On Mon, Jun 20, 2022 at 04:53:47PM +0800, 欣韩 wrote:

On Mon, Jun 20, 2022 at 3:34 PM Patrick Steinhardt [off-list ref] wrote:

quoted

On Sat, Jun 18, 2022 at 11:01:30AM +0800, Han Xin wrote:

[snip]

quoted

quoted

+test_expect_success 'prepare a repository with a commit-graph contains commit two' '
+     git init source &&
+     echo "$(pwd)/dest.git/objects" >source/.git/objects/info/alternates &&
+     git -C source remote add origin "$(pwd)/dest.git" &&
+     git -C source config remote.origin.promisor true &&
+     git -C source config remote.origin.partialclonefilter blob:none &&
+     # the source repository has the whole refs contains refs/heads/tmp
+     git -C source fetch origin &&
+     (
+             cd source &&
+             test_commit three &&
+             git -c gc.writeCommitGraph=true gc
+     )
+'
+
+test_expect_success 'change the alternates of source to that without commit two' '
+     # now we have a commit-graph in the source repository but without the commit two
+     echo "$(pwd)/alternates/objects" >source/.git/objects/info/alternates
+'
+
+test_expect_success 'fetch the missing commit' '
+     git -C source fetch origin $oid 2>fetch.out &&
+     grep "$oid" fetch.out
+'

This test passes even without your fix, albeit a lot slower compared
to with it. Can we somehow cause it to fail reliably so that the test
becomes effective in catching a regression here?

Could you help me find the reason why this testcase passes even
without the fix.

From the execution of Github Action, it seems that the problem always exist：
https://github.com/chiyutianyi/git/actions/runs/2527421443.

Thanks.
-Han Xin

Hard to say, I'm not sure either. One thing I noticed though is that in
your CI run there's failure in e.g. linux-gcc, but the test run for
linux-musl succeeds. Personally I'm using musl libc on my system, as
well, so maybe it's a discrepancy between musl- and glibc-based systems?

Patrick