Re: git bugs

From: Shawn O. Pearce <spearce@spearce.org>
Date: Jun 12, 2008, 03:17 UTC
Message-ID: <20080612031723.GJ11793@spearce.org>
In-Reply-To: <832adb090806100141n69c086a2v2f59fe94b2f4ead3@mail.gmail.com>

Ben Lynn <benlynn@gmail.com> wrote:

Show 8 quoted lines

> 1. The import/export language poorly handles distinct initial commits
> on the same branch, because given two commits with same branch name,
> it assumes the latter is the descendant of the former (if there are no
> "from" commands).
> 
> Normally this is what you want. But if your project, like git, ever
> merges distinct initial commits, then all but the first will
> unexpectedly gain parents, corrupting all their descendants' hashes.

...

> As a workaround, I have a custom importer that knows that
> git-fast-export omits the "from" command in initial commits. But there
> should be a command to specify that the current commit is an initial
> commit, allowing reliable export of projects such as git.

fast-export is wrong, and is using the language wrong. fast-import is correct. Because I said so. :-)

No, seriously, fast-import came along first and can describe what you are referring to as the many initial root commits in git.git. The issue is fast-export is not generating commands to say as much.

Its quite easily fixable.

When we output a commit in handle_commit() we just need to reset the branch if we have no parents. That simple. This is totally untested, but I think it fixes it.

diff --git a/builtin-fast-export.c b/builtin-fast-export.c
index 1dfc01e..d0a462f 100644
--- a/builtin-fast-export.c
+++ b/builtin-fast-export.c
@@ -188,6 +188,8 @@ static void handle_commit(struct commit *commit, struct rev_info *rev)
 	mark_object(&commit->object);
 	if (!is_encoding_utf8(encoding))
 		reencoded = reencode_string(message, "UTF-8", encoding);
+	if (!commit->parents)
+		printf("reset %s\n", (const char*)commit->util);
 	printf("commit %s\nmark :%d\n%.*s\n%.*s\ndata %u\n%s",
 	       (const char *)commit->util, last_idnum,
 	       (int)(author_end - author), author,

-- 
Shawn.