line-log: fix crash when combined with pickaxe options

queue_diffs() passes the caller's diff_options, which may carry
user-specified pickaxe state, to diff_tree_oid() and diffcore_std()
when detecting renames for line-level history tracking.  When pickaxe
options are present on the command line (-G and -S to filter by text
pattern, --find-object to filter by object identity), diffcore_std()
also runs diffcore_pickaxe(), which may discard diff pairs that are
relevant for rename detection.  Losing those pairs breaks rename
following.

Before a2bb801f6a (line-log: avoid unnecessary full tree diffs,
2019-08-21), this silently truncated history at rename boundaries.
That commit moved filter_diffs_for_paths() inside the rename-
detection block, so it only runs when diff_might_be_rename() returns
true.  When pickaxe discards a rename pair, the rename goes
undetected, and a deletion pair at a subsequent commit passes
through uncleaned, reaching process_diff_filepair() with an invalid
filespec and triggering an assertion failure.

Fix this by building a private diff_options for the rename-detection
path inside queue_diffs(), following the same pattern used by blame's
find_rename().  This isolates the rename machinery from unrelated
user-specified options.

Reported-by: Matthew Hughes <matthewhughes934@gmail.com>
Signed-off-by: Michael Montalbo <mmontalbo@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

1 files changed, 55 insertions, 0 deletions

diff --git a/t/t4211-line-log.sh b/t/t4211-line-log.sh
index 0a7c3ca42f..659a943aa1 100755
--- a/t/t4211-line-log.sh
+++ b/t/t4211-line-log.sh
@@ -367,4 +367,59 @@ test_expect_success 'show line-log with graph' '
 	test_cmp expect actual
 '
 
+test_expect_success 'setup for -L with -G/-S/--find-object and a merge with rename' '
+	git checkout --orphan pickaxe-rename &&
+	git reset --hard &&
+
+	echo content >file &&
+	git add file &&
+	git commit -m "add file" &&
+
+	git checkout -b pickaxe-rename-side &&
+	git mv file renamed-file &&
+	git commit -m "rename file" &&
+
+	git checkout pickaxe-rename &&
+	git commit --allow-empty -m "diverge" &&
+	git merge --no-edit pickaxe-rename-side &&
+
+	git mv renamed-file file &&
+	git commit -m "rename back"
+'
+
+test_expect_success '-L -G does not crash with merge and rename' '
+	git log --format="%s" --no-patch -L 1,1:file -G "." >actual
+'
+
+test_expect_success '-L -S does not crash with merge and rename' '
+	git log --format="%s" --no-patch -L 1,1:file -S content >actual
+'
+
+test_expect_success '-L --find-object does not crash with merge and rename' '
+	git log --format="%s" --no-patch -L 1,1:file \
+		--find-object=$(git rev-parse HEAD:file) >actual
+'
+
+# Commit-level filtering with pickaxe does not yet work for -L.
+# show_log() prints the commit header before diffcore_std() runs
+# pickaxe, so commits cannot be suppressed even when no diff pairs
+# survive filtering.  Fixing this would require deferring show_log()
+# until after diffcore_std(), which is a larger restructuring of the
+# log-tree output pipeline.
+test_expect_failure '-L -G should filter commits by pattern' '
+	git log --format="%s" --no-patch -L 1,1:file -G "nomatch" >actual &&
+	test_must_be_empty actual
+'
+
+test_expect_failure '-L -S should filter commits by pattern' '
+	git log --format="%s" --no-patch -L 1,1:file -S "nomatch" >actual &&
+	test_must_be_empty actual
+'
+
+test_expect_failure '-L --find-object should filter commits by object' '
+	git log --format="%s" --no-patch -L 1,1:file \
+		--find-object=$ZERO_OID >actual &&
+	test_must_be_empty actual
+'
+
 test_done