| Message ID | YEj8zy5JX+KvlfGJ@coredump.intra.peff.net (mailing list archive) |
|---|---|
| State | Accepted |
| Commit | 98fe9e666fe4a595cf5396fd8d5c57b380c782b2 |
| Headers | show |
| Series | sha256 fixes for filter-branch | expand |
Jeff King <peff@peff.net> writes: > When a ref maps to a commit that is neither rewritten nor kept by > filter-branch (e.g., because it was eliminated by rev-list's pathspec > selection), we rewrite it to its nearest ancestor. > > Since the initial commit in 6f6826c52b (Add git-filter-branch, > 2007-06-03), we have warned when there are multiple such ancestors in > the map file. However, the warning code is impossible to trigger these > days. Since a0e46390d3 (filter-branch: fix ref rewriting with > --subdirectory-filter, 2008-08-12), we find the ancestor using "rev-list > -1", so it can only ever have a single value. ;-)
diff --git a/git-filter-branch.sh b/git-filter-branch.sh index fea7964617..a1e80bd552 100755 --- a/git-filter-branch.sh +++ b/git-filter-branch.sh @@ -492,7 +492,7 @@ then sha1=$(git rev-parse "$ref"^0) test -f "$workdir"/../map/$sha1 && continue ancestor=$(git rev-list --simplify-merges -1 "$ref" "$@") - test "$ancestor" && echo $(map $ancestor) >> "$workdir"/../map/$sha1 + test "$ancestor" && echo $(map $ancestor) >"$workdir"/../map/$sha1 done < "$tempdir"/heads fi @@ -534,14 +534,7 @@ do fi ;; *) - # NEEDSWORK: possibly add -Werror, making this an error - warn "WARNING: '$ref' was rewritten into multiple commits:" - warn "$rewritten" - warn "WARNING: Ref '$ref' points to the first one now." - rewritten=$(echo "$rewritten" | head -n 1) - git update-ref -m "filter-branch: rewrite to first" \ - "$ref" $rewritten $sha1 || - die "Could not rewrite $ref" + die "BUG: multiple ancestors in map file?" ;; esac git update-ref -m "filter-branch: backup" "$orig_namespace$ref" $sha1 ||
When a ref maps to a commit that is neither rewritten nor kept by filter-branch (e.g., because it was eliminated by rev-list's pathspec selection), we rewrite it to its nearest ancestor. Since the initial commit in 6f6826c52b (Add git-filter-branch, 2007-06-03), we have warned when there are multiple such ancestors in the map file. However, the warning code is impossible to trigger these days. Since a0e46390d3 (filter-branch: fix ref rewriting with --subdirectory-filter, 2008-08-12), we find the ancestor using "rev-list -1", so it can only ever have a single value. This code is made doubly confusing by the fact that we append to the map file when mapping ancestors. However, this can never yield multiple values because: - we explicitly check whether the map already exists, and if so, do nothing (so our "append" will always be to a file that does not exist) - even if we were to try mapping twice, the process to do so is deterministic. I.e., we'd always end up with the same ancestor for a given sha1. So warning about it would be pointless; there is no ambiguity. So swap out the warning code for a BUG (which we'll simplify further in the next commit). And let's stop using the append operator to make the ancestor-mapping code less confusing. Signed-off-by: Jeff King <peff@peff.net> --- git-filter-branch.sh | 11 ++--------- 1 file changed, 2 insertions(+), 9 deletions(-)