git_stash_push_usage". That
    @@ t/t3903-stash.sh: export GIT_TEST_DEFAULT_INITIAL_BRANCH_NAME
      
      . ./test-lib.sh
      
    -+test_expect_success 'usage' '
    -+	test_expect_code 129 git stash -h >out &&
    -+	grep "or: git stash" out &&
    ++test_expect_success 'usage on cmd and subcommand invalid option' '
    ++	test_expect_code 129 git stash --invalid-option 2>usage &&
    ++	grep "or: git stash" usage &&
     +
    -+	test_expect_code 129 git stash --invalid-option >out 2>err &&
    -+	grep "or: git stash" err &&
    ++	test_expect_code 129 git stash push --invalid-option 2>usage &&
    ++	! grep "or: git stash" usage
    ++'
    ++
    ++test_expect_success 'usage on main command -h emits a summary of subcommands' '
    ++	test_expect_code 129 git stash -h >usage &&
    ++	grep -F "usage: git stash list" usage &&
    ++	grep -F "or: git stash show" usage
    ++'
     +
    -+	test_expect_code 129 git stash push --invalid-option >out 2>err &&
    -+	! grep "or: git stash" err
    ++test_expect_failure 'usage for subcommands should emit subcommand usage' '
    ++	test_expect_code 129 git stash push -h >usage &&
    ++	grep -F "usage: git stash [push" usage
     +'
     +
      diff_cmp () {

 builtin/stash.c  |  1 +
 t/t3903-stash.sh | 19 +++++++++++++++++++
 2 files changed, 20 insertions(+)