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
echo "[ui]" >> $HGRCPATH
echo "interactive=true" >> $HGRCPATH
echo "[extensions]" >> $HGRCPATH
echo "record=" >> $HGRCPATH
echo "% help (no mq, so no qrecord)"
hg help qrecord
echo "mq=" >> $HGRCPATH
echo "% help (mq present)"
hg help qrecord
hg init a
cd a
echo % base commit
cat > 1.txt <<EOF
1
2
3
4
5
EOF
cat > 2.txt <<EOF
a
b
c
d
e
f
EOF
mkdir dir
cat > dir/a.txt <<EOF
hello world
someone
up
there
loves
me
EOF
hg add 1.txt 2.txt dir/a.txt
hg commit -m 'initial checkin'
echo % changing files
sed -e 's/2/2 2/;s/4/4 4/' 1.txt > 1.txt.new
sed -e 's/b/b b/' 2.txt > 2.txt.new
sed -e 's/hello world/hello world!/' dir/a.txt > dir/a.txt.new
mv -f 1.txt.new 1.txt
mv -f 2.txt.new 2.txt
mv -f dir/a.txt.new dir/a.txt
echo % whole diff
hg diff --nodates
echo % qrecord a.patch
hg qrecord -d '0 0' -m aaa a.patch <<EOF
y
y
n
y
y
n
EOF
echo
echo % "after qrecord a.patch 'tip'"
hg tip -p
echo
echo % "after qrecord a.patch 'diff'"
hg diff --nodates
echo % qrecord b.patch
hg qrecord -d '0 0' -m bbb b.patch <<EOF
y
y
y
y
EOF
echo
echo % "after qrecord b.patch 'tip'"
hg tip -p
echo
echo % "after qrecord b.patch 'diff'"
hg diff --nodates
echo
echo % --- end ---