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
index fbdbe0befe..00c649b140 100644
--- a/Documentation/git-range-diff.txt
+++ b/Documentation/git-range-diff.txt
@@ -10,7 +10,7 @@ SYNOPSIS
[verse]
'git range-diff' [--color=[<when>]] [--no-color] [<diff-options>]
[--no-dual-color] [--creation-factor=<factor>]
- [--left-only | --right-only]
+ [--left-only | --right-only] [--diff-merges=<format>]
( <range1> <range2> | <rev1>...<rev2> | <base> <rev1> <rev2> )
[[--] <path>...]
@@ -81,6 +81,17 @@ to revert to color all lines according to the outer diff markers
Suppress commits that are missing from the second specified range
(or the "right range" when using the `<rev1>...<rev2>` format).
+--diff-merges=<format>::
+ Instead of ignoring merge commits, generate diffs for them using the
+ corresponding `--diff-merges=<format>` option of linkgit:git-log[1],
+ and include them in the comparison.
++
+Note: In the common case, the `remerge` mode will be the most natural one
+to use, as it shows only the diff on top of what Git's merge machinery would
+have produced. In other words, if a merge commit is the result of a
+non-conflicting `git merge`, the `remerge` mode will represent it with an empty
+diff.
+
--[no-]notes[=<ref>]::
This flag is passed to the `git log` program
(see linkgit:git-log[1]) that generates the patches.
builtin/range-diff.c
+10
index 1b33ab66a7..901de5d133 100644
--- a/builtin/range-diff.c
+++ b/builtin/range-diff.c
@@ -21,6 +21,7 @@ int cmd_range_diff(int argc,
{
struct diff_options diffopt = { NULL };
struct strvec other_arg = STRVEC_INIT;
+ struct strvec diff_merges_arg = STRVEC_INIT;
struct range_diff_options range_diff_opts = {
.creation_factor = RANGE_DIFF_CREATION_FACTOR_DEFAULT,
.diffopt = &diffopt,
@@ -36,6 +37,8 @@ int cmd_range_diff(int argc,
OPT_PASSTHRU_ARGV(0, "notes", &other_arg,
N_("notes"), N_("passed to 'git log'"),
PARSE_OPT_OPTARG),
+ OPT_PASSTHRU_ARGV(0, "diff-merges", &diff_merges_arg,
+ N_("style"), N_("passed to 'git log'"), 0),
OPT_BOOL(0, "left-only", &left_only,
N_("only emit output related to the first range")),
OPT_BOOL(0, "right-only", &right_only,
@@ -62,6 +65,12 @@ int cmd_range_diff(int argc,
if (!simple_color)
diffopt.use_color = 1;
+ /* If `--diff-merges` was specified, imply `--merges` */
+ if (diff_merges_arg.nr) {
+ range_diff_opts.include_merges = 1;
+ strvec_pushv(&other_arg, diff_merges_arg.v);
+ }
+
for (i = 0; i < argc; i++)
if (!strcmp(argv[i], "--")) {
dash_dash = i;
@@ -155,6 +164,7 @@ int cmd_range_diff(int argc,
res = show_range_diff(range1.buf, range2.buf, &range_diff_opts);
strvec_clear(&other_arg);
+ strvec_clear(&diff_merges_arg);
strbuf_release(&range1);
strbuf_release(&range2);
range-diff.c
+11
-4
index 10885ba301..19673d47d9 100644
--- a/range-diff.c
+++ b/range-diff.c
@@ -38,7 +38,8 @@ struct patch_util {
* as struct object_id (will need to be free()d).
*/
static int read_patches(const char *range, struct string_list *list,
- const struct strvec *other_arg)
+ const struct strvec *other_arg,
+ unsigned int include_merges)
{
struct child_process cp = CHILD_PROCESS_INIT;
struct strbuf buf = STRBUF_INIT, contents = STRBUF_INIT;
@@ -49,7 +50,7 @@ static int read_patches(const char *range, struct string_list *list,
size_t size;
int ret = -1;
- strvec_pushl(&cp.args, "log", "--no-color", "-p", "--no-merges",
+ strvec_pushl(&cp.args, "log", "--no-color", "-p",
"--reverse", "--date-order", "--decorate=no",
"--no-prefix", "--submodule=short",
/*
@@ -64,6 +65,8 @@ static int read_patches(const char *range, struct string_list *list,
"--pretty=medium",
"--show-notes-by-default",
NULL);
+ if (!include_merges)
+ strvec_push(&cp.args, "--no-merges");
strvec_push(&cp.args, range);
if (other_arg)
strvec_pushv(&cp.args, other_arg->v);
@@ -96,11 +99,14 @@ static int read_patches(const char *range, struct string_list *list,
}
if (skip_prefix(line, "commit ", &p)) {
+ char *q;
if (util) {
string_list_append(list, buf.buf)->util = util;
strbuf_reset(&buf);
}
CALLOC_ARRAY(util, 1);
+ if (include_merges && (q = strstr(p, " (from ")))
+ *q = '\0';
if (repo_get_oid(the_repository, p, &util->oid)) {
error(_("could not parse commit '%s'"), p);
FREE_AND_NULL(util);
@@ -571,13 +577,14 @@ int show_range_diff(const char *range1, const char *range2,
struct string_list branch1 = STRING_LIST_INIT_DUP;
struct string_list branch2 = STRING_LIST_INIT_DUP;
+ unsigned int include_merges = range_diff_opts->include_merges;
if (range_diff_opts->left_only && range_diff_opts->right_only)
res = error(_("options '%s' and '%s' cannot be used together"), "--left-only", "--right-only");
- if (!res && read_patches(range1, &branch1, range_diff_opts->other_arg))
+ if (!res && read_patches(range1, &branch1, range_diff_opts->other_arg, include_merges))
res = error(_("could not parse log for '%s'"), range1);
- if (!res && read_patches(range2, &branch2, range_diff_opts->other_arg))
+ if (!res && read_patches(range2, &branch2, range_diff_opts->other_arg, include_merges))
res = error(_("could not parse log for '%s'"), range2);
if (!res) {
range-diff.h
+1
index 2f69f6a434..cd85000b5a 100644
--- a/range-diff.h
+++ b/range-diff.h
@@ -16,6 +16,7 @@ struct range_diff_options {
int creation_factor;
unsigned dual_color:1;
unsigned left_only:1, right_only:1;
+ unsigned include_merges:1;
const struct diff_options *diffopt; /* may be NULL */
const struct strvec *other_arg; /* may be NULL */
};
t/t3206-range-diff.sh
+16
index 86010931ab..c18a3fdab8 100755
--- a/t/t3206-range-diff.sh
+++ b/t/t3206-range-diff.sh
@@ -909,4 +909,20 @@ test_expect_success 'submodule changes are shown irrespective of diff.submodule'
test_cmp expect actual
'
+test_expect_success '--diff-merges' '
+ renamed_oid=$(git rev-parse --short renamed-file) &&
+ tree=$(git merge-tree unmodified renamed-file) &&
+ clean=$(git commit-tree -m merge -p unmodified -p renamed-file $tree) &&
+ clean_oid=$(git rev-parse --short $clean) &&
+ conflict=$(git commit-tree -m merge -p unmodified -p renamed-file^ $tree) &&
+ conflict_oid=$(git rev-parse --short $conflict) &&
+
+ git range-diff --diff-merges=1 $clean...$conflict >actual &&
+ cat >expect <<-EOF &&
+ 1: $renamed_oid < -: ------- s/12/B/
+ 2: $clean_oid = 1: $conflict_oid merge
+ EOF
+ test_cmp expect actual
+'
+
test_done