view tests/test-rebase-abort.t @ 35569:964212780daf

rust: implementation of `hg`

This commit provides a mostly-working implementation of the
`hg` script in Rust along with scaffolding to support Rust in
the repository.

If you are familiar with Rust, the contents of the added rust/
directory should be pretty straightforward. We create an "hgcli"
package that implements a binary application to run Mercurial.
The output of this package is an "hg" binary.

Our Rust `hg` (henceforth "rhg") essentially is a port of the existing
`hg` Python script. The main difference is the creation of the embedded
CPython interpreter is handled by the binary itself instead of relying
on the shebang. In that sense, rhg is more similar to the "exe wrapper"
we currently use on Windows. However, unlike the exe wrapper, rhg does
not call the `hg` Python script. Instead, it uses the CPython APIs to
import mercurial modules and call appropriate functions. The amount of
code here is surprisingly small.

It is my intent to replace the existing C-based exe wrapper with rhg.
Preferably in the next Mercurial release. This should be achievable -
at least for some Mercurial distributions. The future/timeline for
rhg on other platforms is less clear. We already ship a hg.exe on
Windows. So if we get the quirks with Rust worked out, shipping a
Rust-based hg.exe should hopefully not be too contentious.

Now onto the implementation.

We're using python27-sys and the cpython crates for talking to the
CPython API. We currently don't use too much functionality of the
cpython crate and could have probably cut it out. However, it does
provide a reasonable abstraction over unsafe {} CPython function
calls. While we still have our fair share of those, at least we're
not dealing with too much refcounting, error checking, etc. So I
think the use of the cpython crate is justified. Plus, there is
not-yet-implemented functionality that could benefit from cpython. I
see our use of this crate only increasing.

The cpython and python27-sys crates are not without their issues.
The cpython crate didn't seem to account for the embedding use case
in its design. Instead, it seems to assume that you are building
a Python extension. It is making some questionable decisions around
certain CPython APIs. For example, it insists that
PyEval_ThreadsInitialized() is called and that the Python code
likely isn't the main thread in the underlying application. It
is also missing some functionality that is important for embedded
use cases (such as exporting the path to the Python interpreter
from its build script). After spending several hours trying to
wrangle python27-sys and cpython, I gave up and forked the project
on GitHub. Our Cargo.toml tracks this fork. I'm optimistic that
the upstream project will accept our contributions and we can
eventually unfork.

There is a non-trivial amount of code in our custom Cargo build
script. Our build.rs (which is called as part of building the hgcli
crate):

* Validates that the Python interpreter that was detected by the
  python27-sys crate provides a shared library (we only support
  shared library linking at this time - although this restriction
  could be loosened).
* Validates that the Python is built with UCS-4 support. This ensures
  maximum Unicode compatibility.
* Exports variables to the crate build allowing the built crate to e.g.
  find the path to the Python interpreter.

The produced rhg should be considered alpha quality. There are several
known deficiencies. Many of these are documented with inline TODOs.

Probably the biggest limitation of rhg is that it assumes it is
running from the ./rust/target/<target> directory of a source
distribution. So, rhg is currently not very practical for real-world
use. But, if you can `cargo build` it, running the binary *should*
yield a working Mercurial CLI.

In order to support using rhg with the test harness, we needed to hack
up run-tests.py so the path to Mercurial's Python files is set properly.
The change is extremely hacky and is only intended to be a stop-gap
until the test harness gains first-class support for installing rhg.
This will likely occur after we support running rhg outside the
source directory.

Despite its officially alpha quality, rhg copes extremely well with
the test harness (at least on Linux). Using
`run-tests.py --with-hg ../rust/target/debug/hg`, I only encounter
the following failures:

* test-run-tests.t -- Warnings emitted about using an unexpected
  Mercurial library. This is due to the hacky nature of setting the
  Python directory when run-tests.py detected rhg.
* test-devel-warnings.t -- Expected stack trace missing frame for `hg`
  (This is expected since we no longer have an `hg` script!)
* test-convert.t -- Test running `$PYTHON "$BINDIR"/hg`, which obviously
  assumes `hg` is a Python script.
* test-merge-tools.t -- Same assumption about `hg` being executable with
  Python.
* test-http-bad-server.t -- Seeing exit code 255 instead of 1 around
  line 358.
* test-blackbox.t -- Exit code 255 instead of 1.
* test-basic.t -- Exit code 255 instead of 1.

It certainly looks like we have a bug around exit code handling. I
don't think it is severe enough to hold up review and landing of this
initial implementation. Perfect is the enemy of good.

Differential Revision: https://phab.mercurial-scm.org/D1581

  $ cat >> $HGRCPATH <<EOF
  > [extensions]
  > rebase=
  > 
  > [phases]
  > publish=False
  > 
  > [alias]
  > tglog = log -G --template "{rev}:{phase} '{desc}' {branches}\n"
  > EOF


  $ hg init a
  $ cd a

  $ touch .hg/rebasestate
  $ hg sum
  parent: -1:000000000000 tip (empty repository)
  branch: default
  commit: (clean)
  update: (current)
  abort: .hg/rebasestate is incomplete
  [255]
  $ rm .hg/rebasestate

  $ echo c1 > common
  $ hg add common
  $ hg ci -m C1

  $ echo c2 >> common
  $ hg ci -m C2

  $ echo c3 >> common
  $ hg ci -m C3

  $ hg up -q -C 1

  $ echo l1 >> extra
  $ hg add extra
  $ hg ci -m L1
  created new head

  $ sed -e 's/c2/l2/' common > common.new
  $ mv common.new common
  $ hg ci -m L2

  $ hg phase --force --secret 2

  $ hg tglog
  @  4:draft 'L2'
  |
  o  3:draft 'L1'
  |
  | o  2:secret 'C3'
  |/
  o  1:draft 'C2'
  |
  o  0:draft 'C1'
  

Conflicting rebase:

  $ hg rebase -s 3 -d 2
  rebasing 3:3163e20567cc "L1"
  rebasing 4:46f0b057b5c0 "L2" (tip)
  merging common
  warning: conflicts while merging common! (edit, then use 'hg resolve --mark')
  unresolved conflicts (see hg resolve, then hg rebase --continue)
  [1]

Insert unsupported advisory merge record:

  $ hg --config extensions.fakemergerecord=$TESTDIR/fakemergerecord.py fakemergerecord -x
  $ hg debugmergestate
  * version 2 records
  local: 3e046f2ecedb793b97ed32108086edd1a162f8bc
  other: 46f0b057b5c061d276b91491c22151f78698abd2
  labels:
    local: dest
    other: source
  unrecognized entry: x	advisory record
  file extras: common (ancestorlinknode = 3163e20567cc93074fbb7a53c8b93312e59dbf2c)
  file: common (record type "F", state "u", hash 94c8c21d08740f5da9eaa38d1f175c592692f0d1)
    local path: common (flags "")
    ancestor path: common (node de0a666fdd9c1a0b0698b90d85064d8bd34f74b6)
    other path: common (node 2f6411de53677f6f1048fef5bf888d67a342e0a5)
  $ hg resolve -l
  U common

Insert unsupported mandatory merge record:

  $ hg --config extensions.fakemergerecord=$TESTDIR/fakemergerecord.py fakemergerecord -X
  $ hg debugmergestate
  * version 2 records
  local: 3e046f2ecedb793b97ed32108086edd1a162f8bc
  other: 46f0b057b5c061d276b91491c22151f78698abd2
  labels:
    local: dest
    other: source
  file extras: common (ancestorlinknode = 3163e20567cc93074fbb7a53c8b93312e59dbf2c)
  file: common (record type "F", state "u", hash 94c8c21d08740f5da9eaa38d1f175c592692f0d1)
    local path: common (flags "")
    ancestor path: common (node de0a666fdd9c1a0b0698b90d85064d8bd34f74b6)
    other path: common (node 2f6411de53677f6f1048fef5bf888d67a342e0a5)
  unrecognized entry: X	mandatory record
  $ hg resolve -l
  abort: unsupported merge state records: X
  (see https://mercurial-scm.org/wiki/MergeStateRecords for more information)
  [255]
  $ hg resolve -ma
  abort: unsupported merge state records: X
  (see https://mercurial-scm.org/wiki/MergeStateRecords for more information)
  [255]

Abort (should clear out unsupported merge state):

  $ hg rebase --abort
  saved backup bundle to $TESTTMP/a/.hg/strip-backup/3e046f2ecedb-6beef7d5-backup.hg
  rebase aborted
  $ hg debugmergestate
  no merge state found

  $ hg tglog
  @  4:draft 'L2'
  |
  o  3:draft 'L1'
  |
  | o  2:secret 'C3'
  |/
  o  1:draft 'C2'
  |
  o  0:draft 'C1'
  
Test safety for inconsistent rebase state, which may be created (and
forgotten) by Mercurial earlier than 2.7. This emulates Mercurial
earlier than 2.7 by renaming ".hg/rebasestate" temporarily.

  $ hg rebase -s 3 -d 2
  rebasing 3:3163e20567cc "L1"
  rebasing 4:46f0b057b5c0 "L2" (tip)
  merging common
  warning: conflicts while merging common! (edit, then use 'hg resolve --mark')
  unresolved conflicts (see hg resolve, then hg rebase --continue)
  [1]

  $ mv .hg/rebasestate .hg/rebasestate.back
  $ hg update --quiet --clean 2
  $ hg --config extensions.mq= strip --quiet "destination()"
  $ mv .hg/rebasestate.back .hg/rebasestate

  $ hg rebase --continue
  abort: cannot continue inconsistent rebase
  (use "hg rebase --abort" to clear broken state)
  [255]
  $ hg summary | grep '^rebase: '
  rebase: (use "hg rebase --abort" to clear broken state)
  $ hg rebase --abort
  rebase aborted (no revision is removed, only broken state is cleared)

  $ cd ..


Construct new repo:

  $ hg init b
  $ cd b

  $ echo a > a
  $ hg ci -Am A
  adding a

  $ echo b > b
  $ hg ci -Am B
  adding b

  $ echo c > c
  $ hg ci -Am C
  adding c

  $ hg up -q 0

  $ echo b > b
  $ hg ci -Am 'B bis'
  adding b
  created new head

  $ echo c1 > c
  $ hg ci -Am C1
  adding c

  $ hg phase --force --secret 1
  $ hg phase --public 1

Rebase and abort without generating new changesets:

  $ hg tglog
  @  4:draft 'C1'
  |
  o  3:draft 'B bis'
  |
  | o  2:secret 'C'
  | |
  | o  1:public 'B'
  |/
  o  0:public 'A'
  
  $ hg rebase -b 4 -d 2
  rebasing 3:a6484957d6b9 "B bis"
  note: rebase of 3:a6484957d6b9 created no changes to commit
  rebasing 4:145842775fec "C1" (tip)
  merging c
  warning: conflicts while merging c! (edit, then use 'hg resolve --mark')
  unresolved conflicts (see hg resolve, then hg rebase --continue)
  [1]

  $ hg tglog
  @  4:draft 'C1'
  |
  o  3:draft 'B bis'
  |
  | @  2:secret 'C'
  | |
  | o  1:public 'B'
  |/
  o  0:public 'A'
  
  $ hg rebase -a
  rebase aborted

  $ hg tglog
  @  4:draft 'C1'
  |
  o  3:draft 'B bis'
  |
  | o  2:secret 'C'
  | |
  | o  1:public 'B'
  |/
  o  0:public 'A'
  

  $ cd ..

rebase abort should not leave working copy in a merge state if tip-1 is public
(issue4082)

  $ hg init abortpublic
  $ cd abortpublic
  $ echo a > a && hg ci -Aqm a
  $ hg book master
  $ hg book foo
  $ echo b > b && hg ci -Aqm b
  $ hg up -q master
  $ echo c > c && hg ci -Aqm c
  $ hg phase -p -r .
  $ hg up -q foo
  $ echo C > c && hg ci -Aqm C
  $ hg log -G --template "{rev} {desc} {bookmarks}"
  @  3 C foo
  |
  | o  2 c master
  | |
  o |  1 b
  |/
  o  0 a
  

  $ hg rebase -d master -r foo
  rebasing 3:6c0f977a22d8 "C" (foo tip)
  merging c
  warning: conflicts while merging c! (edit, then use 'hg resolve --mark')
  unresolved conflicts (see hg resolve, then hg rebase --continue)
  [1]
  $ hg rebase --abort
  rebase aborted
  $ hg log -G --template "{rev} {desc} {bookmarks}"
  @  3 C foo
  |
  | o  2 c master
  | |
  o |  1 b
  |/
  o  0 a
  
  $ cd ..

Make sure we don't clobber changes in the working directory when the
user has somehow managed to update to a different revision (issue4009)

  $ hg init noupdate
  $ cd noupdate
  $ hg book @
  $ echo original > a
  $ hg add a
  $ hg commit -m a
  $ echo x > b
  $ hg add b
  $ hg commit -m b1
  $ hg up 0
  0 files updated, 0 files merged, 1 files removed, 0 files unresolved
  (leaving bookmark @)
  $ hg book foo
  $ echo y > b
  $ hg add b
  $ hg commit -m b2
  created new head

  $ hg rebase -d @ -b foo --tool=internal:fail
  rebasing 2:070cf4580bb5 "b2" (foo tip)
  unresolved conflicts (see hg resolve, then hg rebase --continue)
  [1]

  $ mv .hg/rebasestate ./ # so we're allowed to hg up like in mercurial <2.6.3
  $ hg up -C 0            # user does other stuff in the repo
  0 files updated, 0 files merged, 1 files removed, 0 files unresolved

  $ mv rebasestate .hg/   # user upgrades to 2.7

  $ echo new > a
  $ hg up 1               # user gets an error saying to run hg rebase --abort
  abort: rebase in progress
  (use 'hg rebase --continue' or 'hg rebase --abort')
  [255]

  $ cat a
  new
  $ hg rebase --abort
  rebase aborted
  $ cat a
  new

  $ cd ..

test aborting an interrupted series (issue5084)
  $ hg init interrupted
  $ cd interrupted
  $ touch base
  $ hg add base
  $ hg commit -m base
  $ touch a
  $ hg add a
  $ hg commit -m a
  $ echo 1 > a
  $ hg commit -m 1
  $ touch b
  $ hg add b
  $ hg commit -m b
  $ echo 2 >> a
  $ hg commit -m c
  $ touch d
  $ hg add d
  $ hg commit -m d
  $ hg co -q 1
  $ hg rm a
  $ hg commit -m no-a
  created new head
  $ hg co 0
  0 files updated, 0 files merged, 0 files removed, 0 files unresolved
  $ hg log -G --template "{rev} {desc} {bookmarks}"
  o  6 no-a
  |
  | o  5 d
  | |
  | o  4 c
  | |
  | o  3 b
  | |
  | o  2 1
  |/
  o  1 a
  |
  @  0 base
  
  $ hg --config extensions.n=$TESTDIR/failfilemerge.py rebase -s 3 -d tip
  rebasing 3:3a71550954f1 "b"
  rebasing 4:e80b69427d80 "c"
  abort: ^C
  [255]
  $ hg rebase --abort
  saved backup bundle to $TESTTMP/interrupted/.hg/strip-backup/3d8812cf300d-93041a90-backup.hg
  rebase aborted
  $ hg log -G --template "{rev} {desc} {bookmarks}"
  o  6 no-a
  |
  | o  5 d
  | |
  | o  4 c
  | |
  | o  3 b
  | |
  | o  2 1
  |/
  o  1 a
  |
  @  0 base
  
  $ hg summary
  parent: 0:df4f53cec30a 
   base
  branch: default
  commit: (clean)
  update: 6 new changesets (update)
  phases: 7 draft

  $ cd ..
On the other hand, make sure we *do* clobber changes whenever we
haven't somehow managed to update the repo to a different revision
during a rebase (issue4661)

  $ hg ini yesupdate
  $ cd yesupdate
  $ echo "initial data" > foo.txt
  $ hg add
  adding foo.txt
  $ hg ci -m "initial checkin"
  $ echo "change 1" > foo.txt
  $ hg ci -m "change 1"
  $ hg up 0
  1 files updated, 0 files merged, 0 files removed, 0 files unresolved
  $ echo "conflicting change 1" > foo.txt
  $ hg ci -m "conflicting 1"
  created new head
  $ echo "conflicting change 2" > foo.txt
  $ hg ci -m "conflicting 2"

  $ hg rebase -d 1 --tool 'internal:fail'
  rebasing 2:e4ea5cdc9789 "conflicting 1"
  unresolved conflicts (see hg resolve, then hg rebase --continue)
  [1]
  $ hg rebase --abort
  rebase aborted
  $ hg summary
  parent: 3:b16646383533 tip
   conflicting 2
  branch: default
  commit: (clean)
  update: 1 new changesets, 2 branch heads (merge)
  phases: 4 draft
  $ cd ..

test aborting a rebase succeeds after rebasing with skipped commits onto a
public changeset (issue4896)

  $ hg init succeedonpublic
  $ cd succeedonpublic
  $ echo 'content' > root
  $ hg commit -A -m 'root' -q

set up public branch
  $ echo 'content' > disappear
  $ hg commit -A -m 'disappear public' -q
commit will cause merge conflict on rebase
  $ echo '' > root
  $ hg commit -m 'remove content public' -q
  $ hg phase --public

setup the draft branch that will be rebased onto public commit
  $ hg up -r 0 -q
  $ echo 'content' > disappear
commit will disappear
  $ hg commit -A -m 'disappear draft' -q
  $ echo 'addedcontADDEDentadded' > root
commit will cause merge conflict on rebase
  $ hg commit -m 'add content draft' -q

  $ hg rebase -d 'public()' --tool :merge -q
  note: rebase of 3:0682fd3dabf5 created no changes to commit
  warning: conflicts while merging root! (edit, then use 'hg resolve --mark')
  unresolved conflicts (see hg resolve, then hg rebase --continue)
  [1]
  $ hg rebase --abort
  rebase aborted
  $ cd ..