Mercurial > hg
view tests/test-convert-cvsnt-mergepoints.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 | e5e5ee2b60e4 |
children |
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#require cvs no-root $ filterpath() > { > eval "$@" | sed "s:$CVSROOT:*REPO*:g" > } $ cvscall() > { > cvs -f "$@" > } output of 'cvs ci' varies unpredictably, so discard most of it -- just keep the part that matters $ cvsci() > { > cvs -f ci -f "$@" > /dev/null > } $ hgcat() > { > hg --cwd src-hg cat -r tip "$1" > } $ echo "[extensions]" >> $HGRCPATH $ echo "convert = " >> $HGRCPATH create cvs repository $ mkdir cvsmaster $ cd cvsmaster $ CVSROOT=`pwd` $ export CVSROOT $ CVS_OPTIONS=-f $ export CVS_OPTIONS $ cd .. $ rmdir cvsmaster $ filterpath cvscall -Q -d "$CVSROOT" init checkout #1: add foo.txt $ cvscall -Q checkout -d cvsworktmp . $ cd cvsworktmp $ mkdir foo $ cvscall -Q add foo $ cd foo $ echo foo > foo.txt $ cvscall -Q add foo.txt $ cvsci -m "add foo.txt" foo.txt $ cd ../.. $ rm -rf cvsworktmp checkout #2: create MYBRANCH1 and modify foo.txt on it $ cvscall -Q checkout -d cvswork foo $ cd cvswork $ cvscall -q rtag -b -R MYBRANCH1 foo $ cvscall -Q update -P -r MYBRANCH1 $ echo bar > foo.txt $ cvsci -m "bar" foo.txt $ echo baz > foo.txt $ cvsci -m "baz" foo.txt create MYBRANCH1_2 and modify foo.txt some more $ cvscall -q rtag -b -R -r MYBRANCH1 MYBRANCH1_2 foo $ cvscall -Q update -P -r MYBRANCH1_2 $ echo bazzie > foo.txt $ cvsci -m "bazzie" foo.txt create MYBRANCH1_1 and modify foo.txt yet again $ cvscall -q rtag -b -R MYBRANCH1_1 foo $ cvscall -Q update -P -r MYBRANCH1_1 $ echo quux > foo.txt $ cvsci -m "quux" foo.txt merge MYBRANCH1 to MYBRANCH1_1 $ filterpath cvscall -Q update -P -jMYBRANCH1 rcsmerge: warning: conflicts during merge RCS file: *REPO*/foo/foo.txt,v retrieving revision 1.1 retrieving revision 1.1.2.2 Merging differences between 1.1 and 1.1.2.2 into foo.txt carefully placed sleep to dodge cvs bug (optimization?) where it sometimes ignores a "commit" command if it comes too fast (the -f option in cvsci seems to work for all the other commits in this script) $ sleep 1 $ echo xyzzy > foo.txt $ cvsci -m "merge1+clobber" foo.txt #if unix-permissions return to trunk and merge MYBRANCH1_2 $ cvscall -Q update -P -A $ filterpath cvscall -Q update -P -jMYBRANCH1_2 RCS file: *REPO*/foo/foo.txt,v retrieving revision 1.1 retrieving revision 1.1.2.2.2.1 Merging differences between 1.1 and 1.1.2.2.2.1 into foo.txt $ cvsci -m "merge2" foo.txt $ REALCVS=`which cvs` $ echo "for x in \$*; do if [ \"\$x\" = \"rlog\" ]; then echo \"RCS file: $CVSROOT/foo/foo.txt,v\"; cat \"$TESTDIR/test-convert-cvsnt-mergepoints.rlog\"; exit 0; fi; done; $REALCVS \$*" > ../cvs $ chmod +x ../cvs $ PATH=..:${PATH} hg debugcvsps --parents foo collecting CVS rlog 7 log entries creating changesets 7 changeset entries --------------------- PatchSet 1 Date: * (glob) Author: user Branch: HEAD Tag: (none) Branchpoints: MYBRANCH1, MYBRANCH1_1 Log: foo.txt Members: foo.txt:INITIAL->1.1 --------------------- PatchSet 2 Date: * (glob) Author: user Branch: MYBRANCH1 Tag: (none) Parent: 1 Log: bar Members: foo.txt:1.1->1.1.2.1 --------------------- PatchSet 3 Date: * (glob) Author: user Branch: MYBRANCH1 Tag: (none) Branchpoints: MYBRANCH1_2 Parent: 2 Log: baz Members: foo.txt:1.1.2.1->1.1.2.2 --------------------- PatchSet 4 Date: * (glob) Author: user Branch: MYBRANCH1_1 Tag: (none) Parent: 1 Log: quux Members: foo.txt:1.1->1.1.4.1 --------------------- PatchSet 5 Date: * (glob) Author: user Branch: MYBRANCH1_2 Tag: (none) Parent: 3 Log: bazzie Members: foo.txt:1.1.2.2->1.1.2.2.2.1 --------------------- PatchSet 6 Date: * (glob) Author: user Branch: HEAD Tag: (none) Parents: 1,5 Log: merge Members: foo.txt:1.1->1.2 --------------------- PatchSet 7 Date: * (glob) Author: user Branch: MYBRANCH1_1 Tag: (none) Parents: 4,3 Log: merge Members: foo.txt:1.1.4.1->1.1.4.2 #endif $ cd ..