view tests/test-diff-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

Testing diff --change, --from, --to

  $ hg init a
  $ cd a

  $ echo "first" > file.txt
  $ hg add file.txt
  $ hg commit -m 'first commit' # 0

  $ echo "second" > file.txt
  $ hg commit -m 'second commit' # 1

  $ echo "third" > file.txt
  $ hg commit -m 'third commit' # 2

  $ hg diff --nodates --change 1
  diff -r 4bb65dda5db4 -r e9b286083166 file.txt
  --- a/file.txt
  +++ b/file.txt
  @@ -1,1 +1,1 @@
  -first
  +second

  $ hg diff --change e9b286083166
  diff -r 4bb65dda5db4 -r e9b286083166 file.txt
  --- a/file.txt	Thu Jan 01 00:00:00 1970 +0000
  +++ b/file.txt	Thu Jan 01 00:00:00 1970 +0000
  @@ -1,1 +1,1 @@
  -first
  +second

Test --from and --to

  $ hg diff --from . --rev .
  abort: cannot specify both --from and --rev
  [10]
  $ hg diff --to . --rev .
  abort: cannot specify both --to and --rev
  [10]
  $ hg diff --from . --change .
  abort: cannot specify both --from and --change
  [10]
  $ hg diff --to . --change .
  abort: cannot specify both --to and --change
  [10]
  $ echo dirty > file.txt
  $ hg diff --from .
  diff -r bf5ff72eb7e0 file.txt
  --- a/file.txt	Thu Jan 01 00:00:00 1970 +0000
  +++ b/file.txt	Thu Jan 01 00:00:00 1970 +0000
  @@ -1,1 +1,1 @@
  -third
  +dirty
  $ hg diff --from . --reverse
  diff -r bf5ff72eb7e0 file.txt
  --- a/file.txt	Thu Jan 01 00:00:00 1970 +0000
  +++ b/file.txt	Thu Jan 01 00:00:00 1970 +0000
  @@ -1,1 +1,1 @@
  -dirty
  +third
  $ hg diff --to .
  diff -r bf5ff72eb7e0 file.txt
  --- a/file.txt	Thu Jan 01 00:00:00 1970 +0000
  +++ b/file.txt	Thu Jan 01 00:00:00 1970 +0000
  @@ -1,1 +1,1 @@
  -dirty
  +third
  $ hg diff --from 0 --to 2
  diff -r 4bb65dda5db4 -r bf5ff72eb7e0 file.txt
  --- a/file.txt	Thu Jan 01 00:00:00 1970 +0000
  +++ b/file.txt	Thu Jan 01 00:00:00 1970 +0000
  @@ -1,1 +1,1 @@
  -first
  +third
  $ hg diff --from 2 --to 0
  diff -r bf5ff72eb7e0 -r 4bb65dda5db4 file.txt
  --- a/file.txt	Thu Jan 01 00:00:00 1970 +0000
  +++ b/file.txt	Thu Jan 01 00:00:00 1970 +0000
  @@ -1,1 +1,1 @@
  -third
  +first
  $ hg co -C .
  1 files updated, 0 files merged, 0 files removed, 0 files unresolved

  $ cd ..

Test dumb revspecs: top-level "x:y", "x:", ":y" and ":" ranges should be handled
as pairs even if x == y, but not for "f(x:y)" nor "x::y" (issue3474, issue4774)

  $ hg clone -q a dumbspec
  $ cd dumbspec
  $ echo "wdir" > file.txt

  $ hg diff -r 2:2
  $ hg diff -r 2:.
  $ hg diff -r 2:
  $ hg diff -r :0
  $ hg diff -r '2:first(2:2)'
  $ hg diff -r 'first(2:2)' --nodates
  diff -r bf5ff72eb7e0 file.txt
  --- a/file.txt
  +++ b/file.txt
  @@ -1,1 +1,1 @@
  -third
  +wdir
  $ hg diff -r '(2:2)' --nodates
  diff -r bf5ff72eb7e0 file.txt
  --- a/file.txt
  +++ b/file.txt
  @@ -1,1 +1,1 @@
  -third
  +wdir
  $ hg diff -r 2::2 --nodates
  diff -r bf5ff72eb7e0 file.txt
  --- a/file.txt
  +++ b/file.txt
  @@ -1,1 +1,1 @@
  -third
  +wdir
  $ hg diff -r "2 and 1"
  abort: empty revision range
  [10]

  $ cd ..

  $ hg clone -qr0 a dumbspec-rev0
  $ cd dumbspec-rev0
  $ echo "wdir" > file.txt

  $ hg diff -r :
  $ hg diff -r 'first(:)' --nodates
  diff -r 4bb65dda5db4 file.txt
  --- a/file.txt
  +++ b/file.txt
  @@ -1,1 +1,1 @@
  -first
  +wdir

  $ cd ..

Testing diff --change when merge:

  $ cd a

  $ for i in 1 2 3 4 5 6 7 8 9 10; do
  >    echo $i >> file.txt
  > done
  $ hg commit -m "lots of text" # 3

  $ sed -e 's,^2$,x,' file.txt > file.txt.tmp
  $ mv file.txt.tmp file.txt
  $ hg commit -m "change 2 to x" # 4

  $ hg up -r 3
  1 files updated, 0 files merged, 0 files removed, 0 files unresolved
  $ sed -e 's,^8$,y,' file.txt > file.txt.tmp
  $ mv file.txt.tmp file.txt
  $ hg commit -m "change 8 to y"
  created new head

  $ hg up -C -r 4
  1 files updated, 0 files merged, 0 files removed, 0 files unresolved
  $ hg merge -r 5
  merging file.txt
  0 files updated, 1 files merged, 0 files removed, 0 files unresolved
  (branch merge, don't forget to commit)
  $ hg commit -m "merge 8 to y" # 6

  $ hg diff --change 5
  diff -r ae119d680c82 -r 9085c5c02e52 file.txt
  --- a/file.txt	Thu Jan 01 00:00:00 1970 +0000
  +++ b/file.txt	Thu Jan 01 00:00:00 1970 +0000
  @@ -6,6 +6,6 @@
   5
   6
   7
  -8
  +y
   9
   10

must be similar to 'hg diff --change 5':

  $ hg diff -c 6
  diff -r 273b50f17c6d -r 979ca961fd2e file.txt
  --- a/file.txt	Thu Jan 01 00:00:00 1970 +0000
  +++ b/file.txt	Thu Jan 01 00:00:00 1970 +0000
  @@ -6,6 +6,6 @@
   5
   6
   7
  -8
  +y
   9
   10

merge diff should show only manual edits to a merge:

  $ hg diff --config diff.merge=yes -c 6
(no diff output is expected here)

Construct an "evil merge" that does something other than just the merge.

  $ hg co ".^"
  1 files updated, 0 files merged, 0 files removed, 0 files unresolved
  $ hg merge -r 5
  merging file.txt
  0 files updated, 1 files merged, 0 files removed, 0 files unresolved
  (branch merge, don't forget to commit)
  $ echo 11 >> file.txt
  $ hg ci -m 'merge 8 to y with manual edit of 11' # 7
  created new head
  $ hg diff -c 7
  diff -r 273b50f17c6d -r 8ad85e839ba7 file.txt
  --- a/file.txt	Thu Jan 01 00:00:00 1970 +0000
  +++ b/file.txt	Thu Jan 01 00:00:00 1970 +0000
  @@ -6,6 +6,7 @@
   5
   6
   7
  -8
  +y
   9
   10
  +11
Contrast with the `hg diff -c 7` version above: only the manual edit shows
up, making it easy to identify changes someone is otherwise trying to sneak
into a merge.
  $ hg diff --config diff.merge=yes -c 7
  diff -r 8ad85e839ba7 file.txt
  --- a/file.txt	Thu Jan 01 00:00:00 1970 +0000
  +++ b/file.txt	Thu Jan 01 00:00:00 1970 +0000
  @@ -9,3 +9,4 @@
   y
   9
   10
  +11

Set up a conflict.
  $ hg co ".^"
  1 files updated, 0 files merged, 0 files removed, 0 files unresolved
  $ sed -e 's,^8$,z,' file.txt > file.txt.tmp
  $ mv file.txt.tmp file.txt
  $ hg ci -m 'conflicting edit: 8 to z'
  created new head
  $ echo "this file is new in p1 of the merge" > new-file-p1.txt
  $ hg ci -Am 'new file' new-file-p1.txt
  $ hg log -r . --template 'p1 will be rev {rev}\n'
  p1 will be rev 9
  $ hg co 5
  1 files updated, 0 files merged, 1 files removed, 0 files unresolved
  $ echo "this file is new in p2 of the merge" > new-file-p2.txt
  $ hg ci -Am 'new file' new-file-p2.txt
  created new head
  $ hg log -r . --template 'p2 will be rev {rev}\n'
  p2 will be rev 10
  $ hg co -- 9
  2 files updated, 0 files merged, 1 files removed, 0 files unresolved
  $ hg merge -r 10
  merging file.txt
  warning: conflicts while merging file.txt! (edit, then use 'hg resolve --mark')
  1 files updated, 0 files merged, 0 files removed, 1 files unresolved
  use 'hg resolve' to retry unresolved file merges or 'hg merge --abort' to abandon
  [1]
  $ hg revert file.txt -r .
  $ hg resolve -ma
  (no more unresolved files)
  $ hg commit -m 'merge conflicted edit'
Without diff.merge, it's a diff against p1
  $ hg diff --config diff.merge=no -c 11
  diff -r fd1f17c90d7c -r 5010caab09f6 new-file-p2.txt
  --- /dev/null	Thu Jan 01 00:00:00 1970 +0000
  +++ b/new-file-p2.txt	Thu Jan 01 00:00:00 1970 +0000
  @@ -0,0 +1,1 @@
  +this file is new in p2 of the merge
With diff.merge, it's a diff against the conflicted content.
  $ hg diff --config diff.merge=yes -c 11
  diff -r 5010caab09f6 file.txt
  --- a/file.txt	Thu Jan 01 00:00:00 1970 +0000
  +++ b/file.txt	Thu Jan 01 00:00:00 1970 +0000
  @@ -6,12 +6,6 @@
   5
   6
   7
  -<<<<<<< local: fd1f17c90d7c - test: new file
   z
  -||||||| base:  ae119d680c82 - test: lots of text
  -8
  -=======
  -y
  ->>>>>>> other: d9e7de69eac3 - test: new file
   9
   10

There must _NOT_ be a .hg/merge directory leftover.
  $ test ! -d .hg/merge
(No output is expected)
  $ cd ..