@matheusbsbs / matheus-bagliano / commits / 9d484b92ed

diff: fix interaction between the "-s" option and other options

Sergey Organov noticed and reported "--patch --no-patch --raw" behaves differently from just "--raw". It turns out that there are a few interesting bugs in the implementation and documentation. * First, the documentation for "--no-patch" was unclear that it could be read to mean "--no-patch" countermands an earlier "--patch" but not other things. The intention of "--no-patch" ever since it was introduced at d09cd15d (diff: allow --no-patch as synonym for -s, 2013-07-16) was to serve as a synonym for "-s", so "--raw --patch --no-patch" should have produced no output, but it can be (mis)read to allow showing only "--raw" output. * Then the interaction between "-s" and other format options were poorly implemented. Modern versions of Git uses one bit each to represent formatting options like "--patch", "--stat" in a single output_format word, but for historical reasons, "-s" also is represented as another bit in the same word. This allows two interesting bugs to happen, and we have both X-<. (1) After setting a format bit, then setting NO_OUTPUT with "-s", the code to process another "--<format>" option drops the NO_OUTPUT bit to allow output to be shown again. However, the code to handle "-s" only set NO_OUTPUT without unsetting format bits set earlier, so the earlier format bit got revealed upon seeing the second "--<format>" option. This is the problem Sergey observed. (2) After setting NO_OUTPUT with "-s", code to process "--<format>" option can forget to unset NO_OUTPUT, leaving the command still silent. It is tempting to change the meaning of "--no-patch" to mean "disable only the patch format output" and reimplement "-s" as "not showing anything", but it would be an end-user visible change in behavior. Let's fix the interactions of these bits to first make "-s" work as intended. The fix is conceptually very simple. * Whenever we set DIFF_FORMAT_FOO because we saw the "--foo" option (e.g. DIFF_FORMAT_RAW is set when the "--raw" option is given), we make sure we drop DIFF_FORMAT_NO_OUTPUT. We forgot to do so in some of the options and caused (2) above. * When processing "-s" option, we should not just set DIFF_FORMAT_NO_OUTPUT bit, but clear other DIFF_FORMAT_* bits. We didn't do so and retained format bits set by options previously seen, causing (1) above. It is even more tempting to lose NO_OUTPUT bit and instead take output_format word being 0 as its replacement, but that would break the mechanism "git show" uses to default to "--patch" output, where the distinction between telling the command to be silent with "-s" and having no output format specified on the command line matters, and an explicit output format given on the command line should not be "combined" with the default "--patch" format. So, while we cannot lose the NO_OUTPUT bit, as a follow-up work, we may want to replace it with OPTION_GIVEN bit, and * make "--patch", "--raw", etc. set DIFF_FORMAT_$format bit and DIFF_FORMAT_OPTION_GIVEN bit on for each format. "--no-raw", etc. will set off DIFF_FORMAT_$format bit but still record the fact that we saw an option from the command line by setting DIFF_FORMAT_OPTION_GIVEN bit. * make "-s" (and its synonym "--no-patch") clear all other bits and set only the DIFF_FORMAT_OPTION_GIVEN bit on. which I suspect would make the code much cleaner without breaking any end-user expectations. Once that is in place, transitioning "--no-patch" to mean the counterpart of "--patch", just like "--no-raw" only defeats an earlier "--raw", would be quite simple at the code level. The social cost of migrating the end-user expectations might be too great for it to be worth, but at least the "GIVEN" bit clean-up alone may be worth it. Signed-off-by: Junio C Hamano <gitster@pobox.com>

Junio C Hamano committed May 5, 2023 at 09:59 UTC 9d484b92ed38c2222b6880e0bc2b572fdc837dbd

3 files changed +51 -14

Documentation/diff-options.txt

+5 -2

@@ -29,8 +29,11 @@ endif::git-diff[]

30 -s::

31 --no-patch::

32 - Suppress diff output. Useful for commands like `git show` that

33 - show the patch by default, or to cancel the effect of `--patch`.

32 + Suppress all output from the diff machinery. Useful for

33 + commands like `git show` that show the patch by default to

34 + squelch their output, or to cancel the effect of options like

35 + `--patch`, `--stat` earlier on the command line in an alias.

36 +

37 endif::git-format-patch[]

39 ifdef::git-log[]

diff.c

+13 -11

@@ -4874,6 +4874,7 @@ static int diff_opt_stat(const struct option *opt, const char *value, int unset)

4874 } else

4875 BUG("%s should not get here", opt->long_name);

4876

4877 + options->output_format &= ~DIFF_FORMAT_NO_OUTPUT;

4878 options->output_format |= DIFF_FORMAT_DIFFSTAT;

4879 options->stat_name_width = name_width;

4880 options->stat_graph_width = graph_width;

@@ -4893,6 +4894,7 @@ static int parse_dirstat_opt(struct diff_options *options, const char *params)

4894 * The caller knows a dirstat-related option is given from the command

4895 * line; allow it to say "return this_function();"

4896 */

4897 + options->output_format &= ~DIFF_FORMAT_NO_OUTPUT;

4898 options->output_format |= DIFF_FORMAT_DIRSTAT;

4899 return 1;

4900 }

@@ -5092,6 +5094,7 @@ static int diff_opt_compact_summary(const struct option *opt,

5094 options->flags.stat_with_summary = 0;

5095 } else {

5096 options->flags.stat_with_summary = 1;

5097 + options->output_format &= ~DIFF_FORMAT_NO_OUTPUT;

5098 options->output_format |= DIFF_FORMAT_DIFFSTAT;

5099 }

5100 return 0;

@@ -5410,9 +5413,8 @@ static void prep_parse_options(struct diff_options *options)

5413 OPT_BITOP('p', "patch", &options->output_format,

5414 N_("generate patch"),

5415 DIFF_FORMAT_PATCH, DIFF_FORMAT_NO_OUTPUT),

5413 - OPT_BIT_F('s', "no-patch", &options->output_format,

5414 - N_("suppress diff output"),

5415 - DIFF_FORMAT_NO_OUTPUT, PARSE_OPT_NONEG),

5416 + OPT_SET_INT('s', "no-patch", &options->output_format,

5417 + N_("suppress diff output"), DIFF_FORMAT_NO_OUTPUT),

5418 OPT_BITOP('u', NULL, &options->output_format,

5419 N_("generate patch"),

5420 DIFF_FORMAT_PATCH, DIFF_FORMAT_NO_OUTPUT),

@@ -5421,9 +5423,9 @@ static void prep_parse_options(struct diff_options *options)

5423 PARSE_OPT_NONEG | PARSE_OPT_OPTARG, diff_opt_unified),

5424 OPT_BOOL('W', "function-context", &options->flags.funccontext,

5425 N_("generate diffs with <n> lines context")),

5424 - OPT_BIT_F(0, "raw", &options->output_format,

5426 + OPT_BITOP(0, "raw", &options->output_format,

5427 N_("generate the diff in raw format"),

5426 - DIFF_FORMAT_RAW, PARSE_OPT_NONEG),

5428 + DIFF_FORMAT_RAW, DIFF_FORMAT_NO_OUTPUT),

5429 OPT_BITOP(0, "patch-with-raw", &options->output_format,

5430 N_("synonym for '-p --raw'"),

5431 DIFF_FORMAT_PATCH | DIFF_FORMAT_RAW,

@@ -5432,12 +5434,12 @@ static void prep_parse_options(struct diff_options *options)

5434 N_("synonym for '-p --stat'"),

5435 DIFF_FORMAT_PATCH | DIFF_FORMAT_DIFFSTAT,

5436 DIFF_FORMAT_NO_OUTPUT),

5435 - OPT_BIT_F(0, "numstat", &options->output_format,

5437 + OPT_BITOP(0, "numstat", &options->output_format,

5438 N_("machine friendly --stat"),

5437 - DIFF_FORMAT_NUMSTAT, PARSE_OPT_NONEG),

5438 - OPT_BIT_F(0, "shortstat", &options->output_format,

5439 + DIFF_FORMAT_NUMSTAT, DIFF_FORMAT_NO_OUTPUT),

5440 + OPT_BITOP(0, "shortstat", &options->output_format,

5441 N_("output only the last line of --stat"),

5440 - DIFF_FORMAT_SHORTSTAT, PARSE_OPT_NONEG),

5442 + DIFF_FORMAT_SHORTSTAT, DIFF_FORMAT_NO_OUTPUT),

5443 OPT_CALLBACK_F('X', "dirstat", options, N_("<param1,param2>..."),

5444 N_("output the distribution of relative amount of changes for each sub-directory"),

5445 PARSE_OPT_NONEG | PARSE_OPT_OPTARG,

@@ -5453,9 +5455,9 @@ static void prep_parse_options(struct diff_options *options)

5455 OPT_BIT_F(0, "check", &options->output_format,

5456 N_("warn if changes introduce conflict markers or whitespace errors"),

5457 DIFF_FORMAT_CHECKDIFF, PARSE_OPT_NONEG),

5456 - OPT_BIT_F(0, "summary", &options->output_format,

5458 + OPT_BITOP(0, "summary", &options->output_format,

5459 N_("condensed summary such as creations, renames and mode changes"),

5458 - DIFF_FORMAT_SUMMARY, PARSE_OPT_NONEG),

5460 + DIFF_FORMAT_SUMMARY, DIFF_FORMAT_NO_OUTPUT),

5461 OPT_BIT_F(0, "name-only", &options->output_format,

5462 N_("show only names of changed files"),

5463 DIFF_FORMAT_NAME, PARSE_OPT_NONEG),

t/t4000-diff-format.sh

+33 -1

@@ -5,6 +5,9 @@

6 test_description='Test built-in diff output engine.

8 +We happen to know that all diff plumbing and diff Porcelain share the

9 +same command line parser, so testing one should be sufficient; pick

10 +diff-files as a representative.

11 '

13 TEST_PASSES_SANITIZE_LEAK=true

@@ -16,9 +19,11 @@ Line 2

19 line 3'

20 cat path0 >path1

21 chmod +x path1

22 +mkdir path2

23 +>path2/path3

25 test_expect_success 'update-index --add two files with and without +x.' '

21 - git update-index --add path0 path1

26 + git update-index --add path0 path1 path2/path3

27 '

29 mv path0 path0-

@@ -91,4 +96,31 @@ test_expect_success 'git diff-files --patch --no-patch does not show the patch'

96 test_must_be_empty err

97 '

99 +

100 +# Smudge path2/path3 so that dirstat has something to show

101 +date >path2/path3

102 +

103 +for format in stat raw numstat shortstat summary \

104 + dirstat cumulative dirstat-by-file \

105 + patch-with-raw patch-with-stat compact-summary

106 +do

107 + test_expect_success "--no-patch in 'git diff-files --no-patch --$format' is a no-op" '

108 + git diff-files --no-patch "--$format" >actual &&

109 + git diff-files "--$format" >expect &&

110 + test_cmp expect actual

111 + '

112 +

113 + test_expect_success "--no-patch clears all previous ones" '

114 + git diff-files --$format -s -p >actual &&

115 + git diff-files -p >expect &&

116 + test_cmp expect actual

117 + '

118 +

119 + test_expect_success "--no-patch in 'git diff --no-patch --$format' is a no-op" '

120 + git diff --no-patch "--$format" >actual &&

121 + git diff "--$format" >expect &&

122 + test_cmp expect actual

123 + '

124 +done

125 +

126 test_done