view tests/test-rebase-base-flag.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 the "--base" flag of the rebase command. (Tests unrelated to the "--base"
flag should probably live in somewhere else)

  $ cat >> $HGRCPATH <<EOF
  > [extensions]
  > rebase=
  > drawdag=$TESTDIR/drawdag.py
  > 
  > [phases]
  > publish=False
  > 
  > [alias]
  > tglog = log -G --template "{rev}: {node|short} {desc}"
  > EOF

  $ rebasewithdag() {
  >   N=`"$PYTHON" -c "print($N+1)"`
  >   hg init repo$N && cd repo$N
  >   hg debugdrawdag
  >   hg rebase "$@" > _rebasetmp
  >   r=$?
  >   grep -v 'saved backup bundle' _rebasetmp
  >   [ $r -eq 0 ] && hg tglog
  >   cd ..
  >   return $r
  > }

Single branching point, without merge:

  $ rebasewithdag -b D -d Z <<'EOS'
  >     D E
  >     |/
  > Z B C   # C: branching point, E should be picked
  >  \|/    # B should not be picked
  >   A
  >   |
  >   R
  > EOS
  rebasing 3:d6003a550c2c C "C"
  rebasing 5:4526cf523425 D "D"
  rebasing 6:b296604d9846 E tip "E"
  o  6: 4870f5e7df37 E
  |
  | o  5: dc999528138a D
  |/
  o  4: 6b3e11729672 C
  |
  o  3: 57e70bad1ea3 Z
  |
  | o  2: c1e6b162678d B
  |/
  o  1: 21a6c4502885 A
  |
  o  0: b41ce7760717 R
  
Multiple branching points caused by selecting a single merge changeset:

  $ rebasewithdag -b E -d Z <<'EOS'
  >     E
  >    /|
  >   B C D  # B, C: multiple branching points
  >   | |/   # D should not be picked
  > Z | /
  >  \|/
  >   A
  >   |
  >   R
  > EOS
  rebasing 2:c1e6b162678d B "B"
  rebasing 3:d6003a550c2c C "C"
  rebasing 6:54c8f00cb91c E tip "E"
  o    6: 00598421b616 E
  |\
  | o  5: 6b3e11729672 C
  | |
  o |  4: 85260910e847 B
  |/
  o  3: 57e70bad1ea3 Z
  |
  | o  2: 8924700906fe D
  |/
  o  1: 21a6c4502885 A
  |
  o  0: b41ce7760717 R
  
Rebase should not extend the "--base" revset using "descendants":

  $ rebasewithdag -b B -d Z <<'EOS'
  >     E
  >    /|
  > Z B C  # descendants(B) = B+E. With E, C will be included incorrectly
  >  \|/
  >   A
  >   |
  >   R
  > EOS
  rebasing 2:c1e6b162678d B "B"
  rebasing 5:54c8f00cb91c E tip "E"
  o    5: e583bf3ff54c E
  |\
  | o  4: 85260910e847 B
  | |
  | o  3: 57e70bad1ea3 Z
  | |
  o |  2: d6003a550c2c C
  |/
  o  1: 21a6c4502885 A
  |
  o  0: b41ce7760717 R
  
Rebase should not simplify the "--base" revset using "roots":

  $ rebasewithdag -b B+E -d Z <<'EOS'
  >     E
  >    /|
  > Z B C  # roots(B+E) = B. Without E, C will be missed incorrectly
  >  \|/
  >   A
  >   |
  >   R
  > EOS
  rebasing 2:c1e6b162678d B "B"
  rebasing 3:d6003a550c2c C "C"
  rebasing 5:54c8f00cb91c E tip "E"
  o    5: 00598421b616 E
  |\
  | o  4: 6b3e11729672 C
  | |
  o |  3: 85260910e847 B
  |/
  o  2: 57e70bad1ea3 Z
  |
  o  1: 21a6c4502885 A
  |
  o  0: b41ce7760717 R
  
The destination is one of the two branching points of a merge:

  $ rebasewithdag -b F -d Z <<'EOS'
  >     F
  >    / \
  >   E   D
  >  /   /
  > Z   C
  >  \ /
  >   B
  >   |
  >   A
  > EOS
  nothing to rebase
  [1]

Multiple branching points caused by multiple bases (issue5420):

  $ rebasewithdag -b E1+E2+C2+B1 -d Z <<'EOS'
  >   Z    E2
  >   |   /
  >   F E1 C2
  >   |/  /
  >   E C1 B2
  >   |/  /
  >   C B1
  >   |/
  >   B
  >   |
  >   A
  >   |
  >   R
  > EOS
  rebasing 3:a113dbaa660a B1 "B1"
  rebasing 5:06ce7b1cc8c2 B2 "B2"
  rebasing 6:0ac98cce32d3 C1 "C1"
  rebasing 8:781512f5e33d C2 "C2"
  rebasing 9:428d8c18f641 E1 "E1"
  rebasing 11:e1bf82f6b6df E2 "E2"
  o  12: e4a37b6fdbd2 E2
  |
  o  11: 9675bea983df E1
  |
  | o  10: 4faf5d4c80dc C2
  | |
  | o  9: d4799b1ad57d C1
  |/
  | o  8: 772732dc64d6 B2
  | |
  | o  7: ad3ac528a49f B1
  |/
  o  6: 2cbdfca6b9d5 Z
  |
  o  5: fcdb3293ec13 F
  |
  o  4: a4652bb8ac54 E
  |
  o  3: bd5548558fcf C
  |
  o  2: c1e6b162678d B
  |
  o  1: 21a6c4502885 A
  |
  o  0: b41ce7760717 R
  
Multiple branching points with multiple merges:

  $ rebasewithdag -b G+P -d Z <<'EOS'
  > G   H   P
  > |\ /|   |\
  > F E D   M N
  >  \|/|  /| |\
  > Z C B I J K L
  >  \|/  |/  |/
  >   A   A   A
  > EOS
  rebasing 2:dc0947a82db8 C "C"
  rebasing 8:4e4f9194f9f1 D "D"
  rebasing 9:03ca77807e91 E "E"
  rebasing 10:afc707c82df0 F "F"
  rebasing 13:690dfff91e9e G "G"
  rebasing 14:2893b886bb10 H "H"
  rebasing 3:08ebfeb61bac I "I"
  rebasing 4:a0a5005cec67 J "J"
  rebasing 5:83780307a7e8 K "K"
  rebasing 6:e131637a1cb6 L "L"
  rebasing 11:d1f6d0c3c7e4 M "M"
  rebasing 12:7aaec6f81888 N "N"
  rebasing 15:325bc8f1760d P tip "P"
  o    15: 6ef6a0ea3b18 P
  |\
  | o    14: 20ba3610a7e5 N
  | |\
  o \ \    13: cd4f6c06d2ab M
  |\ \ \
  | | | o  12: bca872041455 L
  | | | |
  | | o |  11: 7bbb6c8a6ad7 K
  | | |/
  | o /  10: de0cbffe893e J
  | |/
  o /  9: 0e710f176a88 I
  |/
  | o    8: 52507bab39ca H
  | |\
  | | | o  7: bb5fe4652f0d G
  | | |/|
  | | | o  6: f4ad4b31daf4 F
  | | | |
  | | o |  5: b168f85f2e78 E
  | | |/
  | o |  4: 8d09fcdb5594 D
  | |\|
  +---o  3: ab70b4c5a9c9 C
  | |
  o |  2: 262e37e34f63 Z
  | |
  | o  1: 112478962961 B
  |/
  o  0: 426bada5c675 A
  
Slightly more complex merge case (mentioned in https://www.mercurial-scm.org/pipermail/mercurial-devel/2016-November/091074.html):

  $ rebasewithdag -b A3+B3 -d Z <<'EOF'
  > Z     C1    A3     B3
  > |    /     / \    / \
  > M3 C0     A1  A2 B1  B2
  > | /       |   |  |   |
  > M2        M1  C1 C1  M3
  > |
  > M1
  > |
  > M0
  > EOF
  rebasing 4:8817fae53c94 C0 "C0"
  rebasing 6:06ca5dfe3b5b B2 "B2"
  rebasing 7:73508237b032 C1 "C1"
  rebasing 9:fdb955e2faed A2 "A2"
  rebasing 11:4e449bd1a643 A3 "A3"
  rebasing 10:0a33b0519128 B1 "B1"
  rebasing 12:209327807c3a B3 tip "B3"
  o    12: ceb984566332 B3
  |\
  | o  11: 19d93caac497 B1
  | |
  | | o    10: 058e73d3916b A3
  | | |\
  | +---o  9: 0ba13ad72234 A2
  | | |
  | o |  8: c122c2af10c6 C1
  | | |
  o | |  7: 74275896650e B2
  | | |
  | o |  6: 455ba9bd3ea2 C0
  |/ /
  o |  5: b3d7d2fda53b Z
  | |
  o |  4: 182ab6383dd7 M3
  | |
  o |  3: 6c3f73563d5f M2
  | |
  | o  2: 88c860fffcc2 A1
  |/
  o  1: bc852baa85dd M1
  |
  o  0: dbdfc5c9bcd5 M0
  
Disconnected graph:

  $ rebasewithdag -b B -d Z <<'EOS'
  >   B
  >   |
  > Z A
  > EOS
  nothing to rebase from 112478962961 to 48b9aae0607f
  [1]

Multiple roots. Roots are ancestors of dest:

  $ rebasewithdag -b B+D -d Z <<'EOF'
  > D Z B
  >  \|\|
  >   C A
  > EOF
  rebasing 2:112478962961 B "B"
  rebasing 3:b70f76719894 D "D"
  o  4: 511efad7bf13 D
  |
  | o  3: 25c4e279af62 B
  |/
  o    2: 3a49f54d7bb1 Z
  |\
  | o  1: 96cc3511f894 C
  |
  o  0: 426bada5c675 A
  
Multiple roots. One root is not an ancestor of dest:

  $ rebasewithdag -b B+D -d Z <<'EOF'
  > Z B D
  >  \|\|
  >   A C
  > EOF
  nothing to rebase from f675d5a1c6a4+b70f76719894 to 262e37e34f63
  [1]

Multiple roots. One root is not an ancestor of dest. Select using a merge:

  $ rebasewithdag -b E -d Z <<'EOF'
  >   E
  >   |\
  > Z B D
  >  \|\|
  >   A C
  > EOF
  rebasing 2:f675d5a1c6a4 B "B"
  rebasing 5:f68696fe6af8 E tip "E"
  o    5: f6e6f5081554 E
  |\
  | o    4: 30cabcba27be B
  | |\
  | | o  3: 262e37e34f63 Z
  | | |
  o | |  2: b70f76719894 D
  |/ /
  o /  1: 96cc3511f894 C
   /
  o  0: 426bada5c675 A
  
Multiple roots. Two children share two parents while dest has only one parent:

  $ rebasewithdag -b B+D -d Z <<'EOF'
  > Z B D
  >  \|\|\
  >   A C A
  > EOF
  rebasing 2:f675d5a1c6a4 B "B"
  rebasing 3:c2a779e13b56 D "D"
  o    4: 5eecd056b5f8 D
  |\
  +---o  3: 30cabcba27be B
  | |/
  | o  2: 262e37e34f63 Z
  | |
  o |  1: 96cc3511f894 C
   /
  o  0: 426bada5c675 A