completion: improve doc for complex aliases

From: Philippe Blain <[email protected]>

The completion code can be told to use a particular completion for aliases that shell out by using ': git <cmd> ;' as the first command of the alias. This only works if <cmd> and the semicolon are separated by a space. The examples have that space but it's not clear if it's just for style or if it's mandatory.

Explicitely mention it.

---
completion: improve doc for complex aliases

The completion code can be told to use a particular completion for aliases that shell out by using ': git ;' as the first command of the alias. This only works if and the semicolon are separated by a space. The examples have that space but it's not clear if it's just for style or if it's mandatory.

Explicitely mention it.

Published-As: https://github.com/gitgitgadget/git/releases/tag/pr-1585%2Fphil-blain%2Fcompletion-shell-aliases-doc-v1
Fetch-It-Via: git fetch https://github.com/gitgitgadget/git pr-1585/phil-blain/completion-shell-aliases-doc-v1
Pull-Request: https://github.com/gitgitgadget/git/pull/1585

 contrib/completion/git-completion.bash | 1 +
 1 file changed, 1 insertion(+)

index dc95c34cc85..659df570496 100644
@@ -28,6 +28,7 @@
 # completion style.  For example '!f() { : git commit ; ... }; f' will
 # tell the completion to use commit completion.  This also works with aliases
 # of form "!sh -c '...'".  For example, "!sh -c ': git commit ; ... '".
+# Be sure to add a space between the command name and the ';'.
 #
 # If you have a command that is not part of git, but you would still
 # like completion, you can use __git_complete:

base-commit: 23c56f7bd5f1667f8b793d796bf30e39545920f6

gitgitgadget

s/Explicitely/Explicitly/

Hi Philippe,

It would be even more helpful if you explain _why_ it is mandatory in the commit message. Is there some Bash-specific behavior or something else going on here?

If you are unable to explain why, then as an alternative you could explain the error or buggy behavior (any error messages encountered, for example) you observe on your system when you do not use the space (which is corrected by applying the suggestion you are adding in this patch).

Thanks!

Hi Linus,

Le 2023-09-11 à 21:04, Linus Arver a écrit :

Yeah, I guess I did not investigate why it did not work without the space, it would be more complete if I did.

There's no error message though, it just does not work without the space (as I wrote in the commit message) in the sense that it won't suggest completion for the git command '<cmd>'.

I'll investigate and update the commit message.

Thanks,
Philippe.

From: Philippe Blain <[email protected]>

The completion code can be told to use a particular completion for aliases that shell out by using ': git <cmd> ;' as the first command of the alias. This only works if <cmd> and the semicolon are separated by a space, since if the space is missing __git_aliased_command returns (for example) 'checkout;' instead of just 'checkout', and then __git_complete_command fails to find a completion for 'checkout;'.

The examples have that space but it's not clear if it's just for style or if it's mandatory. Explicitly mention it.

---
completion: improve doc for complex aliases

Changes since v1:

* fixed the typo pointed out by Eric
* added an explanation of why the space is mandatory, as suggested by Linus

Published-As: https://github.com/gitgitgadget/git/releases/tag/pr-1585%2Fphil-blain%2Fcompletion-shell-aliases-doc-v2
Fetch-It-Via: git fetch https://github.com/gitgitgadget/git pr-1585/phil-blain/completion-shell-aliases-doc-v2
Pull-Request: https://github.com/gitgitgadget/git/pull/1585

Range-diff vs v1:

1: b3621ed25f0 ! 1: 96a0867c5ad completion: improve doc for complex aliases
@@ Commit message
The completion code can be told to use a particular completion for aliases that shell out by using ': git <cmd> ;' as the first command of the alias. This only works if <cmd> and the semicolon are separated by a
- space. The examples have that space but it's not clear if it's just for
- style or if it's mandatory.
+ space, since if the space is missing __git_aliased_command returns (for
+ example) 'checkout;' instead of just 'checkout', and then
+ __git_complete_command fails to find a completion for 'checkout;'.

- Explicitely mention it.
+ The examples have that space but it's not clear if it's just for
+ style or if it's mandatory. Explicitly mention it.

 contrib/completion/git-completion.bash | 1 +
 1 file changed, 1 insertion(+)

index dc95c34cc85..659df570496 100644
@@ -28,6 +28,7 @@
 # completion style.  For example '!f() { : git commit ; ... }; f' will
 # tell the completion to use commit completion.  This also works with aliases
 # of form "!sh -c '...'".  For example, "!sh -c ': git commit ; ... '".
+# Be sure to add a space between the command name and the ';'.
 #
 # If you have a command that is not part of git, but you would still
 # like completion, you can use __git_complete:

base-commit: 23c56f7bd5f1667f8b793d796bf30e39545920f6

gitgitgadget

Thanks. I scanned the case statement in the loop in the function and thought "hmph, everybody says ': git <cmd> ;' but is 'git' really needed?"

I had "git l3" alias that invokes "$HOM#/bin/git-l" command, like so:

    [alias]
            l3 = "!sh -c ': git log ; git l \"$@\"' -"

but if I did 's/: git log/: log/' it still completes just fine.

I wonder if this hack is worth adding, instead of (or in addition to) requiring the user to insert $IFS to please the "parser", we can honor the rather obvious wish of the user in a more direct way.

 contrib/completion/git-completion.bash | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

index 19139ac121..e31d71955f 100644
@@ -1183,7 +1183,7 @@ __git_aliased_command ()
 			:)	: skip null command ;;
 			\'*)	: skip opening quote after sh -c ;;
 			*)
-				cur="$word"
+				cur="${word%;}"
 				break
 			esac
 		done

Interesting! I searched for the 'git <cmd>' and got some hits in "t9902-completion.sh" when running "git grep -nE 'git <cmd>'":

    t/t9902-completion.sh:2432:test_expect_success "completion uses <cmd> completion for alias: !sh -c 'git <cmd> ...'" '
    t/t9902-completion.sh:2441:test_expect_success 'completion uses <cmd> completion for alias: !f () { VAR=val git <cmd> ... }' '
    t/t9902-completion.sh:2450:test_expect_success 'completion used <cmd> completion for alias: !f() { : git <cmd> ; ... }' '

When I did 's/: git log/: log/' in the test at line 2450, the test still passed. Perhaps we should add this "git"-less version as another test case?

Thanks for the investigation. The commit message reads much better now.

This LGTM, but I think Junio's review comments [1] are worth considering. I'll respond there also.

[1] https://lore.kernel.org/git/[email protected]/#t

Recently we started to tell users to spell ": git foo ;" with space(s) around 'foo' for an alias to be completed similarly to the 'git foo' command. It however is easy to also allow users to spell it in a more natural way with the semicolon attached to 'foo', i.e. ": git foo;". Also, add a comment to note that 'git' is optional and writing ": foo;" would complete the alias just fine.

---

* We've discussed this when we reviewed the topic that just hit 'master'. Before we forget...

 contrib/completion/git-completion.bash | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

index 47fd664ea5..477ef8157a 100644
@@ -28,7 +28,8 @@
 # completion style.  For example '!f() { : git commit ; ... }; f' will
 # tell the completion to use commit completion.  This also works with aliases
 # of form "!sh -c '...'".  For example, "!sh -c ': git commit ; ... '".
-# Be sure to add a space between the command name and the ';'.
+# Note that "git" is optional --- '!f() { : commit; ...}; f' would complete
+# just like the 'git commit' command.
 #
 # If you have a command that is not part of git, but you would still
 # like completion, you can use __git_complete:

@@ -1183,7 +1184,7 @@ __git_aliased_command ()
 			:)	: skip null command ;;
 			\'*)	: skip opening quote after sh -c ;;
 			*)
-				cur="$word"
+				cur="${word%;}"
 				break
 			esac
 		done

And here is an obligatory "test" update I will squash into the main patch. The new ones copy a canonical ": git <cmd> ; ..." test and remove 'git' and also the space before the semicolon.

index 47e20fb8b1..a7c3b4eb63 100755
@@ -2464,6 +2464,24 @@ test_expect_success 'completion used <cmd> completion for alias: !f() { : git <c
 	EOF
 '
 
+test_expect_success 'completion used <cmd> completion for alias: !f() { : <cmd> ; ... }' '
+	test_config alias.co "!f() { : checkout ; if ... } f" &&
+	test_completion "git co m" <<-\EOF
+	main Z
+	mybranch Z
+	mytag Z
+	EOF
+'
+
+test_expect_success 'completion used <cmd> completion for alias: !f() { : <cmd>; ... }' '
+	test_config alias.co "!f() { : checkout; if ... } f" &&
+	test_completion "git co m" <<-\EOF
+	main Z
+	mybranch Z
+	mytag Z
+	EOF
+'
+
 test_expect_success 'completion without explicit _git_xxx function' '
 	test_completion "git version --" <<-\EOF
 	--build-options Z

Thanks for reading.