simplemerge: stop merging file flags
As
384df4db6520 (merge: merge file flags together with file content,
2013-01-09) explains, we shouldn't do a 3-way merge of the
symlink. However, since
84614212ae39 (flags: actually merge flags in
simplemerge, 2020-05-16), we do that in
`simplemerge.simplemerge()`. What's more, the merging of the
executable flag there isn't actually necessary; it was made a no-op by
the very next commit, i.e.
4234c9af515d (flags: read flag from
dirstate/disk for workingcopyctx (
issue5743), 2020-05-16).
I found the overall flag-merging code (not the bit in
`simplemerge.py`) very hard to follow, but I think I now finally
understand how it works. `mergestate.resolve()` calculates the merged
file flags and sets them on the local side of the merge (confusingly
by calling `_restore_backup()`). Then it calls
`filemerge.filemerge()`, which in turn calls
`simplemerge.simplemerge()` (if premerge is enabled). That means that
the flags on the local side `fcs.flags()` are already correct when the
flag-merging code in `simplemerge.simplemerge()` runs. Interestingly,
that code still works when the local side already has the merged
value, it just doesn't change the value. Here's a truth table to
explain why:
```
BLOMCAR
0000000
0011111
0101011
0111111
1000000
1010000
1100000
1111101
```
B: Base
L: Local
O: Other
M: Merged flags from `mergestate.resolve()`, i.e. what's called "local"
when we get to `simplemerge.simplemerge()`
C: `commonflags` in `simplemerge.simplemerge()`, i.e. `M & O`
A: `addedflags` in `simplemerge.simplemerge()`, i.e. `(M ^ O) - B`
R: Re-merged flags `simplemerge.simplemerge()`, i.e. `C | A`
As you can see, the re-merged flags are always unchanged compared to
the initial merged flags (R equals M).
Therefore, this patch effectively backs out
84614212ae39. (I might
later refactor this code to have the flags explicitly passed in.)
`simplemerge.simplemerge()` is also called from
`contrib/simplemerge.py`, but that code never passes any flags.
Differential Revision: https://phab.mercurial-scm.org/D11879
https://bz.mercurial-scm.org/1306
Initialize remote repo with branches:
$ hg init remote
$ cd remote
$ echo a > a
$ hg ci -Ama
adding a
$ hg branch br
marked working directory as branch br
(branches are permanent and global, did you want a bookmark?)
$ hg ci -Amb
$ echo c > c
$ hg ci -Amc
adding c
$ hg log
changeset: 2:ae3d9c30ec50
branch: br
tag: tip
user: test
date: Thu Jan 01 00:00:00 1970 +0000
summary: c
changeset: 1:3f7f930ca414
branch: br
user: test
date: Thu Jan 01 00:00:00 1970 +0000
summary: b
changeset: 0:cb9a9f314b8b
user: test
date: Thu Jan 01 00:00:00 1970 +0000
summary: a
$ cd ..
Try cloning -r branch:
$ hg clone -rbr remote local1
adding changesets
adding manifests
adding file changes
added 3 changesets with 2 changes to 2 files
new changesets cb9a9f314b8b:ae3d9c30ec50
updating to branch br
2 files updated, 0 files merged, 0 files removed, 0 files unresolved
$ hg -R local1 parents
changeset: 2:ae3d9c30ec50
branch: br
tag: tip
user: test
date: Thu Jan 01 00:00:00 1970 +0000
summary: c
Try cloning -rother clone#branch:
$ hg clone -r0 remote#br local2
adding changesets
adding manifests
adding file changes
added 3 changesets with 2 changes to 2 files
new changesets cb9a9f314b8b:ae3d9c30ec50
updating to branch default
1 files updated, 0 files merged, 0 files removed, 0 files unresolved
$ hg -R local2 parents
changeset: 0:cb9a9f314b8b
user: test
date: Thu Jan 01 00:00:00 1970 +0000
summary: a
Try cloning -r1 clone#branch:
$ hg clone -r1 remote#br local3
adding changesets
adding manifests
adding file changes
added 3 changesets with 2 changes to 2 files
new changesets cb9a9f314b8b:ae3d9c30ec50
updating to branch br
1 files updated, 0 files merged, 0 files removed, 0 files unresolved
$ hg -R local3 parents
changeset: 1:3f7f930ca414
branch: br
user: test
date: Thu Jan 01 00:00:00 1970 +0000
summary: b