Mercurial > hg
view tests/test-absorb-rename.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
author | Raphaël Gomès <rgomes@octobus.net> |
---|---|
date | Tue, 05 Apr 2022 10:55:28 +0200 |
parents | 31dfa7dac4c9 |
children |
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$ cat >> $HGRCPATH << EOF > [diff] > git=1 > [extensions] > absorb= > EOF $ sedi() { # workaround check-code > pattern="$1" > shift > for i in "$@"; do > sed "$pattern" "$i" > "$i".tmp > mv "$i".tmp "$i" > done > } rename a to b, then b to a $ hg init repo1 $ cd repo1 $ echo 1 > a $ hg ci -A a -m 1 $ hg mv a b $ echo 2 >> b $ hg ci -m 2 $ hg mv b a $ echo 3 >> a $ hg ci -m 3 $ hg annotate -ncf a 0 eff892de26ec a: 1 1 bf56e1f4f857 b: 2 2 0b888b00216c a: 3 $ sedi 's/$/a/' a $ hg absorb -apq showing changes for a @@ -0,3 +0,3 @@ eff892d -1 bf56e1f -2 0b888b0 -3 eff892d +1a bf56e1f +2a 0b888b0 +3a 3 changesets affected 0b888b0 3 bf56e1f 2 eff892d 1 $ hg status $ hg annotate -ncf a 0 5d1c5620e6f2 a: 1a 1 9a14ffe67ae9 b: 2a 2 9191d121a268 a: 3a when the first changeset is public $ hg phase --public -r 0 $ sedi 's/a/A/' a $ hg absorb -apq showing changes for a @@ -0,3 +0,3 @@ -1a 9a14ffe -2a 9191d12 -3a +1A 9a14ffe +2A 9191d12 +3A 2 changesets affected 9191d12 3 9a14ffe 2 $ hg diff diff --git a/a b/a --- a/a +++ b/a @@ -1,3 +1,3 @@ -1a +1A 2A 3A copy a to b $ cd .. $ hg init repo2 $ cd repo2 $ echo 1 > a $ hg ci -A a -m 1 $ hg cp a b $ echo 2 >> b $ hg ci -m 2 $ hg log -T '{rev}:{node|short} {desc}\n' 1:17b72129ab68 2 0:eff892de26ec 1 $ sedi 's/$/a/' a $ sedi 's/$/b/' b $ hg absorb -apq showing changes for a @@ -0,1 +0,1 @@ eff892d -1 eff892d +1a showing changes for b @@ -0,2 +0,2 @@ -1 17b7212 -2 +1b 17b7212 +2b 2 changesets affected 17b7212 2 eff892d 1 $ hg diff diff --git a/b b/b --- a/b +++ b/b @@ -1,2 +1,2 @@ -1 +1b 2b copy b to a $ cd .. $ hg init repo3 $ cd repo3 $ echo 1 > b $ hg ci -A b -m 1 $ hg cp b a $ echo 2 >> a $ hg ci -m 2 $ hg log -T '{rev}:{node|short} {desc}\n' 1:e62c256d8b24 2 0:55105f940d5c 1 $ sedi 's/$/a/' a $ sedi 's/$/a/' b $ hg absorb -apq showing changes for a @@ -0,2 +0,2 @@ -1 e62c256 -2 +1a e62c256 +2a showing changes for b @@ -0,1 +0,1 @@ 55105f9 -1 55105f9 +1a 2 changesets affected e62c256 2 55105f9 1 $ hg diff diff --git a/a b/a --- a/a +++ b/a @@ -1,2 +1,2 @@ -1 +1a 2a "move" b to both a and c, follow a - sorted alphabetically $ cd .. $ hg init repo4 $ cd repo4 $ echo 1 > b $ hg ci -A b -m 1 $ hg cp b a $ hg cp b c $ hg rm b $ echo 2 >> a $ echo 3 >> c $ hg commit -m cp $ hg log -T '{rev}:{node|short} {desc}\n' 1:366daad8e679 cp 0:55105f940d5c 1 $ sedi 's/$/a/' a $ sedi 's/$/c/' c $ hg absorb -apq showing changes for a @@ -0,2 +0,2 @@ 55105f9 -1 366daad -2 55105f9 +1a 366daad +2a showing changes for c @@ -0,2 +0,2 @@ -1 366daad -3 +1c 366daad +3c 2 changesets affected 366daad cp 55105f9 1 $ hg log -G -p -T '{rev}:{node|short} {desc}\n' @ 1:70606019f91b cp | diff --git a/b b/a | rename from b | rename to a | --- a/b | +++ b/a | @@ -1,1 +1,2 @@ | 1a | +2a | diff --git a/b b/c | copy from b | copy to c | --- a/b | +++ b/c | @@ -1,1 +1,2 @@ | -1a | +1 | +3c | o 0:bfb67c3539c1 1 diff --git a/b b/b new file mode 100644 --- /dev/null +++ b/b @@ -0,0 +1,1 @@ +1a run absorb again would apply the change to c $ hg absorb -apq showing changes for c @@ -0,1 +0,1 @@ 7060601 -1 7060601 +1c 1 changesets affected 7060601 cp $ hg log -G -p -T '{rev}:{node|short} {desc}\n' @ 1:8bd536cce368 cp | diff --git a/b b/a | rename from b | rename to a | --- a/b | +++ b/a | @@ -1,1 +1,2 @@ | 1a | +2a | diff --git a/b b/c | copy from b | copy to c | --- a/b | +++ b/c | @@ -1,1 +1,2 @@ | -1a | +1c | +3c | o 0:bfb67c3539c1 1 diff --git a/b b/b new file mode 100644 --- /dev/null +++ b/b @@ -0,0 +1,1 @@ +1a "move" b to a, c and d, follow d if a gets renamed to e, and c is deleted $ cd .. $ hg init repo5 $ cd repo5 $ echo 1 > b $ hg ci -A b -m 1 $ hg cp b a $ hg cp b c $ hg cp b d $ hg rm b $ echo 2 >> a $ echo 3 >> c $ echo 4 >> d $ hg commit -m cp $ hg mv a e $ hg rm c $ hg commit -m mv $ hg log -T '{rev}:{node|short} {desc}\n' 2:49911557c471 mv 1:7bc3d43ede83 cp 0:55105f940d5c 1 $ sedi 's/$/e/' e $ sedi 's/$/d/' d $ hg absorb -apq showing changes for d @@ -0,2 +0,2 @@ 55105f9 -1 7bc3d43 -4 55105f9 +1d 7bc3d43 +4d showing changes for e @@ -0,2 +0,2 @@ -1 7bc3d43 -2 +1e 7bc3d43 +2e 2 changesets affected 7bc3d43 cp 55105f9 1 $ hg diff diff --git a/e b/e --- a/e +++ b/e @@ -1,2 +1,2 @@ -1 +1e 2e $ hg log -G -p -T '{rev}:{node|short} {desc}\n' @ 2:34be9b0c786e mv | diff --git a/c b/c | deleted file mode 100644 | --- a/c | +++ /dev/null | @@ -1,2 +0,0 @@ | -1 | -3 | diff --git a/a b/e | rename from a | rename to e | o 1:13e56db5948d cp | diff --git a/b b/a | rename from b | rename to a | --- a/b | +++ b/a | @@ -1,1 +1,2 @@ | -1d | +1 | +2e | diff --git a/b b/c | copy from b | copy to c | --- a/b | +++ b/c | @@ -1,1 +1,2 @@ | -1d | +1 | +3 | diff --git a/b b/d | copy from b | copy to d | --- a/b | +++ b/d | @@ -1,1 +1,2 @@ | 1d | +4d | o 0:0037613a5dc6 1 diff --git a/b b/b new file mode 100644 --- /dev/null +++ b/b @@ -0,0 +1,1 @@ +1d