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authorJeff King <>2016-01-19 22:07:22 (GMT)
committerJunio C Hamano <>2016-01-19 22:20:56 (GMT)
commit1dc413ebe52bd5dffed63d69a0a239b7fb6ef699 (patch)
tree4c98d6dc250eab9d68d7b5dcbf3b4e3bc42545f5 /
parent348d4f2fc5d3c4f7ba47079b96676b4e2dd831fc (diff)
filter-branch: resolve $commit^{tree} in no-index case
Commit 348d4f2 (filter-branch: skip index read/write when possible, 2015-11-06) taught filter-branch to optimize out the final "git write-tree" when we know we haven't touched the tree with any of our filters. It does by simply putting the literal text "$commit^{tree}" into the "$tree" variable, avoiding a useless rev-parse call. However, when we pass this to git_commit_non_empty_tree(), it gets confused; it resolves "$commit^{tree}" itself, and compares our string to the 40-hex sha1, which obviously doesn't match. As a result, "--prune-empty" (or any custom filter using git_commit_non_empty_tree) will fail to drop an empty commit (when filter-branch is used without a tree or index filter). Let's resolve $tree to the 40-hex ourselves, so that git_commit_non_empty_tree can work. Unfortunately, this is a bit slower due to the extra process overhead: $ cd t/perf && ./run 348d4f2 HEAD [...] Test 348d4f2 HEAD -------------------------------------------------------------- 7000.2: noop filter 3.76(0.24+0.26) 4.54(0.28+0.24) +20.7% We could try to make git_commit_non_empty_tree more clever. However, the value of $tree here is technically user-visible. The user can provide arbitrary shell code at this stage, which could itself have a similar assumption to what is in git_commit_non_empty_tree. So the conservative choice to fix this regression is to take the 20% hit and give the pre-348d4f2 behavior. We still end up much faster than before the optimization: $ cd t/perf && ./run 348d4f2^ HEAD [...] Test 348d4f2^ HEAD -------------------------------------------------------------- 7000.2: noop filter 9.51(4.32+0.40) 4.51(0.28+0.23) -52.6% Signed-off-by: Jeff King <> Signed-off-by: Junio C Hamano <>
Diffstat (limited to '')
1 files changed, 1 insertions, 1 deletions
diff --git a/ b/
index d61f9ba..5e094ce 100755
--- a/
+++ b/
@@ -404,7 +404,7 @@ while read commit parents; do
tree=$(git write-tree)
- tree="$commit^{tree}"
+ tree=$(git rev-parse "$commit^{tree}")
workdir=$workdir @SHELL_PATH@ -c "$filter_commit" "git commit-tree" \
"$tree" $parentstr < ../message > ../map/$commit ||