[PATCH] parse-options: don't complete option aliases by default

From: Philippe Blain <redacted>

Since 'OPT_ALIAS' was created in 5c387428f1 (parse-options: don't emit
"ambiguous option" for aliases, 2019-04-29), 'git clone
--git-completion-helper', which is used by the Bash completion script to
list options accepted by clone (via '__gitcomp_builtin'), lists both
'--recurse-submodules' and its alias '--recursive', which was not the
case before since '--recursive' had the PARSE_OPT_HIDDEN flag set, and
options with this flag are skipped by 'parse-options.c::show_gitcomp',
which implements 'git <cmd> --git-completion-helper'.

At the point where 'show_gitcomp' is called in 'parse_options_step',
'preprocess_options' was already called in 'parse_options', so any
aliases are now copies of the original options with a modified help text
indicating they are aliases.

Helpfully, since 64cc539fd2 (parse-options: don't leak alias help
messages, 2021-03-21) these copies have the PARSE_OPT_FROM_ALIAS flag
set, so check that flag early in 'show_gitcomp' and do not print them,
unless the user explicitely requested that *all* completion be shown (by
setting 'GIT_COMPLETION_SHOW_ALL'). After all, if we want to encourage
the use of '--recurse-submodules' over '--recursive', we'd better just
suggest the former.

The only other options alias is 'log' and friends' '--mailmap', which is
an alias for '--use-mailmap', but the Bash completion helpers for these
commands do not use '__gitcomp_builtin', and thus are unnaffected by
this change.

Test the new behaviour in t9902-completion.sh. As a side effect, this
also tests the correct behaviour of GIT_COMPLETION_SHOW_ALL, which was
not tested before. Note that since '__gitcomp_builtin' caches the
options it shows, we need to re-source the completion script to clear
that cache for the second test.

Signed-off-by: Philippe Blain <redacted>
---
    parse-options: don't complete option aliases by default

Published-As: https://github.com/gitgitgadget/git/releases/tag/pr-996%2Fphil-blain%2Fclone-recurse-completion-v1
Fetch-It-Via: git fetch https://github.com/gitgitgadget/git pr-996/phil-blain/clone-recurse-completion-v1
Pull-Request: https://github.com/gitgitgadget/git/pull/996

 parse-options.c       |  2 +-
 t/t9902-completion.sh | 13 +++++++++++++
 2 files changed, 14 insertions(+), 1 deletion(-)

diff --git a/parse-options.c b/parse-options.c
index e6f56768ca5..2abff136a17 100644
--- a/parse-options.c
+++ b/parse-options.c

@@ -585,7 +585,7 @@ static int show_gitcomp(const struct option *opts, int show_all)
 		if (!opts->long_name)
 			continue;
 		if (!show_all &&
-			(opts->flags & (PARSE_OPT_HIDDEN | PARSE_OPT_NOCOMPLETE)))
+			(opts->flags & (PARSE_OPT_HIDDEN | PARSE_OPT_NOCOMPLETE | PARSE_OPT_FROM_ALIAS)))
 			continue;
 
 		switch (opts->type) {

diff --git a/t/t9902-completion.sh b/t/t9902-completion.sh
index cb057ef1613..11573936d58 100755
--- a/t/t9902-completion.sh
+++ b/t/t9902-completion.sh

@@ -2404,6 +2404,19 @@ test_expect_success 'sourcing the completion script clears cached --options' '
 	verbose test -z "$__gitcomp_builtin_notes_edit"
 '
 
+test_expect_success 'option aliases are not shown by default' '
+	test_completion "git clone --recurs" "--recurse-submodules "
+'
+
+test_expect_success 'option aliases are shown with GIT_COMPLETION_SHOW_ALL' '
+	. "$GIT_BUILD_DIR/contrib/completion/git-completion.bash" &&
+	GIT_COMPLETION_SHOW_ALL=1 && export GIT_COMPLETION_SHOW_ALL &&
+	test_completion "git clone --recurs" <<-\EOF
+	--recurse-submodules Z
+	--recursive Z
+	EOF
+'
+
 test_expect_success '__git_complete' '
 	unset -f __git_wrap__git_main &&
 

base-commit: d486ca60a51c9cb1fe068803c3f540724e95e83a
-- 
gitgitgadget

On Thu, Jul 15 2021, Philippe Blain via GitGitGadget wrote:

I'm a bit biased here since I like --recursive better, but let's not
drag that whole argument up again. I don't find the argument in
bb62e0a99fc (clone: teach --recurse-submodules to optionally take a
pathspec, 2017-03-17) convincing enough to have moved such a prominent
use-case to a longer option name.

But, water under the bridge. Aside from that:

For me a Google search for "git clone --recursive" is ~40k results, but
"git clone --recurse-submodules". The former links to various
discussions/docs/stackoverflow answers, often --recurse-submodules isn't
mentioned at all or as an aside.

I think it's unfortunate that we:

 1. Conflate whether something shows up in completion v.s. the
    help. Given its prominence and that "git clone -h" is ~50 lines why
    not note --recursive there.

 2. Don't have the completion aware of these aliases, i.e. "git clone
    --rec<TAB>" before your chance offers a completion of both, that sucks,
    we should fully complete the non-alias instead.

 3. Making it PARSE_OPT_HIDDEN "solves" #2 at the cost of hiding it in
    "git help -h", and now this won't work, but did before:

        git clone --recursi<TAB>

    I.e. even if we didn't want to do #2 *and* wanted to hide it in the
    usage output surely completing an unmbigous prefix is better, even
    if it's a hidden option?

Per-se none of this is a blocker or "we must fix this first" for this
particular change, we have this in many existing cases.

I daresay there's no other alias that's in as wide a use in the wild, so
we should think about this one particularly carefully though.

It's not fully clear from your commit message which of 1-3 you're aiming
for, I think it's more of the "discourage its use". 

Sure, fair enough, but PARSE_OPT_HIDDEN is not a 1=1 mapping to that,
and can often lead to more user confusion.

E.g. the user has used --recursive for years, but can't even find it in
-h (I also think it's a mistake to have entirely removed it from the
docs, even if one agrees with its "deprecation" I'd say we should keep
some "used to be called --recursive" note there).

Philippe Blain via GitGitGadget wrote:

From: Philippe Blain <redacted>

Since 'OPT_ALIAS' was created in 5c387428f1 (parse-options: don't emit
"ambiguous option" for aliases, 2019-04-29), 'git clone
--git-completion-helper', which is used by the Bash completion script to
list options accepted by clone (via '__gitcomp_builtin'), lists both
'--recurse-submodules' and its alias '--recursive', which was not the
case before since '--recursive' had the PARSE_OPT_HIDDEN flag set, and
options with this flag are skipped by 'parse-options.c::show_gitcomp',
which implements 'git <cmd> --git-completion-helper'.

At the point where 'show_gitcomp' is called in 'parse_options_step',
'preprocess_options' was already called in 'parse_options', so any
aliases are now copies of the original options with a modified help text
indicating they are aliases.

Helpfully, since 64cc539fd2 (parse-options: don't leak alias help
messages, 2021-03-21) these copies have the PARSE_OPT_FROM_ALIAS flag
set, so check that flag early in 'show_gitcomp' and do not print them,

Makes sense but I don't think what the patch is doing should be buried
here. I think a separate paragraph explaining what you are trying to do
will be better.

unless the user explicitely requested that *all* completion be shown (by
setting 'GIT_COMPLETION_SHOW_ALL'). After all, if we want to encourage
the use of '--recurse-submodules' over '--recursive', we'd better just
suggest the former.

The only other options alias is 'log' and friends' '--mailmap', which is
an alias for '--use-mailmap', but the Bash completion helpers for these
commands do not use '__gitcomp_builtin', and thus are unnaffected by
this change.

Test the new behaviour in t9902-completion.sh. As a side effect, this
also tests the correct behaviour of GIT_COMPLETION_SHOW_ALL, which was
not tested before. Note that since '__gitcomp_builtin' caches the
options it shows, we need to re-source the completion script to clear
that cache for the second test.

I agree this is better, and the patch itself looks obviously correct.

Reviewed-by: Felipe Contreras <redacted>

-- 
Felipe Contreras

Ævar Arnfjörð Bjarmason wrote:

On Thu, Jul 15 2021, Philippe Blain via GitGitGadget wrote:

I'm a bit biased here since I like --recursive better, but let's not
drag that whole argument up again. I don't find the argument in
bb62e0a99fc (clone: teach --recurse-submodules to optionally take a
pathspec, 2017-03-17) convincing enough to have moved such a prominent
use-case to a longer option name.

I agree.

But, water under the bridge. Aside from that:

For me a Google search for "git clone --recursive" is ~40k results, but
"git clone --recurse-submodules". The former links to various
discussions/docs/stackoverflow answers, often --recurse-submodules isn't
mentioned at all or as an aside.

It would be nice if facts could be used as evidence of a UI mistake, but
alas in my experience that has never been the case.

I think it's unfortunate that we:

 1. Conflate whether something shows up in completion v.s. the
    help. Given its prominence and that "git clone -h" is ~50 lines why
    not note --recursive there.

Agreed.

 2. Don't have the completion aware of these aliases, i.e. "git clone
    --rec<TAB>" before your chance offers a completion of both, that sucks,
    we should fully complete the non-alias instead.

Yes, that's what would happen with the patch.

 3. Making it PARSE_OPT_HIDDEN "solves" #2 at the cost of hiding it in
    "git help -h", and now this won't work, but did before:

        git clone --recursi<TAB>

    I.e. even if we didn't want to do #2 *and* wanted to hide it in the
    usage output surely completing an unmbigous prefix is better, even
    if it's a hidden option?

This is something that could be done in zsh, but not in bash (at least
not easily).

E.g. the user has used --recursive for years, but can't even find it in
-h (I also think it's a mistake to have entirely removed it from the
docs, even if one agrees with its "deprecation" I'd say we should keep
some "used to be called --recursive" note there).

But that is not a problem of this patch. If users can't find --recursive
and complain about it, then that's actually a good thing, because now
the facts about --recursive vs. --recurse-submodules are not needed
anymore, and we could just fix the interface.

-- 
Felipe Contreras

Hi Felipe,

Le 2021-07-15 à 13:04, Felipe Contreras a écrit :

Philippe Blain via GitGitGadget wrote:

quoted

From: Philippe Blain <redacted>


Helpfully, since 64cc539fd2 (parse-options: don't leak alias help
messages, 2021-03-21) these copies have the PARSE_OPT_FROM_ALIAS flag
set, so check that flag early in 'show_gitcomp' and do not print them,

Makes sense but I don't think what the patch is doing should be buried
here. I think a separate paragraph explaining what you are trying to do
will be better.

Indeed. Will clarify.

I agree this is better, and the patch itself looks obviously correct.

Reviewed-by: Felipe Contreras <redacted>

Thanks!

Philippe.

Hi Ævar,

Le 2021-07-15 à 12:16, Ævar Arnfjörð Bjarmason a écrit :

I'm a bit biased here since I like --recursive better, but let's not
drag that whole argument up again. I don't find the argument in
bb62e0a99fc (clone: teach --recurse-submodules to optionally take a
pathspec, 2017-03-17) convincing enough to have moved such a prominent
use-case to a longer option name.

But, water under the bridge. Aside from that:

For me a Google search for "git clone --recursive" is ~40k results, but
"git clone --recurse-submodules". The former links to various
discussions/docs/stackoverflow answers, often --recurse-submodules isn't
mentioned at all or as an aside.

I think it's unfortunate that we:

  1. Conflate whether something shows up in completion v.s. the
     help. Given its prominence and that "git clone -h" is ~50 lines why
     not note --recursive there.

As far as I understand (and tested), '--recursive' was listed in the short help but not the completion
before bb62e0a99f (clone: teach --recurse-submodules to optionally take a pathspec,
2017-03-17). At the time the completion did not use '--git-completion-helper'
and only '--recurse-submodules' was listed (since 5f072e0017 (completion: add option
'--recurse-submodules' to 'git clone', 2016-07-27)).

Starting from bb62e0a99f, it was not listed in the short help (because of PARSE_OPT_HIDDEN)
nor the completion (because it was still not listed).

Then starting from 5c387428f1 (parse-options: don't emit "ambiguous option"
for aliases, 2019-04-29), it started being listed in the short help AND
the completion again; in the short help because of the new code in usage_with_options_internal
and in the completion because of the way preprocess_options is implemented,
and at that time '--git-completion-helper' was used for '_git_clone'.

After my patch, it would still be listed in the short help, as "alias of --recurse-submodules",
but would not be listed by the completion (unless GIT_COMPLETION_SHOW_ALL is set).

  2. Don't have the completion aware of these aliases, i.e. "git clone
     --rec<TAB>" before your chance offers a completion of both, that sucks,
     we should fully complete the non-alias instead.

Indeed. That's my main motivation.

  3. Making it PARSE_OPT_HIDDEN "solves" #2 at the cost of hiding it in
     "git help -h", and now this won't work, but did before:

         git clone --recursi<TAB>

     I.e. even if we didn't want to do #2 *and* wanted to hide it in the
     usage output surely completing an unmbigous prefix is better, even
     if it's a hidden option?

I agree that with my patch 'git clone --recursi<TAB>' does not complete to '--recursive'
(unless you've set GIT_COMPLETION_SHOW_ALL). But I'm not sure it's that big of
a deal (after all if you typed this far you only have two letters left :P)
But '--rec' will be sufficient to complete to '--recurse-submoduele', so
it's even less letters to type.

But this has nothing to do with PARSE_OPT_HIDDEN ('--recurse-submodules' is
not hidden and aliases are not hidden either). So I'm not sure what you mean...

Per-se none of this is a blocker or "we must fix this first" for this
particular change, we have this in many existing cases.

I daresay there's no other alias that's in as wide a use in the wild, so
we should think about this one particularly carefully though.

It's not fully clear from your commit message which of 1-3 you're aiming
for, I think it's more of the "discourage its use".

As I wrote it's mainly #2, I'll update the commit message to be clearer.

Sure, fair enough, but PARSE_OPT_HIDDEN is not a 1=1 mapping to that,
and can often lead to more user confusion.

E.g. the user has used --recursive for years, but can't even find it in
-h (I also think it's a mistake to have entirely removed it from the
docs, even if one agrees with its "deprecation" I'd say we should keep
some "used to be called --recursive" note there).

Yeah, maybe it should have stayed in the docs. Again, my patch does not remove
it from the short help.

Thanks for you comments!:)

Philippe.

From: Philippe Blain <redacted>

Since 'OPT_ALIAS' was created in 5c387428f1 (parse-options: don't emit
"ambiguous option" for aliases, 2019-04-29), 'git clone
--git-completion-helper', which is used by the Bash completion script to
list options accepted by clone (via '__gitcomp_builtin'), lists both
'--recurse-submodules' and its alias '--recursive', which was not the
case before since '--recursive' had the PARSE_OPT_HIDDEN flag set, and
options with this flag are skipped by 'parse-options.c::show_gitcomp',
which implements 'git <cmd> --git-completion-helper'.

This means that typing 'git clone --recurs<TAB>' will yield both
'--recurse-submodules' and '--recursive', which is not ideal since both
do the same thing, and so the completion should directly complete the
canonical option.

At the point where 'show_gitcomp' is called in 'parse_options_step',
'preprocess_options' was already called in 'parse_options', so any
aliases are now copies of the original options with a modified help text
indicating they are aliases.

Helpfully, since 64cc539fd2 (parse-options: don't leak alias help
messages, 2021-03-21) these copies have the PARSE_OPT_FROM_ALIAS flag
set, so check that flag early in 'show_gitcomp' and do not print them,
unless the user explicitely requested that *all* completion be shown (by
setting 'GIT_COMPLETION_SHOW_ALL'). After all, if we want to encourage
the use of '--recurse-submodules' over '--recursive', we'd better just
suggest the former.

The only other options alias is 'log' and friends' '--mailmap', which is
an alias for '--use-mailmap', but the Bash completion helpers for these
commands do not use '__gitcomp_builtin', and thus are unnaffected by
this change.

Test the new behaviour in t9902-completion.sh. As a side effect, this
also tests the correct behaviour of GIT_COMPLETION_SHOW_ALL, which was
not tested before. Note that since '__gitcomp_builtin' caches the
options it shows, we need to re-source the completion script to clear
that cache for the second test.

Signed-off-by: Philippe Blain <redacted>
---
    parse-options: don't complete option aliases by default
    
    Changes since v1:
    
     * Added a paragraph to the commit message to clarify that the goal of
       this patch is to have the completion show only the canonical option
       and not its alias.

Published-As: https://github.com/gitgitgadget/git/releases/tag/pr-996%2Fphil-blain%2Fclone-recurse-completion-v2
Fetch-It-Via: git fetch https://github.com/gitgitgadget/git pr-996/phil-blain/clone-recurse-completion-v2
Pull-Request: https://github.com/gitgitgadget/git/pull/996

Range-diff vs v1:

 1:  091a59323b7 ! 1:  9ae43e17e0c parse-options: don't complete option aliases by default
     @@ Commit message
          options with this flag are skipped by 'parse-options.c::show_gitcomp',
          which implements 'git <cmd> --git-completion-helper'.
      
     +    This means that typing 'git clone --recurs<TAB>' will yield both
     +    '--recurse-submodules' and '--recursive', which is not ideal since both
     +    do the same thing, and so the completion should directly complete the
     +    canonical option.
     +
          At the point where 'show_gitcomp' is called in 'parse_options_step',
          'preprocess_options' was already called in 'parse_options', so any
          aliases are now copies of the original options with a modified help text


 parse-options.c       |  2 +-
 t/t9902-completion.sh | 13 +++++++++++++
 2 files changed, 14 insertions(+), 1 deletion(-)

diff --git a/parse-options.c b/parse-options.c
index e6f56768ca5..2abff136a17 100644
--- a/parse-options.c
+++ b/parse-options.c

@@ -585,7 +585,7 @@ static int show_gitcomp(const struct option *opts, int show_all)
 		if (!opts->long_name)
 			continue;
 		if (!show_all &&
-			(opts->flags & (PARSE_OPT_HIDDEN | PARSE_OPT_NOCOMPLETE)))
+			(opts->flags & (PARSE_OPT_HIDDEN | PARSE_OPT_NOCOMPLETE | PARSE_OPT_FROM_ALIAS)))
 			continue;
 
 		switch (opts->type) {

diff --git a/t/t9902-completion.sh b/t/t9902-completion.sh
index cb057ef1613..11573936d58 100755
--- a/t/t9902-completion.sh
+++ b/t/t9902-completion.sh

@@ -2404,6 +2404,19 @@ test_expect_success 'sourcing the completion script clears cached --options' '
 	verbose test -z "$__gitcomp_builtin_notes_edit"
 '
 
+test_expect_success 'option aliases are not shown by default' '
+	test_completion "git clone --recurs" "--recurse-submodules "
+'
+
+test_expect_success 'option aliases are shown with GIT_COMPLETION_SHOW_ALL' '
+	. "$GIT_BUILD_DIR/contrib/completion/git-completion.bash" &&
+	GIT_COMPLETION_SHOW_ALL=1 && export GIT_COMPLETION_SHOW_ALL &&
+	test_completion "git clone --recurs" <<-\EOF
+	--recurse-submodules Z
+	--recursive Z
+	EOF
+'
+
 test_expect_success '__git_complete' '
 	unset -f __git_wrap__git_main &&
 

base-commit: d486ca60a51c9cb1fe068803c3f540724e95e83a
-- 
gitgitgadget