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Re: Bug: "git checkout -b" should be allowed in empty repo

From
Junio C Hamano <gitster@pobox.com>
Date
Jan 30, 2012, 18:48 UTC
Message-ID
<7v39axc9gp.fsf@alter.siamese.dyndns.org>
In-Reply-To
<4F263AEE.4080409@alum.mit.edu>
Michael Haggerty <mhagger@alum.mit.edu> writes:
Show 5 quoted lines
> [3] If commit 0000000 were treated specially, then there would be no
> unborn branches but only branches pointing at the empty commit.  In that
> case, my expectation would change--the old branch should be left
> pointing at 0000000.  But currently git has no concept of an unborn
> branch that is not HEAD.

And it probably is not a good thing to add such. Under that constraints, HEAD that says refs/heads/foo where foo does not exist yet needs to be special cased at places where it matters.

For that matter, even if we artificially created refs/heads/foo before any commit is made and made it point at 0{40}, you would need to add special cases to other parts of the system (e.g. "commit" needs to notice that the result should be a root, not a child of 0{40}; "checkout other_branch" needs to notice that it should refrain from running the equivalent of "read-tree -m HEAD other_branch" because HEAD does not point at a real tree; etc.), so it does not change the fact that the unborn branch is case is special.

Note that I am not saying that we shouldn't add support for special cases with special case codepaths.

Perhaps we would need to sprinkle more special case magic like this (this is for the special case that arises from the same cause)?

 builtin/branch.c |    7 +++++++
 1 files changed, 7 insertions(+), 0 deletions(-)
diff --git a/builtin/branch.c b/builtin/branch.c
index 7095718..0997e75 100644
--- a/builtin/branch.c
+++ b/builtin/branch.c
@@ -640,6 +640,13 @@ static int edit_branch_description(const char *branch_name)
 	struct strbuf buf = STRBUF_INIT;
 	struct strbuf name = STRBUF_INIT;
 
+	strbuf_addf(&name, "refs/heads/%s", branch_name);
+	if (!ref_exists(name.buf)) {
+		strbuf_reset(&name);
+		return error("No such branch '%s'.", branch_name);
+	}
+	strbuf_reset(&name);
+
 	read_branch_desc(&buf, branch_name);
 	if (!buf.len || buf.buf[buf.len-1] != '\n')
 		strbuf_addch(&buf, '\n');
Previous: Michael HaggertyNext: Junio C Hamano
Message 5 of 34 in “Bug: "git checkout -b" should be allowed in empty repo”
  1. Michael HaggertyJan 29, 2012
  2. Junio C HamanoJan 29, 2012
  3. Junio C HamanoJan 29, 2012
  4. Michael HaggertyJan 30, 2012
  5. Junio C HamanoJan 30, 2012
  6. Junio C HamanoJan 30, 2012
  7. Jeff KingJan 30, 2012
  8. Junio C HamanoFeb 6, 2012
  9. Junio C HamanoFeb 6, 2012
  10. Jeff KingFeb 6, 2012
  11. Andrew ArdillFeb 6, 2012
  12. Jeff KingFeb 6, 2012
  13. Michael HaggertyFeb 6, 2012
  14. Jeff KingFeb 6, 2012
  15. Junio C HamanoFeb 6, 2012
  16. Jeff KingFeb 6, 2012
  17. Michael HaggertyFeb 7, 2012
  18. demerphqFeb 6, 2012
  19. Junio C HamanoFeb 6, 2012
  20. Jeff KingFeb 6, 2012
  21. Junio C HamanoFeb 6, 2012
  22. Junio C HamanoFeb 6, 2012
  23. Jeff KingFeb 6, 2012
  24. Michael HaggertyFeb 6, 2012
  25. Junio C HamanoFeb 6, 2012
  26. Jeff KingJan 30, 2012
  27. branch --edit-description: protect against mistyped branch nameJunio C Hamano, Feb 6, 2012
  28. Junio C HamanoFeb 6, 2012
  29. Jeff KingFeb 6, 2012
  30. Michael HaggertyJan 31, 2012
  31. Johannes SixtJan 31, 2012
  32. demerphqJan 31, 2012
  33. Jakub NarebskiJan 31, 2012
  34. Michael HaggertyJan 31, 2012

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