templatekw: choose {latesttag} by len(changes), not date (
issue5659)
As Augie reported in the bug, the current heuristic of choosing the
best tag of a merge commit by taking the one with newest tag (in terms
of tagging date) currently fails in the Mercurial repo itself. Copying
the example from Yuya:
$ hg glog -T '{node|short} {latesttag}+{latesttagdistance}\n' \
-r '4.2.3: & (merge() + parents(merge()) + tag())'
o
02a745c20121 4.2.3+5
|\
| o
86aca74a063b 4.2.3+4
| |\
| | o
e6d8ee3c9ec3 4.3-rc+109
| | |
| | ~
o |
a3ce07e2dde5 4.3.1+2
: |
o |
3fee7f7d2da0 4.3.1+0
|/
o
98e990bb7330 4.2.3+3
|\
| ~
o
506d7e48fbe6 4.2.3+2
:
o
943c91326b23 4.2.3+0
|
~
It seems to me like the best choice is the tag with the smallest
number of changes since it (across all paths, not the longest single
path). So that's what this patch does, even though it's
costly. Best-of-5 timings for Yuya's command above shows a slowdown
from 1.293s to 1.610s. We can optimize it later.
Differential Revision: https://phab.mercurial-scm.org/D447
$ hg init base
$ cd base
$ echo 'alpha' > alpha
$ hg ci -A -m 'add alpha'
adding alpha
$ cd ..
$ hg clone base work
updating to branch default
1 files updated, 0 files merged, 0 files removed, 0 files unresolved
$ cd work
$ echo 'beta' > beta
$ hg ci -A -m 'add beta'
adding beta
$ cd ..
$ cd base
$ echo 'gamma' > gamma
$ hg ci -A -m 'add gamma'
adding gamma
$ cd ..
$ cd work
$ hg pull -q
$ hg merge
1 files updated, 0 files merged, 0 files removed, 0 files unresolved
(branch merge, don't forget to commit)
Update --clean to revision 1 to simulate a failed merge:
$ rm alpha beta gamma
$ hg update --clean 1
2 files updated, 0 files merged, 0 files removed, 0 files unresolved
$ cd ..