Question

I’m setting up a Mercurial repository to track third-party code, roughly following the vendor-default branch scheme described in Rudi’s answer to this question. In order to quickly retrieve a particular version, I create tags for each vendor and default version.

I initialize the repo by committing an empty .hgtags to establish the default branch, then I hg branch vendor and import the first version. The process to add a new version looks like this:

hg up -C vendor
... load new version ...
hg commit -A -m "Adding version x.y.x"
hg tag vendor-x.y.z
hg up -C default
hg merge vendor
hg commit -m "Merging version x.y.z"
hg tag x.y.z

During the merge I always keep the local copy of .hgtags, so the result is that the vendor branch has .hgtags containing all the vendor-x.y.z tags while the default branch .hgtags has only the x.y.z tags.

It’s my understanding that Mercurial considers .hgtags from all heads when working with tags. Yet when I run hg tags the result contains only tip and the x.y.z tags. This is the same regardless of which branch my working directory is updated to; it’s always the tags from the default branch .hgtags file.

I can update to the vendor-x.y.z tags, so Mercurial does see their existence, but the update appears to give me code from the vendor branch tip. The x.y.z tags work fine.

I’ve worked mainly with Git and SVN/CVS in the past, so I assume that this is a problem of understanding, not a technical issue. I did try it, just in case, on two versions of Mercurial (2.0.2 and 2.3.2) and got the same results.

Answer 1

I’m not in front of my Mercurial system to verify, but I think the issue is Mercurial only considers .hgtags from topological heads, not branch heads. Example:

[1]---[2]---[5]---[6]    Default
        \         /
         [3]---[4]       Vendor

[6] is a topological head, [4] and [6] are branch heads. The solution is to keep all changes to .hgtags on a merge.

Edit

Here’s my test. Directly after the merge I accepted the local .hgtags and hg tags only displays the tag on default. I can’t update to the vendor tag, which differs from what you are seeing. I’m using Mercurial 2.3.1. After creating another changeset on vendor and making a second topological head, the missing tag reappears.

hg init test
cd test
echo >a
hg ci -Am 1
hg branch vendor
echo >b
hg ci -Am 2
hg tag v1
hg update default
hg tag d1
hg merge vendor --tool internal:local
hg ci -m Merge

@REM This only shows 'tip' and 'd1'
hg tags

hg update vendor
hg tags
hg update d1

@REM This fails to update.
hg update v1

@ Add another topological head by committing to vendor
hg update vendor
echo >c
hg ci -Am 3

@ Now all tags are visible and work.
hg tags
hg update v1
hg update d1

And the output:

C:\>hg init test
C:\>cd test
C:\test>echo  1>a
C:\test>hg ci -Am 1
adding a
C:\test>hg branch vendor
marked working directory as branch vendor
(branches are permanent and global, did you want a bookmark?)
C:\test>echo  1>b
C:\test>hg ci -Am 2
adding b
C:\test>hg tag v1
C:\test>hg update default
0 files updated, 0 files merged, 2 files removed, 0 files unresolved
C:\test>hg tag d1
C:\test>hg merge vendor --tool internal:local
1 files updated, 1 files merged, 0 files removed, 0 files unresolved
(branch merge, don't forget to commit)
C:\test>hg ci -m Merge
C:\test>hg tags
tip                                4:80759c41b3cc
d1                                 0:17b05ed457d1
C:\test>hg update vendor
1 files updated, 0 files merged, 0 files removed, 0 files unresolved
C:\test>hg tags
tip                                4:80759c41b3cc
d1                                 0:17b05ed457d1
C:\test>hg update d1
0 files updated, 0 files merged, 2 files removed, 0 files unresolved
C:\test>hg update v1
abort: unknown revision 'v1'!
C:\test>hg update vendor
2 files updated, 0 files merged, 0 files removed, 0 files unresolved
C:\test>echo  1>c
C:\test>hg ci -Am 3
adding c
C:\test>hg tags
tip                                5:a2c0fe73a9f1
v1                                 1:3168d0f4e5e5
d1                                 0:17b05ed457d1
C:\test>hg update v1
0 files updated, 0 files merged, 2 files removed, 0 files unresolved
C:\test>hg update d1
0 files updated, 0 files merged, 1 files removed, 0 files unresolved