extensions: refuse to load extensions if minimum hg version not met
As the author of several 3rd party extensions, I frequently see bug
reports from users attempting to run my extension with an old version
of Mercurial that I no longer support in my extension. Oftentimes, the
extension will import just fine. But as soon as we run extsetup(),
reposetup(), or get into the guts of a wrapped function, we encounter
an exception and abort. Today, Mercurial will print a message about
extensions that don't have a "testedwith" declaring explicit
compatibility with the current version.
The existing mechanism is a good start. But it isn't as robust as I
would like. Specifically, Mercurial assumes compatibility by default.
This means extension authors must perform compatibility checking in
their extsetup() or we wait and see if we encounter an abort at
runtime. And, compatibility checking can involve a lot of code and
lots of error checking. It's a lot of effort for extension authors.
Oftentimes, extension authors know which versions of Mercurial there
extension works on and more importantly where it is broken.
This patch introduces a magic "minimumhgversion" attribute in
extensions. When found, the extension loading mechanism will compare
the declared version against the current Mercurial version. If the
extension explicitly states we require a newer Mercurial version, a
warning is printed and the extension isn't loaded beyond importing
the Python module. This causes a graceful failure while alerting
the user of the compatibility issue.
I would be receptive to the idea of making the failure more fatal.
However, care would need to be taken to not criple every hg command.
e.g. the user may use `hg config` to fix the hgrc and if we aborted
trying to run that, the user would effectively be locked out of `hg`!
A potential future improvement to this functionality would be to catch
ImportError for the extension/module and parse the source code for
"minimumhgversion = 'XXX'" and do similar checking. This way we could
give more information about why the extension failed to load.
#require svn svn-bindings
$ cat >> $HGRCPATH <<EOF
> [extensions]
> convert =
> EOF
$ svnadmin create svn-repo
$ svnadmin load -q svn-repo < "$TESTDIR/svn/branches.svndump"
Convert trunk and branches
$ cat > branchmap <<EOF
> old3 newbranch
>
>
> EOF
$ hg convert --branchmap=branchmap --datesort -r 10 svn-repo A-hg
initializing destination A-hg repository
scanning source...
sorting...
converting...
10 init projA
9 hello
8 branch trunk, remove c and dir
7 change a
6 change b
5 move and update c
4 move and update c
3 change b again
2 move to old2
1 move back to old
0 last change to a
Test template keywords
$ hg -R A-hg log --template '{rev} {svnuuid}{svnpath}@{svnrev}\n'
10 644ede6c-2b81-4367-9dc8-d786514f2cde/trunk@10
9 644ede6c-2b81-4367-9dc8-d786514f2cde/branches/old@9
8 644ede6c-2b81-4367-9dc8-d786514f2cde/branches/old2@8
7 644ede6c-2b81-4367-9dc8-d786514f2cde/branches/old@7
6 644ede6c-2b81-4367-9dc8-d786514f2cde/trunk@6
5 644ede6c-2b81-4367-9dc8-d786514f2cde/branches/old@6
4 644ede6c-2b81-4367-9dc8-d786514f2cde/branches/old@5
3 644ede6c-2b81-4367-9dc8-d786514f2cde/trunk@4
2 644ede6c-2b81-4367-9dc8-d786514f2cde/branches/old@3
1 644ede6c-2b81-4367-9dc8-d786514f2cde/trunk@2
0 644ede6c-2b81-4367-9dc8-d786514f2cde/trunk@1
Convert again
$ hg convert --branchmap=branchmap --datesort svn-repo A-hg
scanning source...
sorting...
converting...
0 branch trunk@1 into old3
$ cd A-hg
$ hg log -G --template 'branch={branches} {rev} {desc|firstline} files: {files}\n'
o branch=newbranch 11 branch trunk@1 into old3 files:
|
| o branch= 10 last change to a files: a
| |
| | o branch=old 9 move back to old files:
| | |
| | o branch=old2 8 move to old2 files:
| | |
| | o branch=old 7 change b again files: b
| | |
| o | branch= 6 move and update c files: b
| | |
| | o branch=old 5 move and update c files: c
| | |
| | o branch=old 4 change b files: b
| | |
| o | branch= 3 change a files: a
| | |
| | o branch=old 2 branch trunk, remove c and dir files: c
| |/
| o branch= 1 hello files: a b c dir/e
|/
o branch= 0 init projA files:
$ hg branches
newbranch 11:a6d7cc050ad1
default 10:6e2b33404495
old 9:93c4b0f99529
old2 8:b52884d7bead (inactive)
$ hg tags -q
tip
$ cd ..
Test hg failing to call itself
$ HG=foobar hg convert svn-repo B-hg 2>&1 | grep abort
abort: Mercurial failed to run itself, check hg executable is in PATH
Convert 'trunk' to branch other than 'default'
$ cat > branchmap <<EOF
> default hgtrunk
>
>
> EOF
$ hg convert --branchmap=branchmap --datesort -r 10 svn-repo C-hg
initializing destination C-hg repository
scanning source...
sorting...
converting...
10 init projA
9 hello
8 branch trunk, remove c and dir
7 change a
6 change b
5 move and update c
4 move and update c
3 change b again
2 move to old2
1 move back to old
0 last change to a
$ cd C-hg
$ hg branches --template '{branch}\n'
hgtrunk
old
old2
$ cd ..