patch: support diff data loss detection and upgrade
In worst case, generating diff in upgrade mode can be two times more expensive
than generating it in git mode directly: we may have to regenerate the whole
diff again whenever a git feature is detected. Also, the first diff attempt is
completely buffered instead of being streamed. That said, even without having
profiled it yet, I am convinced we can fast-path the upgrade mode if necessary
were it to be used in regular diff commands, and not only in mq where avoiding
data loss is worth the price.
#!/bin/sh
# http://mercurial.selenic.com/bts/issue660
hg init a
cd a
echo a > a
mkdir b
echo b > b/b
hg commit -A -m "a is file, b is dir"
echo % file replaced with directory
rm a
mkdir a
echo a > a/a
echo % should fail - would corrupt dirstate
hg add a/a
echo % removing shadow
hg rm --after a
echo % should succeed - shadow removed
hg add a/a
echo % directory replaced with file
rm -r b
echo b > b
echo % should fail - would corrupt dirstate
hg add b
echo % removing shadow
hg rm --after b/b
echo % should succeed - shadow removed
hg add b
echo % look what we got
hg st
echo % revert reintroducing shadow - should fail
rm -r a b
hg revert b/b
echo % revert all - should succeed
hg revert --all
hg st
echo % addremove
rm -r a b
mkdir a
echo a > a/a
echo b > b
hg addremove
hg st
echo % commit
hg ci -A -m "a is dir, b is file"
hg st --all
echo % long directory replaced with file
mkdir d
mkdir d/d
echo d > d/d/d
hg commit -A -m "d is long directory"
rm -r d
echo d > d
echo % should fail - would corrupt dirstate
hg add d
echo % removing shadow
hg rm --after d/d/d
echo % should succeed - shadow removed
hg add d
hg ci -md
echo % update should work at least with clean workdir
rm -r a b d
hg up -r 0
hg st --all
rm -r a b
hg up -r 1
hg st --all
exit 0