doc: use 'ref' instead of 'commit' for merge-base arguments

From: Takuya Noguchi <[email protected]>

The notation <commit> can be misunderstandable only for commit SHA1, but merge-base accepts any commit references. Like reflog, the name of arguments should be <ref> instead of <commit>.

---
doc: use 'ref' instead of 'commit' for merge-base arguments

The notation <commit> can be misunderstandable only for commit SHA1, but merge-base accepts any commit references. Like reflog, the name of arguments should be <ref> rather than <commit>.

Published-As: https://github.com/gitgitgadget/git/releases/tag/pr-git-719%2Ftnir%2Fmerge-base-supporting-refs-v1
Fetch-It-Via: git fetch https://github.com/gitgitgadget/git pr-git-719/tnir/merge-base-supporting-refs-v1
Pull-Request: https://github.com/git/git/pull/719

 Documentation/git-merge-base.txt | 10 +++++-----
 builtin/merge-base.c             | 12 ++++++------
 2 files changed, 11 insertions(+), 11 deletions(-)

index 2d944e0851f..b87528ef269 100644
@@ -9,11 +9,11 @@ git-merge-base - Find as good common ancestors as possible for a merge
 SYNOPSIS
 --------
 [verse]
-'git merge-base' [-a|--all] <commit> <commit>...
-'git merge-base' [-a|--all] --octopus <commit>...
-'git merge-base' --is-ancestor <commit> <commit>
-'git merge-base' --independent <commit>...
-'git merge-base' --fork-point <ref> [<commit>]
+'git merge-base' [-a|--all] <ref> <ref>...
+'git merge-base' [-a|--all] --octopus <ref>...
+'git merge-base' --is-ancestor <ref> <ref>
+'git merge-base' --independent <ref>...
+'git merge-base' --fork-point <ref> [<ref>]
 
 DESCRIPTION
 -----------

index e3f8da13b69..910916ae0ec 100644
@@ -29,11 +29,11 @@ static int show_merge_base(struct commit **rev, int rev_nr, int show_all)
 }
 
 static const char * const merge_base_usage[] = {
-	N_("git merge-base [-a | --all] <commit> <commit>..."),
-	N_("git merge-base [-a | --all] --octopus <commit>..."),
-	N_("git merge-base --independent <commit>..."),
-	N_("git merge-base --is-ancestor <commit> <commit>"),
-	N_("git merge-base --fork-point <ref> [<commit>]"),
+	N_("git merge-base [-a | --all] <ref> <ref>..."),
+	N_("git merge-base [-a | --all] --octopus <ref>..."),
+	N_("git merge-base --independent <ref>..."),
+	N_("git merge-base --is-ancestor <ref> <ref>"),
+	N_("git merge-base --fork-point <ref1> [<ref2>]"),
 	NULL
 };
 

@@ -158,7 +158,7 @@ int cmd_merge_base(int argc, const char **argv, const char *prefix)
 		OPT_CMDMODE(0, "is-ancestor", &cmdmode,
 			    N_("is the first one ancestor of the other?"), 'a'),
 		OPT_CMDMODE(0, "fork-point", &cmdmode,
-			    N_("find where <commit> forked from reflog of <ref>"), 'f'),
+			    N_("find where <ref2> forked from reflog of <ref1>"), 'f'),
 		OPT_END()
 	};
 

base-commit: 2d2118b814c11f509e1aa76cb07110f7231668dc

gitgitgadget

To me, this change goes too far in the opposite direction: Now it sounds like the command only accepts refs, when it actually accepts any "commit-ish"--i.e., anything that can be coerced to a commit. ("git worktree" uses this term in its usage for "add", for example.)

At the same time, it doesn't seem like this change goes far enough. "git merge"'s documentation, for example, is still using "<commit>". Why is it important that "git merge-base" mention refs, but not that "git merge" do so?

(Pardon the outburst from the peanut gallery)

Hi,

Maybe we can go for rev instead of ref?

Ciao,
Dscho

That's much better than 'ref', but I do not see why 'commit' is wrong in the first place. There are many ways to name an object, and rev is an old colloquial way to say "object name". Here, however, we want only commit objects, no?

Hi,

We do not only want commit objects. It is totally legitimate to ask

	git merge-base HEAD v2.25.0

(v2.25.0 is of course not a commit, it is a tag that _refers_ to a commit.)

Earlier, we would probably have called this a "commit-ish", but since users got so confused by this instance of Git Speak (is my interpretation of the reason, at least), we tend to call them "revs" these days.

I do think that the idea of the patch has merit, even if I agree with Bryan that we can probably improve on using "ref" instead of "commit".

Ciao,
Dscho

I meant to say (and was expecting those who know to know) committish, of course.

I am not among that "we". "rev" is an older and even more nerdy Git speak that was invented back when Linus was active, and as you can see, we used the word to mean not just commit or commit-ish, but anything that can be turned into an object name (you'd realize that you know it already, when you think about what 'rev' means in "git rev-parse"). The phrase *-ish came much later (I think I was among those who started it).

From: Takuya Noguchi <[email protected]>

The notation <commit> can be misunderstandable only for commit SHA1, but merge-base accepts any commit references. Like rev-parse, the name of arguments should be <rev> instead of <commit>.

---
doc: use 'rev' instead of 'commit' for merge-base arguments

The notation can be misunderstandable only for commit SHA1, but merge-base accepts any commit references. Like rev-parse, the name of arguments should be instead of .

Changes since v1:

* Use rev instead of ref, not commit-ish which is less used than rev through the document.

Published-As: https://github.com/gitgitgadget/git/releases/tag/pr-git-719%2Ftnir%2Fmerge-base-supporting-refs-v2
Fetch-It-Via: git fetch https://github.com/gitgitgadget/git pr-git-719/tnir/merge-base-supporting-refs-v2
Pull-Request: https://github.com/git/git/pull/719

Range-diff vs v1:

1: 9c83cf1c620 ! 1: 6e2157da4b1 doc: use 'ref' instead of 'commit' for merge-base arguments

     @@ -1,10 +1,10 @@
      Author: Takuya Noguchi <[email protected]>
      
     -    doc: use 'ref' instead of 'commit' for merge-base arguments
     +    doc: use 'rev' instead of 'commit' for merge-base arguments
      
          The notation <commit> can be misunderstandable only for commit SHA1,
     -    but merge-base accepts any commit references. Like reflog, the name of
     -    arguments should be <ref> instead of <commit>.
     +    but merge-base accepts any commit references. Like rev-parse, the name
     +    of arguments should be <rev> instead of <commit>.
      
          Signed-off-by: Takuya Noguchi <[email protected]>
      
     @@ -20,11 +20,11 @@
      -'git merge-base' --is-ancestor <commit> <commit>
      -'git merge-base' --independent <commit>...
      -'git merge-base' --fork-point <ref> [<commit>]
     -+'git merge-base' [-a|--all] <ref> <ref>...
     -+'git merge-base' [-a|--all] --octopus <ref>...
     -+'git merge-base' --is-ancestor <ref> <ref>
     -+'git merge-base' --independent <ref>...
     -+'git merge-base' --fork-point <ref> [<ref>]
     ++'git merge-base' [-a|--all] <rev> <rev>...
     ++'git merge-base' [-a|--all] --octopus <rev>...
     ++'git merge-base' --is-ancestor <rev> <rev>
     ++'git merge-base' --independent <rev>...
     ++'git merge-base' --fork-point <ref> [<rev>]
       
       DESCRIPTION
       -----------
     @@ -41,11 +41,11 @@
      -	N_("git merge-base --independent <commit>..."),
      -	N_("git merge-base --is-ancestor <commit> <commit>"),
      -	N_("git merge-base --fork-point <ref> [<commit>]"),
     -+	N_("git merge-base [-a | --all] <ref> <ref>..."),
     -+	N_("git merge-base [-a | --all] --octopus <ref>..."),
     -+	N_("git merge-base --independent <ref>..."),
     -+	N_("git merge-base --is-ancestor <ref> <ref>"),
     -+	N_("git merge-base --fork-point <ref1> [<ref2>]"),
     ++	N_("git merge-base [-a | --all] <rev> <rev>..."),
     ++	N_("git merge-base [-a | --all] --octopus <rev>..."),
     ++	N_("git merge-base --independent <rev>..."),
     ++	N_("git merge-base --is-ancestor <rev> <rev>"),
     ++	N_("git merge-base --fork-point <ref> [<rev>]"),
       	NULL
       };
       
     @@ -54,7 +54,7 @@
       			    N_("is the first one ancestor of the other?"), 'a'),
       		OPT_CMDMODE(0, "fork-point", &cmdmode,
      -			    N_("find where <commit> forked from reflog of <ref>"), 'f'),
     -+			    N_("find where <ref2> forked from reflog of <ref1>"), 'f'),
     ++			    N_("find where <rev> forked from reflog of <ref>"), 'f'),
       		OPT_END()
       	};

 Documentation/git-merge-base.txt | 10 +++++-----
 builtin/merge-base.c             | 12 ++++++------
 2 files changed, 11 insertions(+), 11 deletions(-)

index 2d944e0851f..60438a00871 100644
@@ -9,11 +9,11 @@ git-merge-base - Find as good common ancestors as possible for a merge
 SYNOPSIS
 --------
 [verse]
-'git merge-base' [-a|--all] <commit> <commit>...
-'git merge-base' [-a|--all] --octopus <commit>...
-'git merge-base' --is-ancestor <commit> <commit>
-'git merge-base' --independent <commit>...
-'git merge-base' --fork-point <ref> [<commit>]
+'git merge-base' [-a|--all] <rev> <rev>...
+'git merge-base' [-a|--all] --octopus <rev>...
+'git merge-base' --is-ancestor <rev> <rev>
+'git merge-base' --independent <rev>...
+'git merge-base' --fork-point <ref> [<rev>]
 
 DESCRIPTION
 -----------

index e3f8da13b69..e03f2269e88 100644
@@ -29,11 +29,11 @@ static int show_merge_base(struct commit **rev, int rev_nr, int show_all)
 }
 
 static const char * const merge_base_usage[] = {
-	N_("git merge-base [-a | --all] <commit> <commit>..."),
-	N_("git merge-base [-a | --all] --octopus <commit>..."),
-	N_("git merge-base --independent <commit>..."),
-	N_("git merge-base --is-ancestor <commit> <commit>"),
-	N_("git merge-base --fork-point <ref> [<commit>]"),
+	N_("git merge-base [-a | --all] <rev> <rev>..."),
+	N_("git merge-base [-a | --all] --octopus <rev>..."),
+	N_("git merge-base --independent <rev>..."),
+	N_("git merge-base --is-ancestor <rev> <rev>"),
+	N_("git merge-base --fork-point <ref> [<rev>]"),
 	NULL
 };
 

@@ -158,7 +158,7 @@ int cmd_merge_base(int argc, const char **argv, const char *prefix)
 		OPT_CMDMODE(0, "is-ancestor", &cmdmode,
 			    N_("is the first one ancestor of the other?"), 'a'),
 		OPT_CMDMODE(0, "fork-point", &cmdmode,
-			    N_("find where <commit> forked from reflog of <ref>"), 'f'),
+			    N_("find where <rev> forked from reflog of <ref>"), 'f'),
 		OPT_END()
 	};
 

base-commit: 2f268890c2cd2f115424936bbee27f8269080e5e

gitgitgadget

Let's step back a bit. When our documentation says

    $ git log <commit>

we expect that the readers to understand that all of the following are accepted:

    $ git log master
    $ git log master~10
    $ git log 3868ac720f
    $ git log 3868ac720f7a26f3241f43764d0dc790ec55238f

What gave you the impression that only the last one is valid? We need to fix _that_.

The side discussion we had with Dscho touched another important point (i.e. when a command wants to take a commit but a user gives it a tag that points at a commit, the command almost always accepts the tag, finds the commit the tag points at, and uses that commit instead of the tag---we often mark such a parameter that expects commit but does not have to name a commit object <commit-ish>), but it is more or less orthogonal. All of these are accepted,

    $ git log v2.25.0
    $ git log 61e952148
    $ git log 61e9521487999585dc2b8f27c2a65226fb531a07

not just the last one.

And "like rev-parse" is a poor justification. It is a lowest-level command that was written in dark ages, and the language used in the documentation hasn't been updated to more modern terms. Back then, we said "revision" (and "rev" is a short for it) and the term was invented to mean commit (see "$ git help glossary") but was used loosely and more-or-less interchangeably with "object name" (in other words, when the speaker who said "rev" did not necessarily mean to limit the reference to commits, the word did not limit itself to commit-ish but also covered trees and blobs).

Now, in the context of "git rev-parse",

    $ git rev-parse eacd13fab7e3

does make sense. It is OK to give it a short version of a tree object name (it is the tree of the commit pointed by the v2.25.0 release), so "git rev-parse <object-name>" (or "git rev-parse <rev>") would be OK.

It is however a poor example to base our decision on how to explain merge-base. The command wants to _use_ two (or more) commits to work on, so like many other commands, when it is fed a tag, it tries to see if it points at a commit (and barfs if it does not) and use that commit instead. In other words, it takes commit-ish.

Saying that it takes <commit> is *not* so bad, but changing it to <rev> is a move backwards, I'd have to say.

Thanks for working on it, but s/ref/rev/ is not a good change.

A side note I forgot to add. A few commands take both commit and tag but want to do different things depending on the kind of object they get, and for them, <commit> and <commit-ish> should be used carefully in the documentation.

For example, "git cat-file commit v2.25.0" and "git cat-file tag v2.25.0" do two different things. They should be described as

	$ git cat-file commit <commit-ish>
	$ git cat-file tag <tag>

"git merge <commit>" and "git merge <tag>" do different things, even though <tag> must be a <commit-ish>.

But most of the Git subcommands (including the "cat-file commit" case) peel a tag as needed, so these special cases are minority.