range-diff: optionally include merge commits' diffs in the analysis
The `git log` command already offers support for including diffs for merges, via the `--diff-merges=<format>` option. Let's add corresponding support for `git range-diff`, too. This makes it more convenient to spot differences between commit ranges that contain merges. This is especially true in scenarios with non-trivial merges, i.e. merges introducing changes other than, or in addition to, what merge ORT would have produced. Merging a topic branch that changes a function signature into a branch that added a caller of that function, for example, would require the merge commit itself to adjust that caller to the modified signature. In my code reviews, I found the `--diff-merges=remerge` option particularly useful. Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de> Signed-off-by: Junio C Hamano <gitster@pobox.com>
Johannes Schindelin committed
Dec 16, 2024 at 14:11 UTC
f8043236c6c9cb9e943a87ab2e55e8e394796727
5 files changed
+50
-5
Documentation/git-range-diff.txt
+12
-1
@@ -10,7 +10,7 @@ SYNOPSIS
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[verse]
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'git range-diff' [--color=[<when>]] [--no-color] [<diff-options>]
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[--no-dual-color] [--creation-factor=<factor>]
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- [--left-only | --right-only]
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+ [--left-only | --right-only] [--diff-merges=<format>]
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( <range1> <range2> | <rev1>...<rev2> | <base> <rev1> <rev2> )
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[[--] <path>...]
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@@ -81,6 +81,17 @@ to revert to color all lines according to the outer diff markers
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Suppress commits that are missing from the second specified range
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(or the "right range" when using the `<rev1>...<rev2>` format).
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+--diff-merges=<format>::
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+ Instead of ignoring merge commits, generate diffs for them using the
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+ corresponding `--diff-merges=<format>` option of linkgit:git-log[1],
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+ and include them in the comparison.
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++
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+Note: In the common case, the `remerge` mode will be the most natural one
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+to use, as it shows only the diff on top of what Git's merge machinery would
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+have produced. In other words, if a merge commit is the result of a
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+non-conflicting `git merge`, the `remerge` mode will represent it with an empty
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+diff.
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+
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--[no-]notes[=<ref>]::
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This flag is passed to the `git log` program
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(see linkgit:git-log[1]) that generates the patches.
builtin/range-diff.c
+10
@@ -21,6 +21,7 @@ int cmd_range_diff(int argc,
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{
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struct diff_options diffopt = { NULL };
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struct strvec other_arg = STRVEC_INIT;
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+ struct strvec diff_merges_arg = STRVEC_INIT;
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struct range_diff_options range_diff_opts = {
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.creation_factor = RANGE_DIFF_CREATION_FACTOR_DEFAULT,
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.diffopt = &diffopt,
@@ -36,6 +37,8 @@ int cmd_range_diff(int argc,
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OPT_PASSTHRU_ARGV(0, "notes", &other_arg,
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N_("notes"), N_("passed to 'git log'"),
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PARSE_OPT_OPTARG),
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+ OPT_PASSTHRU_ARGV(0, "diff-merges", &diff_merges_arg,
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+ N_("style"), N_("passed to 'git log'"), 0),
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OPT_BOOL(0, "left-only", &left_only,
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N_("only emit output related to the first range")),
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OPT_BOOL(0, "right-only", &right_only,
@@ -62,6 +65,12 @@ int cmd_range_diff(int argc,
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if (!simple_color)
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diffopt.use_color = 1;
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+ /* If `--diff-merges` was specified, imply `--merges` */
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+ if (diff_merges_arg.nr) {
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+ range_diff_opts.include_merges = 1;
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+ strvec_pushv(&other_arg, diff_merges_arg.v);
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+ }
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+
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for (i = 0; i < argc; i++)
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if (!strcmp(argv[i], "--")) {
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dash_dash = i;
@@ -155,6 +164,7 @@ int cmd_range_diff(int argc,
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res = show_range_diff(range1.buf, range2.buf, &range_diff_opts);
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strvec_clear(&other_arg);
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+ strvec_clear(&diff_merges_arg);
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strbuf_release(&range1);
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strbuf_release(&range2);
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range-diff.c
+11
-4
@@ -38,7 +38,8 @@ struct patch_util {
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* as struct object_id (will need to be free()d).
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*/
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static int read_patches(const char *range, struct string_list *list,
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- const struct strvec *other_arg)
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+ const struct strvec *other_arg,
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+ unsigned int include_merges)
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{
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struct child_process cp = CHILD_PROCESS_INIT;
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struct strbuf buf = STRBUF_INIT, contents = STRBUF_INIT;
@@ -49,7 +50,7 @@ static int read_patches(const char *range, struct string_list *list,
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size_t size;
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int ret = -1;
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- strvec_pushl(&cp.args, "log", "--no-color", "-p", "--no-merges",
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+ strvec_pushl(&cp.args, "log", "--no-color", "-p",
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"--reverse", "--date-order", "--decorate=no",
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"--no-prefix", "--submodule=short",
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/*
@@ -64,6 +65,8 @@ static int read_patches(const char *range, struct string_list *list,
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"--pretty=medium",
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"--show-notes-by-default",
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NULL);
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+ if (!include_merges)
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+ strvec_push(&cp.args, "--no-merges");
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strvec_push(&cp.args, range);
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if (other_arg)
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strvec_pushv(&cp.args, other_arg->v);
@@ -96,11 +99,14 @@ static int read_patches(const char *range, struct string_list *list,
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}
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if (skip_prefix(line, "commit ", &p)) {
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+ char *q;
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if (util) {
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string_list_append(list, buf.buf)->util = util;
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strbuf_reset(&buf);
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}
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CALLOC_ARRAY(util, 1);
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+ if (include_merges && (q = strstr(p, " (from ")))
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+ *q = '\0';
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if (repo_get_oid(the_repository, p, &util->oid)) {
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error(_("could not parse commit '%s'"), p);
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FREE_AND_NULL(util);
@@ -571,13 +577,14 @@ int show_range_diff(const char *range1, const char *range2,
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struct string_list branch1 = STRING_LIST_INIT_DUP;
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struct string_list branch2 = STRING_LIST_INIT_DUP;
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+ unsigned int include_merges = range_diff_opts->include_merges;
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if (range_diff_opts->left_only && range_diff_opts->right_only)
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res = error(_("options '%s' and '%s' cannot be used together"), "--left-only", "--right-only");
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- if (!res && read_patches(range1, &branch1, range_diff_opts->other_arg))
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+ if (!res && read_patches(range1, &branch1, range_diff_opts->other_arg, include_merges))
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res = error(_("could not parse log for '%s'"), range1);
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- if (!res && read_patches(range2, &branch2, range_diff_opts->other_arg))
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+ if (!res && read_patches(range2, &branch2, range_diff_opts->other_arg, include_merges))
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res = error(_("could not parse log for '%s'"), range2);
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if (!res) {
range-diff.h
+1
@@ -16,6 +16,7 @@ struct range_diff_options {
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int creation_factor;
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unsigned dual_color:1;
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unsigned left_only:1, right_only:1;
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+ unsigned include_merges:1;
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const struct diff_options *diffopt; /* may be NULL */
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const struct strvec *other_arg; /* may be NULL */
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};
t/t3206-range-diff.sh
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@@ -909,4 +909,20 @@ test_expect_success 'submodule changes are shown irrespective of diff.submodule'
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test_cmp expect actual
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'
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+test_expect_success '--diff-merges' '
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+ renamed_oid=$(git rev-parse --short renamed-file) &&
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+ tree=$(git merge-tree unmodified renamed-file) &&
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+ clean=$(git commit-tree -m merge -p unmodified -p renamed-file $tree) &&
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+ clean_oid=$(git rev-parse --short $clean) &&
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+ conflict=$(git commit-tree -m merge -p unmodified -p renamed-file^ $tree) &&
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+ conflict_oid=$(git rev-parse --short $conflict) &&
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+
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+ git range-diff --diff-merges=1 $clean...$conflict >actual &&
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+ cat >expect <<-EOF &&
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+ 1: $renamed_oid < -: ------- s/12/B/
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+ 2: $clean_oid = 1: $conflict_oid merge
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+ EOF
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+ test_cmp expect actual
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+'
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+
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test_done