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view tests/test-convert-cvs-detectmerge.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 Test config convert.cvsps.mergefrom config setting. (Should test similar mergeto feature, but I don't understand it yet.) Requires builtin cvsps. $ CVSROOT=`pwd`/cvsrepo $ export CVSROOT $ cvscall() > { > cvs -f "$@" > } output of 'cvs ci' varies unpredictably, so just discard it XXX copied from test-convert-cvs-synthetic $ cvsci() > { > sleep 1 > cvs -f ci "$@" > /dev/null > } XXX copied from test-convert-cvs-synthetic $ cat <<EOF >> $HGRCPATH > [extensions] > convert = > [convert] > cvsps.cache = 0 > cvsps.mergefrom = \[MERGE from (\S+)\] > EOF create cvs repository with one project $ cvscall -q -d "$CVSROOT" init $ mkdir cvsrepo/proj populate cvs repository $ cvscall -Q co proj $ cd proj $ touch file1 $ cvscall -Q add file1 $ cvsci -m"add file1 on trunk" cvs commit: Examining . create two release branches $ cvscall -q tag -b v1_0 T file1 $ cvscall -q tag -b v1_1 T file1 modify file1 on branch v1_0 $ cvscall -Q update -rv1_0 $ sleep 1 $ echo "change" >> file1 $ cvsci -m"add text" cvs commit: Examining . make unrelated change on v1_1 $ cvscall -Q update -rv1_1 $ touch unrelated $ cvscall -Q add unrelated $ cvsci -m"unrelated change" cvs commit: Examining . merge file1 to v1_1 $ cvscall -Q update -jv1_0 RCS file: $TESTTMP/cvsrepo/proj/file1,v retrieving revision 1.1 retrieving revision 1.1.2.1 Merging differences between 1.1 and 1.1.2.1 into file1 $ cvsci -m"add text [MERGE from v1_0]" cvs commit: Examining . merge change to trunk $ cvscall -Q update -A $ cvscall -Q update -jv1_1 RCS file: $TESTTMP/cvsrepo/proj/file1,v retrieving revision 1.1 retrieving revision 1.1.4.1 Merging differences between 1.1 and 1.1.4.1 into file1 $ cvsci -m"add text [MERGE from v1_1]" cvs commit: Examining . non-merged change on trunk $ echo "foo" > file2 $ cvscall -Q add file2 $ cvsci -m"add file2 on trunk" file2 this will create rev 1.3 change on trunk to backport $ echo "backport me" >> file1 $ cvsci -m"add other text" file1 $ cvscall log file1 RCS file: $TESTTMP/cvsrepo/proj/file1,v Working file: file1 head: 1.3 branch: locks: strict access list: symbolic names: v1_1: 1.1.0.4 v1_0: 1.1.0.2 keyword substitution: kv total revisions: 5; selected revisions: 5 description: ---------------------------- revision 1.3 date: * (glob) add other text ---------------------------- revision 1.2 date: * (glob) add text [MERGE from v1_1] ---------------------------- revision 1.1 date: * (glob) branches: 1.1.2; 1.1.4; add file1 on trunk ---------------------------- revision 1.1.4.1 date: * (glob) add text [MERGE from v1_0] ---------------------------- revision 1.1.2.1 date: * (glob) add text ============================================================================= XXX how many ways are there to spell "trunk" with CVS? backport trunk change to v1_1 $ cvscall -Q update -rv1_1 $ cvscall -Q update -j1.2 -j1.3 file1 RCS file: $TESTTMP/cvsrepo/proj/file1,v retrieving revision 1.2 retrieving revision 1.3 Merging differences between 1.2 and 1.3 into file1 $ cvsci -m"add other text [MERGE from HEAD]" file1 fix bug on v1_1, merge to trunk with error $ cvscall -Q update -rv1_1 $ echo "merge forward" >> file1 $ cvscall -Q tag unmerged $ cvsci -m"fix file1" cvs commit: Examining . $ cvscall -Q update -A $ cvscall -Q update -junmerged -jv1_1 RCS file: $TESTTMP/cvsrepo/proj/file1,v retrieving revision 1.1.4.2 retrieving revision 1.1.4.3 Merging differences between 1.1.4.2 and 1.1.4.3 into file1 note the typo in the commit log message $ cvsci -m"fix file1 [MERGE from v1-1]" cvs commit: Examining . $ cvs -Q tag -d unmerged convert to hg $ cd .. $ hg convert proj proj.hg initializing destination proj.hg repository connecting to $TESTTMP/cvsrepo scanning source... collecting CVS rlog 12 log entries creating changesets warning: CVS commit message references non-existent branch 'v1-1': fix file1 [MERGE from v1-1] 10 changeset entries sorting... converting... 9 add file1 on trunk 8 unrelated change 7 add text 6 add text [MERGE from v1_0] 5 add text [MERGE from v1_1] 4 add file2 on trunk 3 add other text 2 add other text [MERGE from HEAD] 1 fix file1 0 fix file1 [MERGE from v1-1] complete log $ template="{rev}: '{branches}' {desc}\n" $ hg -R proj.hg log --template="$template" 9: '' fix file1 [MERGE from v1-1] 8: 'v1_1' fix file1 7: 'v1_1' add other text [MERGE from HEAD] 6: '' add other text 5: '' add file2 on trunk 4: '' add text [MERGE from v1_1] 3: 'v1_1' add text [MERGE from v1_0] 2: 'v1_0' add text 1: 'v1_1' unrelated change 0: '' add file1 on trunk graphical log $ hg -R proj.hg log -G --template="$template" o 9: '' fix file1 [MERGE from v1-1] | | o 8: 'v1_1' fix file1 | | | o 7: 'v1_1' add other text [MERGE from HEAD] |/| o | 6: '' add other text | | o | 5: '' add file2 on trunk | | o | 4: '' add text [MERGE from v1_1] |\| | o 3: 'v1_1' add text [MERGE from v1_0] | |\ +---o 2: 'v1_0' add text | | | o 1: 'v1_1' unrelated change |/ o 0: '' add file1 on trunk