diff-filter: be more careful when looking for negative bits

The `--diff-filter=<bits>` option allows to filter the diff by certain
criteria, for example `R` to only show renamed files. It also supports
negating a filter via a down-cased letter, i.e. `r` to show _everything
but_ renamed files.

However, the code is a bit overzealous when trying to figure out whether
`git diff` should start with all diff-filters turned on because the user
provided a lower-case letter: if the `--diff-filter` argument starts
with an upper-case letter, we must not start with all bits turned on.

Even worse, it is possible to specify the diff filters in multiple,
separate options, e.g. `--diff-filter=AM [...] --diff-filter=m`.

Let's accumulate the include/exclude filters independently, and only
special-case the "only exclude filters were specified" case after
parsing the options altogether.

Note: The code replaced by this commit took pains to avoid setting any
unused bits of `options->filter`. That was unnecessary, though, as all
accesses happen via the `filter_bit_tst()` function using specific bits,
and setting the unused bits has no effect. Therefore, we can simplify
the code by using `~0` (or in this instance, `~<unwanted-bit>`).

Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

diff --git a/diff.c b/diff.c
index 5081052c431b276af7ed4a8f898b073593febb45..4ab4299b817392ca281b22ad4b513c92b0193957 100644 (file)
--- a/diff.c
+++ b/diff.c
@@ -4720,6 +4720,12 @@ void diff_setup_done(struct diff_options *options)
        if (!options->use_color || external_diff())
                options->color_moved = 0;
 
+       if (options->filter_not) {
+               if (!options->filter)
+                       options->filter = ~filter_bit[DIFF_STATUS_FILTER_AON];
+               options->filter &= ~options->filter_not;
+       }
+
        FREE_AND_NULL(options->parseopts);
 }
 
@@ -4820,21 +4826,6 @@ static int diff_opt_diff_filter(const struct option *option,
        BUG_ON_OPT_NEG(unset);
        prepare_filter_bits();
 
-       /*
-        * If there is a negation e.g. 'd' in the input, and we haven't
-        * initialized the filter field with another --diff-filter, start
-        * from full set of bits, except for AON.
-        */
-       if (!opt->filter) {
-               for (i = 0; (optch = optarg[i]) != '\0'; i++) {
-                       if (optch < 'a' || 'z' < optch)
-                               continue;
-                       opt->filter = (1 << (ARRAY_SIZE(diff_status_letters) - 1)) - 1;
-                       opt->filter &= ~filter_bit[DIFF_STATUS_FILTER_AON];
-                       break;
-               }
-       }
-
        for (i = 0; (optch = optarg[i]) != '\0'; i++) {
                unsigned int bit;
                int negate;
@@ -4851,7 +4842,7 @@ static int diff_opt_diff_filter(const struct option *option,
                        return error(_("unknown change class '%c' in --diff-filter=%s"),
                                     optarg[i], optarg);
                if (negate)
-                       opt->filter &= ~bit;
+                       opt->filter_not |= bit;
                else
                        opt->filter |= bit;
        }

diff --git a/diff.h b/diff.h
index 8ba85c5e60562b081ad7c12ddcddbd37e2004551..a70e7c478c1b5852cfef72a967a839df6e50e4b9 100644 (file)
--- a/diff.h
+++ b/diff.h
@@ -283,7 +283,7 @@ struct diff_options {
        struct diff_flags flags;
 
        /* diff-filter bits */
-       unsigned int filter;
+       unsigned int filter, filter_not;
 
        int use_color;
 

diff --git a/t/t4202-log.sh b/t/t4202-log.sh
index 504955986197224ecc41c15e52fea98a021b9f00..b25182379ff160e6ec80e3d8787cc566640bf8f5 100755 (executable)
--- a/t/t4202-log.sh
+++ b/t/t4202-log.sh
@@ -142,6 +142,19 @@ test_expect_success 'diff-filter=R' '
 
 '
 
+test_expect_success 'multiple --diff-filter bits' '
+
+       git log -M --pretty="format:%s" --diff-filter=R HEAD >expect &&
+       git log -M --pretty="format:%s" --diff-filter=Ra HEAD >actual &&
+       test_cmp expect actual &&
+       git log -M --pretty="format:%s" --diff-filter=aR HEAD >actual &&
+       test_cmp expect actual &&
+       git log -M --pretty="format:%s" \
+               --diff-filter=a --diff-filter=R HEAD >actual &&
+       test_cmp expect actual
+
+'
+
 test_expect_success 'diff-filter=C' '
 
        git log -C -C --pretty="format:%s" --diff-filter=C HEAD >actual &&