view tests/test-histedit-no-change.t @ 49000:dd6b67d5c256 stable

rust: fix unsound `OwningDirstateMap`

As per the previous patch, `OwningDirstateMap` is unsound. Self-referential
structs are difficult to implement correctly in Rust since the compiler is
free to move structs around as much as it wants to. They are also very rarely
needed in practice, so the state-of-the-art on how they should be done within
the Rust rules is still a bit new.

The crate `ouroboros` is an attempt at providing a safe way (in the Rust sense)
of declaring self-referential structs. It is getting a lot attention and was
improved very quickly when soundness issues were found in the past: rather than
relying on our own (limited) review circle, we might as well use the de-facto
common crate to fix this problem. This will give us a much better chance of
finding issues should any new ones be discovered as well as the benefit of
fewer `unsafe` APIs of our own.

I was starting to think about how I would present a safe API to the old struct
but soon realized that the callback-based approach was already done in
`ouroboros`, along with a lot more care towards refusing incorrect structs.

In short: we don't return a mutable reference to the `DirstateMap` anymore, we
expect users of its API to pass a `FnOnce` that takes the map as an argument.
This allows our `OwningDirstateMap` to control the input and output lifetimes
of the code that modifies it to prevent such issues.

Changing to `ouroboros` meant changing every API with it, but it is relatively
low churn in the end. It correctly identified the example buggy modification of
`copy_map_insert` outlined in the previous patch as violating the borrow rules.

Differential Revision: https://phab.mercurial-scm.org/D12429

test for old histedit issue #6:
editing a changeset without any actual change would corrupt the repository

  $ . "$TESTDIR/histedit-helpers.sh"

  $ cat >> $HGRCPATH <<EOF
  > [extensions]
  > histedit=
  > EOF

  $ initrepo ()
  > {
  >     dir="$1"
  >     comment="$2"
  >     if [ -n "${comment}" ]; then
  >         echo % ${comment}
  >         echo % ${comment} | sed 's:.:-:g'
  >     fi
  >     hg init ${dir}
  >     cd ${dir}
  >     for x in a b c d e f ; do
  >         echo $x > $x
  >         hg add $x
  >         hg ci -m $x
  >     done
  >     cd ..
  > }

  $ geneditor ()
  > {
  >     # generate an editor script for selecting changesets to be edited
  >     choice=$1  # changesets that should be edited (using sed line ranges)
  >     cat <<EOF | sed 's:^....::'
  >     # editing the rules, replacing 'pick' with 'edit' for the chosen lines
  >     sed '${choice}s:^pick:edit:' "\$1" > "\${1}.tmp"
  >     mv "\${1}.tmp" "\$1"
  >     # displaying the resulting rules, minus comments and empty lines
  >     sed '/^#/d;/^$/d;s:^:| :' "\$1" >&2
  > EOF
  > }

  $ startediting ()
  > {
  >     # begin an editing session
  >     choice="$1"  # changesets that should be edited
  >     number="$2"  # number of changesets considered (from tip)
  >     comment="$3"
  >     geneditor "${choice}" > edit.sh
  >     echo % start editing the history ${comment}
  >     HGEDITOR="sh ./edit.sh" hg histedit -- -${number} 2>&1 | fixbundle
  > }

  $ continueediting ()
  > {
  >     # continue an edit already in progress
  >     editor="$1"  # message editor when finalizing editing
  >     comment="$2"
  >     echo % finalize changeset editing ${comment}
  >     HGEDITOR=${editor} hg histedit --continue 2>&1 | fixbundle
  > }

  $ graphlog ()
  > {
  >     comment="${1:-log}"
  >     echo % "${comment}"
  >     hg log -G --template '{rev} {node} \"{desc|firstline}\"\n'
  > }


  $ initrepo r1 "test editing with no change"
  % test editing with no change
  -----------------------------
  $ cd r1
  $ graphlog "log before editing"
  % log before editing
  @  5 652413bf663ef2a641cab26574e46d5f5a64a55a "f"
  |
  o  4 e860deea161a2f77de56603b340ebbb4536308ae "e"
  |
  o  3 055a42cdd88768532f9cf79daa407fc8d138de9b "d"
  |
  o  2 177f92b773850b59254aa5e923436f921b55483b "c"
  |
  o  1 d2ae7f538514cd87c17547b0de4cea71fe1af9fb "b"
  |
  o  0 cb9a9f314b8b07ba71012fcdbc544b5a4d82ff5b "a"
  
  $ startediting 2 3 "(not changing anything)" # edit the 2nd of 3 changesets
  % start editing the history (not changing anything)
  | pick 055a42cdd887 3 d
  | edit e860deea161a 4 e
  | pick 652413bf663e 5 f
  0 files updated, 0 files merged, 2 files removed, 0 files unresolved
  Editing (e860deea161a), commit as needed now to split the change
  (to edit e860deea161a, `hg histedit --continue` after making changes)
  $ continueediting true "(leaving commit message unaltered)"
  % finalize changeset editing (leaving commit message unaltered)


check state of working copy
  $ hg id
  794fe033d0a0 tip

  $ graphlog "log after history editing"
  % log after history editing
  @  5 794fe033d0a030f8df77c5de945fca35c9181c30 "f"
  |
  o  4 04d2fab980779f332dec458cc944f28de8b43435 "e"
  |
  o  3 055a42cdd88768532f9cf79daa407fc8d138de9b "d"
  |
  o  2 177f92b773850b59254aa5e923436f921b55483b "c"
  |
  o  1 d2ae7f538514cd87c17547b0de4cea71fe1af9fb "b"
  |
  o  0 cb9a9f314b8b07ba71012fcdbc544b5a4d82ff5b "a"
  

  $ cd ..

  $ initrepo r2 "test editing with no change, then abort"
  % test editing with no change, then abort
  -----------------------------------------
  $ cd r2
  $ graphlog "log before editing"
  % log before editing
  @  5 652413bf663ef2a641cab26574e46d5f5a64a55a "f"
  |
  o  4 e860deea161a2f77de56603b340ebbb4536308ae "e"
  |
  o  3 055a42cdd88768532f9cf79daa407fc8d138de9b "d"
  |
  o  2 177f92b773850b59254aa5e923436f921b55483b "c"
  |
  o  1 d2ae7f538514cd87c17547b0de4cea71fe1af9fb "b"
  |
  o  0 cb9a9f314b8b07ba71012fcdbc544b5a4d82ff5b "a"
  
  $ startediting 1,2 3 "(not changing anything)" # edit the 1st two of 3 changesets
  % start editing the history (not changing anything)
  | edit 055a42cdd887 3 d
  | edit e860deea161a 4 e
  | pick 652413bf663e 5 f
  0 files updated, 0 files merged, 3 files removed, 0 files unresolved
  Editing (055a42cdd887), commit as needed now to split the change
  (to edit 055a42cdd887, `hg histedit --continue` after making changes)
  $ continueediting true "(leaving commit message unaltered)"
  % finalize changeset editing (leaving commit message unaltered)
  Editing (e860deea161a), commit as needed now to split the change
  (to edit e860deea161a, `hg histedit --continue` after making changes)
  $ graphlog "log after first edit"
  % log after first edit
  @  6 e5ae3ca2f1ffdbd89ec41ebc273a231f7c3022f2 "d"
  |
  | o  5 652413bf663ef2a641cab26574e46d5f5a64a55a "f"
  | |
  | o  4 e860deea161a2f77de56603b340ebbb4536308ae "e"
  | |
  | o  3 055a42cdd88768532f9cf79daa407fc8d138de9b "d"
  |/
  o  2 177f92b773850b59254aa5e923436f921b55483b "c"
  |
  o  1 d2ae7f538514cd87c17547b0de4cea71fe1af9fb "b"
  |
  o  0 cb9a9f314b8b07ba71012fcdbc544b5a4d82ff5b "a"
  

abort editing session, after first forcibly updating away
  $ hg up 0
  abort: histedit in progress
  (use 'hg histedit --continue' or 'hg histedit --abort')
  [20]
  $ mv .hg/histedit-state .hg/histedit-state-ignore
  $ hg up 0
  0 files updated, 0 files merged, 3 files removed, 0 files unresolved
  $ mv .hg/histedit-state-ignore .hg/histedit-state
  $ hg sum
  parent: 0:cb9a9f314b8b 
   a
  branch: default
  commit: 1 added, 1 unknown (new branch head)
  update: 6 new changesets (update)
  phases: 7 draft
  hist:   2 remaining (histedit --continue)

  $ hg histedit --abort 2>&1 | fixbundle

modified files should survive the abort when we've moved away already
  $ hg st
  A e
  ? edit.sh

  $ graphlog "log after abort"
  % log after abort
  o  5 652413bf663ef2a641cab26574e46d5f5a64a55a "f"
  |
  o  4 e860deea161a2f77de56603b340ebbb4536308ae "e"
  |
  o  3 055a42cdd88768532f9cf79daa407fc8d138de9b "d"
  |
  o  2 177f92b773850b59254aa5e923436f921b55483b "c"
  |
  o  1 d2ae7f538514cd87c17547b0de4cea71fe1af9fb "b"
  |
  @  0 cb9a9f314b8b07ba71012fcdbc544b5a4d82ff5b "a"
  
aborting and not changing files can skip mentioning updating (no) files
  $ hg up
  5 files updated, 0 files merged, 0 files removed, 0 files unresolved
  $ hg commit --close-branch -m 'closebranch'
  $ startediting 1 1 "(not changing anything)" # edit the 3rd of 3 changesets
  % start editing the history (not changing anything)
  | edit 292aec348d9e 6 closebranch
  Editing (292aec348d9e), commit as needed now to split the change
  (to edit 292aec348d9e, `hg histedit --continue` after making changes)
  $ hg histedit --abort

  $ cd ..