merge-recursive: avoid spurious rename/rename conflict from dir renames

If a file on one side of history was renamed, and merely modified on the other side, then applying a directory rename to the modified side gives us a rename/rename(1to2) conflict. We should only apply directory renames to pairs representing either adds or renames. Making this change means that a directory rename testcase that was previously reported as a rename/delete conflict will now be reported as a modify/delete conflict. Reviewed-by: Stefan Beller <sbeller@google.com> Signed-off-by: Elijah Newren <newren@gmail.com> Signed-off-by: Junio C Hamano <gitster@pobox.com>

Elijah Newren committed Apr 19, 2018 at 10:58 UTC 6e7e027fe5f4a8d61597a86e7f2b6087e23a759c
2 files changed +27 -32
merge-recursive.c
+2 -2
@@ -1992,7 +1992,7 @@ static void compute_collisions(struct hashmap *collisions,
1992 char *new_path;
1993 struct diff_filepair *pair = pairs->queue[i];
1994
1995 - if (pair->status == 'D')
1995 + if (pair->status != 'A' && pair->status != 'R')
1996 continue;
1997 dir_rename_ent = check_dir_renamed(pair->two->path,
1998 dir_renames);
@@ -2219,7 +2219,7 @@ static struct string_list *get_renames(struct merge_options *o,
2219 struct diff_filepair *pair = pairs->queue[i];
2220 char *new_path; /* non-NULL only with directory renames */
2221
2222 - if (pair->status == 'D') {
2222 + if (pair->status != 'A' && pair->status != 'R') {
2223 diff_free_filepair(pair);
2224 continue;
2225 }
t/t6043-merge-rename-directories.sh
+25 -30
@@ -2078,18 +2078,23 @@ test_expect_success '8b-check: Dual-directory rename, one into the others way, w
2078 )
2079 '
2080
2081 -# Testcase 8c, rename+modify/delete
2082 -# (Related to testcases 5b and 8d)
2081 +# Testcase 8c, modify/delete or rename+modify/delete?
2082 +# (Related to testcases 5b, 8d, and 9h)
2083 # Commit O: z/{b,c,d}
2084 # Commit A: y/{b,c}
2085 # Commit B: z/{b,c,d_modified,e}
2086 -# Expected: y/{b,c,e}, CONFLICT(rename+modify/delete: x/d -> y/d or deleted)
2086 +# Expected: y/{b,c,e}, CONFLICT(modify/delete: on z/d)
2087 #
2088 -# Note: This testcase doesn't present any concerns for me...until you
2089 -# compare it with testcases 5b and 8d. See notes in 8d for more
2090 -# details.
2091 -
2092 -test_expect_success '8c-setup: rename+modify/delete' '
2088 +# Note: It could easily be argued that the correct resolution here is
2089 +# y/{b,c,e}, CONFLICT(rename/delete: z/d -> y/d vs deleted)
2090 +# and that the modifed version of d should be present in y/ after
2091 +# the merge, just marked as conflicted. Indeed, I previously did
2092 +# argue that. But applying directory renames to the side of
2093 +# history where a file is merely modified results in spurious
2094 +# rename/rename(1to2) conflicts -- see testcase 9h. See also
2095 +# notes in 8d.
2096 +
2097 +test_expect_success '8c-setup: modify/delete or rename+modify/delete?' '
2098 test_create_repo 8c &&
2099 (
2100 cd 8c &&
@@ -2122,32 +2127,32 @@ test_expect_success '8c-setup: rename+modify/delete' '
2127 )
2128 '
2129
2125 -test_expect_success '8c-check: rename+modify/delete' '
2130 +test_expect_success '8c-check: modify/delete or rename+modify/delete' '
2131 (
2132 cd 8c &&
2133
2134 git checkout A^0 &&
2135
2136 test_must_fail git merge -s recursive B^0 >out &&
2132 - test_i18ngrep "CONFLICT (rename/delete).* z/d.*y/d" out &&
2137 + test_i18ngrep "CONFLICT (modify/delete).* z/d" out &&
2138
2139 git ls-files -s >out &&
2135 - test_line_count = 4 out &&
2140 + test_line_count = 5 out &&
2141 git ls-files -u >out &&
2137 - test_line_count = 1 out &&
2142 + test_line_count = 2 out &&
2143 git ls-files -o >out &&
2144 test_line_count = 1 out &&
2145
2146 git rev-parse >actual \
2142 - :0:y/b :0:y/c :0:y/e :3:y/d &&
2147 + :0:y/b :0:y/c :0:y/e :1:z/d :3:z/d &&
2148 git rev-parse >expect \
2144 - O:z/b O:z/c B:z/e B:z/d &&
2149 + O:z/b O:z/c B:z/e O:z/d B:z/d &&
2150 test_cmp expect actual &&
2151
2147 - test_must_fail git rev-parse :1:y/d &&
2148 - test_must_fail git rev-parse :2:y/d &&
2149 - git ls-files -s y/d | grep ^100755 &&
2150 - test_path_is_file y/d
2152 + test_must_fail git rev-parse :2:z/d &&
2153 + git ls-files -s z/d | grep ^100755 &&
2154 + test_path_is_file z/d &&
2155 + test_path_is_missing y/d
2156 )
2157 '
2158
@@ -2161,16 +2166,6 @@ test_expect_success '8c-check: rename+modify/delete' '
2166 #
2167 # Note: It would also be somewhat reasonable to resolve this as
2168 # y/{b,c,e}, CONFLICT(rename/delete: x/d -> y/d or deleted)
2164 -# The logic being that the only difference between this testcase and 8c
2165 -# is that there is no modification to d. That suggests that instead of a
2166 -# rename/modify vs. delete conflict, we should just have a rename/delete
2167 -# conflict, otherwise we are being inconsistent.
2168 -#
2169 -# However...as far as consistency goes, we didn't report a conflict for
2170 -# path d_1 in testcase 5b due to a different file being in the way. So,
2171 -# we seem to be forced to have cases where users can change things
2172 -# slightly and get what they may perceive as inconsistent results. It
2173 -# would be nice to avoid that, but I'm not sure I see how.
2169 #
2170 # In this case, I'm leaning towards: commit A was the one that deleted z/d
2171 # and it did the rename of z to y, so the two "conflicts" (rename vs.
@@ -2915,7 +2910,7 @@ test_expect_success '9h-setup: Avoid dir rename on merely modified path' '
2910 )
2911 '
2912
2918 -test_expect_failure '9h-check: Avoid dir rename on merely modified path' '
2913 +test_expect_success '9h-check: Avoid dir rename on merely modified path' '
2914 (
2915 cd 9h &&
2916
@@ -3959,7 +3954,7 @@ test_expect_success '12c-setup: Moving one directory hierarchy into another w/ c
3954 )
3955 '
3956
3962 -test_expect_failure '12c-check: Moving one directory hierarchy into another w/ content merge' '
3957 +test_expect_success '12c-check: Moving one directory hierarchy into another w/ content merge' '
3958 (
3959 cd 12c &&
3960