rust: Add type annotation to fix inference on Rust Nightly
When compiling with Rust Nightly, the im-rs crate silently makes use of the
experimental language feature for trait impl specialization. This apperently
changes public its APIs in subtle ways such that type inference of some user
code can fail where it succeeds when specialization is disabled.
This made Mercurial’s Rust unit tests have compilation errors on Nightly.
I have not managed to find the exactl root cause, but I wrote down my findings
so far at https://github.com/bodil/im-rs/issues/188
This adds type annotation to make unit tests rely less on type inference
and work around the issue.
Differential Revision: https://phab.mercurial-scm.org/D10742
#testcases skip-detection fail-if-detected
Test situations that "should" only be reproducible:
- on networked filesystems, or
- user using `hg debuglocks` to eliminate the lock file, or
- something (that doesn't respect the lock file) writing to the .hg directory
while we're running
$ hg init a
$ cd a
$ cat > "$TESTTMP/waitlock_editor.sh" <<EOF
> [ -n "\${WAITLOCK_ANNOUNCE:-}" ] && touch "\${WAITLOCK_ANNOUNCE}"
> f="\${WAITLOCK_FILE}"
> start=\`date +%s\`
> timeout=5
> while [ \\( ! -f \$f \\) -a \\( ! -L \$f \\) ]; do
> now=\`date +%s\`
> if [ "\`expr \$now - \$start\`" -gt \$timeout ]; then
> echo "timeout: \$f was not created in \$timeout seconds (it is now \$(date +%s))"
> exit 1
> fi
> sleep 0.1
> done
> if [ \$# -gt 1 ]; then
> cat "\$@"
> fi
> EOF
Things behave differently if we don't already have a 00changelog.i file when
this all starts, so let's make one.
$ echo r0 > r0
$ hg commit -qAm 'r0'
Start an hg commit that will take a while
$ EDITOR_STARTED="$(pwd)/.editor_started"
$ MISCHIEF_MANAGED="$(pwd)/.mischief_managed"
$ JOBS_FINISHED="$(pwd)/.jobs_finished"
#if fail-if-detected
$ cat >> .hg/hgrc << EOF
> [debug]
> revlog.verifyposition.changelog = fail
> EOF
#endif
$ echo foo > foo
$ (WAITLOCK_ANNOUNCE="${EDITOR_STARTED}" \
> WAITLOCK_FILE="${MISCHIEF_MANAGED}" \
> HGEDITOR="sh $TESTTMP/waitlock_editor.sh" \
> hg commit -qAm 'r1 (foo)' --edit foo > .foo_commit_out 2>&1 ; touch "${JOBS_FINISHED}") &
Wait for the "editor" to actually start
$ WAITLOCK_FILE="${EDITOR_STARTED}" sh "$TESTTMP/waitlock_editor.sh"
Break the locks, and make another commit.
$ hg debuglocks -LW
$ echo bar > bar
$ hg commit -qAm 'r2 (bar)' bar
$ hg debugrevlogindex -c
rev linkrev nodeid p1 p2
0 0 222799e2f90b 000000000000 000000000000
1 1 6f124f6007a0 222799e2f90b 000000000000
Awaken the editor from that first commit
$ touch "${MISCHIEF_MANAGED}"
And wait for it to finish
$ WAITLOCK_FILE="${JOBS_FINISHED}" sh "$TESTTMP/waitlock_editor.sh"
#if skip-detection
(Ensure there was no output)
$ cat .foo_commit_out
And observe a corrupted repository -- rev 2's linkrev is 1, which should never
happen for the changelog (the linkrev should always refer to itself).
$ hg debugrevlogindex -c
rev linkrev nodeid p1 p2
0 0 222799e2f90b 000000000000 000000000000
1 1 6f124f6007a0 222799e2f90b 000000000000
2 1 ac80e6205bb2 222799e2f90b 000000000000
#endif
#if fail-if-detected
$ cat .foo_commit_out
transaction abort!
rollback completed
note: commit message saved in .hg/last-message.txt
note: use 'hg commit --logfile .hg/last-message.txt --edit' to reuse it
abort: 00changelog.i: file cursor at position 249, expected 121
And no corruption in the changelog.
$ hg debugrevlogindex -c
rev linkrev nodeid p1 p2
0 0 222799e2f90b 000000000000 000000000000
1 1 6f124f6007a0 222799e2f90b 000000000000 (missing-correct-output !)
And, because of transactions, there's none in the manifestlog either.
$ hg debugrevlogindex -m
rev linkrev nodeid p1 p2
0 0 7b7020262a56 000000000000 000000000000
1 1 ad3fe36d86d9 7b7020262a56 000000000000
#endif