No diff -b/-w output for all-whitespace changes

Change git-diff's whitespace-ignoring modes to generate
output only if a non-empty patch results, which git-apply
rejects.

Update the tests to look for the new behavior.

Signed-off-by: Greg Bacon <gbacon@dbresearch.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

diff --git a/diff.c b/diff.c
index 0d7f5ea4a87d2152638f36b30d6366406d33bfa9..108de236114ab98bf4eb03680d66b22e604cba32 100644 (file)
--- a/diff.c
+++ b/diff.c
@@ -189,6 +189,7 @@ struct emit_callback {
        struct diff_words_data *diff_words;
        int *found_changesp;
        FILE *file;
+       struct strbuf *header;
 };
 
 static int count_lines(const char *data, int size)
@@ -755,6 +756,11 @@ static void fn_out_consume(void *priv, char *line, unsigned long len)
        const char *plain = diff_get_color(ecbdata->color_diff, DIFF_PLAIN);
        const char *reset = diff_get_color(ecbdata->color_diff, DIFF_RESET);
 
+       if (ecbdata->header) {
+               fprintf(ecbdata->file, "%s", ecbdata->header->buf);
+               strbuf_reset(ecbdata->header);
+               ecbdata->header = NULL;
+       }
        *(ecbdata->found_changesp) = 1;
 
        if (ecbdata->label_path[0]) {
@@ -1561,6 +1567,7 @@ static void builtin_diff(const char *name_a,
        const char *reset = diff_get_color_opt(o, DIFF_RESET);
        const char *a_prefix, *b_prefix;
        const char *textconv_one = NULL, *textconv_two = NULL;
+       struct strbuf header = STRBUF_INIT;
 
        if (DIFF_OPT_TST(o, SUBMODULE_LOG) &&
                        (!one->mode || S_ISGITLINK(one->mode)) &&
@@ -1595,25 +1602,26 @@ static void builtin_diff(const char *name_a,
        b_two = quote_two(b_prefix, name_b + (*name_b == '/'));
        lbl[0] = DIFF_FILE_VALID(one) ? a_one : "/dev/null";
        lbl[1] = DIFF_FILE_VALID(two) ? b_two : "/dev/null";
-       fprintf(o->file, "%sdiff --git %s %s%s\n", set, a_one, b_two, reset);
+       strbuf_addf(&header, "%sdiff --git %s %s%s\n", set, a_one, b_two, reset);
        if (lbl[0][0] == '/') {
                /* /dev/null */
-               fprintf(o->file, "%snew file mode %06o%s\n", set, two->mode, reset);
+               strbuf_addf(&header, "%snew file mode %06o%s\n", set, two->mode, reset);
                if (xfrm_msg && xfrm_msg[0])
-                       fprintf(o->file, "%s%s%s\n", set, xfrm_msg, reset);
+                       strbuf_addf(&header, "%s%s%s\n", set, xfrm_msg, reset);
        }
        else if (lbl[1][0] == '/') {
-               fprintf(o->file, "%sdeleted file mode %06o%s\n", set, one->mode, reset);
+               strbuf_addf(&header, "%sdeleted file mode %06o%s\n", set, one->mode, reset);
                if (xfrm_msg && xfrm_msg[0])
-                       fprintf(o->file, "%s%s%s\n", set, xfrm_msg, reset);
+                       strbuf_addf(&header, "%s%s%s\n", set, xfrm_msg, reset);
        }
        else {
                if (one->mode != two->mode) {
-                       fprintf(o->file, "%sold mode %06o%s\n", set, one->mode, reset);
-                       fprintf(o->file, "%snew mode %06o%s\n", set, two->mode, reset);
+                       strbuf_addf(&header, "%sold mode %06o%s\n", set, one->mode, reset);
+                       strbuf_addf(&header, "%snew mode %06o%s\n", set, two->mode, reset);
                }
                if (xfrm_msg && xfrm_msg[0])
-                       fprintf(o->file, "%s%s%s\n", set, xfrm_msg, reset);
+                       strbuf_addf(&header, "%s%s%s\n", set, xfrm_msg, reset);
+
                /*
                 * we do not run diff between different kind
                 * of objects.
@@ -1623,6 +1631,8 @@ static void builtin_diff(const char *name_a,
                if (complete_rewrite &&
                    (textconv_one || !diff_filespec_is_binary(one)) &&
                    (textconv_two || !diff_filespec_is_binary(two))) {
+                       fprintf(o->file, "%s", header.buf);
+                       strbuf_reset(&header);
                        emit_rewrite_diff(name_a, name_b, one, two,
                                                textconv_one, textconv_two, o);
                        o->found_changes = 1;
@@ -1640,6 +1650,8 @@ static void builtin_diff(const char *name_a,
                if (mf1.size == mf2.size &&
                    !memcmp(mf1.ptr, mf2.ptr, mf1.size))
                        goto free_ab_and_return;
+               fprintf(o->file, "%s", header.buf);
+               strbuf_reset(&header);
                if (DIFF_OPT_TST(o, BINARY))
                        emit_binary_diff(o->file, &mf1, &mf2);
                else
@@ -1656,6 +1668,11 @@ static void builtin_diff(const char *name_a,
                struct emit_callback ecbdata;
                const struct userdiff_funcname *pe;
 
+               if (!DIFF_XDL_TST(o, WHITESPACE_FLAGS)) {
+                       fprintf(o->file, "%s", header.buf);
+                       strbuf_reset(&header);
+               }
+
                if (textconv_one) {
                        size_t size;
                        mf1.ptr = run_textconv(textconv_one, one, &size);
@@ -1685,6 +1702,7 @@ static void builtin_diff(const char *name_a,
                if (ecbdata.ws_rule & WS_BLANK_AT_EOF)
                        check_blank_at_eof(&mf1, &mf2, &ecbdata);
                ecbdata.file = o->file;
+               ecbdata.header = header.len ? &header : NULL;
                xpp.flags = XDF_NEED_MINIMAL | o->xdl_opts;
                xecfg.ctxlen = o->context;
                xecfg.interhunkctxlen = o->interhunkcontext;
@@ -1729,6 +1747,7 @@ static void builtin_diff(const char *name_a,
        }
 
  free_ab_and_return:
+       strbuf_release(&header);
        diff_free_filespec_data(one);
        diff_free_filespec_data(two);
        free(a_one);

diff --git a/t/t4015-diff-whitespace.sh b/t/t4015-diff-whitespace.sh
index 8dd147d78f6ee6a4be4b1af235ed35af19b273df..90f33423731a84310caf92780482a44f8d2f32d8 100755 (executable)
--- a/t/t4015-diff-whitespace.sh
+++ b/t/t4015-diff-whitespace.sh
@@ -93,8 +93,6 @@ git diff > out
 test_expect_success 'another test, without options' 'test_cmp expect out'
 
 cat << EOF > expect
-diff --git a/x b/x
-index d99af23..8b32fb5 100644
 EOF
 git diff -w > out
 test_expect_success 'another test, with -w' 'test_cmp expect out'
@@ -386,6 +384,18 @@ test_expect_success 'checkdiff allows new blank lines' '
        git diff --check
 '
 
+cat <<EOF >expect
+EOF
+test_expect_success 'whitespace-only changes not reported' '
+       git reset --hard &&
+       echo >x "hello world" &&
+       git add x &&
+       git commit -m "hello 1" &&
+       echo >x "hello  world" &&
+       git diff -b >actual &&
+       test_cmp expect actual
+'
+
 test_expect_success 'combined diff with autocrlf conversion' '
 
        git reset --hard &&