@matheusbsbs / matheus-bagliano / commits / f8246281af

merge: use editor by default in interactive sessions

Traditionally, a cleanly resolved merge was committed by "git merge" using the auto-generated merge commit log message without invoking the editor. After 5 years of use in the field, it turns out that people perform too many unjustified merges of the upstream history into their topic branches. These merges are not just useless, but they are often not explained well, and making the end result unreadable when it gets time for merging their history back to their upstream. Earlier we added the "--edit" option to the command, so that people can edit the log message to explain and justify their merge commits. Let's take it one step further and spawn the editor by default when we are in an interactive session (i.e. the standard input and the standard output are pointing at the same tty device). There may be existing scripts that leave the standard input and the standard output of the "git merge" connected to whatever environment the scripts were started, and such invocation might trigger the above "interactive session" heuristics. GIT_MERGE_AUTOEDIT environment variable can be set to "no" at the beginning of such scripts to use the historical behaviour while the script runs. Note that this backward compatibility is meant only for scripts, and we deliberately do *not* support "merge.edit = yes/no/auto" configuration option to allow people to keep the historical behaviour. Suggested-by: Linus Torvalds <torvalds@linux-foundation.org> Signed-off-by: Junio C Hamano <gitster@pobox.com>

Junio C Hamano committed Jan 10, 2012 at 22:44 UTC f8246281af9adb0fdddbcc90d2e19cb5cd5217e5
4 files changed +50 -9
Documentation/git-merge.txt
+1 -1
@@ -9,7 +9,7 @@ git-merge - Join two or more development histories together
9 SYNOPSIS
10 --------
11 [verse]
12 -'git merge' [-n] [--stat] [--no-commit] [--squash]
12 +'git merge' [-n] [--stat] [--no-commit] [--squash] [--[no-]edit]
13 [-s <strategy>] [-X <strategy-option>]
14 [--[no-]rerere-autoupdate] [-m <msg>] [<commit>...]
15 'git merge' <msg> HEAD <commit>...
Documentation/merge-options.txt
+13 -3
@@ -8,10 +8,20 @@ failed and do not autocommit, to give the user a chance to
8 inspect and further tweak the merge result before committing.
9
10 --edit::
11 --e::
11 +--no-edit::
12 + Invoke an editor before committing successful mechanical merge to
13 + further edit the auto-generated merge message, so that the user
14 + can explain and justify the merge. The `--no-edit` option can be
15 + used to accept the auto-generated message (this is generally
16 + discouraged). The `--edit` option is still useful if you are
17 + giving a draft message with the `-m` option from the command line
18 + and want to edit it in the editor.
19 +
13 - Invoke editor before committing successful merge to further
14 - edit the default merge message.
20 +Older scripts may depend on the historical behaviour of not allowing the
21 +user to edit the merge log message. They will see an editor opened when
22 +they run `git merge`. To make it easier to adjust such scripts to the
23 +updated behaviour, the environment variable `GIT_MERGE_AUTOEDIT` can be
24 +set to `no` at the beginning of them.
25
26 --ff::
27 --no-ff::
builtin/merge.c
+34 -4
@@ -46,7 +46,7 @@ static const char * const builtin_merge_usage[] = {
46
47 static int show_diffstat = 1, shortlog_len, squash;
48 static int option_commit = 1, allow_fast_forward = 1;
49 -static int fast_forward_only, option_edit;
49 +static int fast_forward_only, option_edit = -1;
50 static int allow_trivial = 1, have_message;
51 static struct strbuf merge_msg;
52 static struct commit_list *remoteheads;
@@ -189,7 +189,7 @@ static struct option builtin_merge_options[] = {
189 "create a single commit instead of doing a merge"),
190 OPT_BOOLEAN(0, "commit", &option_commit,
191 "perform a commit if the merge succeeds (default)"),
192 - OPT_BOOLEAN('e', "edit", &option_edit,
192 + OPT_BOOL('e', "edit", &option_edit,
193 "edit message before committing"),
194 OPT_BOOLEAN(0, "ff", &allow_fast_forward,
195 "allow fast-forward (default)"),
@@ -877,12 +877,12 @@ static void prepare_to_commit(void)
877 write_merge_msg(&msg);
878 run_hook(get_index_file(), "prepare-commit-msg",
879 git_path("MERGE_MSG"), "merge", NULL, NULL);
880 - if (option_edit) {
880 + if (0 < option_edit) {
881 if (launch_editor(git_path("MERGE_MSG"), NULL, NULL))
882 abort_commit(NULL);
883 }
884 read_merge_msg(&msg);
885 - stripspace(&msg, option_edit);
885 + stripspace(&msg, 0 < option_edit);
886 if (!msg.len)
887 abort_commit(_("Empty commit message."));
888 strbuf_release(&merge_msg);
@@ -1076,6 +1076,33 @@ static void write_merge_state(void)
1076 close(fd);
1077 }
1078
1079 +static int default_edit_option(void)
1080 +{
1081 + static const char name[] = "GIT_MERGE_AUTOEDIT";
1082 + const char *e = getenv(name);
1083 + struct stat st_stdin, st_stdout;
1084 +
1085 + if (have_message)
1086 + /* an explicit -m msg without --[no-]edit */
1087 + return 0;
1088 +
1089 + if (e) {
1090 + int v = git_config_maybe_bool(name, e);
1091 + if (v < 0)
1092 + die("Bad value '%s' in environment '%s'", e, name);
1093 + return v;
1094 + }
1095 +
1096 + /* Use editor if stdin and stdout are the same and is a tty */
1097 + return (!fstat(0, &st_stdin) &&
1098 + !fstat(1, &st_stdout) &&
1099 + isatty(0) &&
1100 + st_stdin.st_dev == st_stdout.st_dev &&
1101 + st_stdin.st_ino == st_stdout.st_ino &&
1102 + st_stdin.st_mode == st_stdout.st_mode);
1103 +}
1104 +
1105 +
1106 int cmd_merge(int argc, const char **argv, const char *prefix)
1107 {
1108 unsigned char result_tree[20];
@@ -1261,6 +1288,9 @@ int cmd_merge(int argc, const char **argv, const char *prefix)
1288 }
1289 }
1290
1291 + if (option_edit < 0)
1292 + option_edit = default_edit_option();
1293 +
1294 if (!use_strategies) {
1295 if (!remoteheads->next)
1296 add_strategies(pull_twohead, DEFAULT_TWOHEAD);
t/test-lib.sh
+2 -1
@@ -63,7 +63,8 @@ GIT_AUTHOR_NAME='A U Thor'
63 GIT_COMMITTER_EMAIL=committer@example.com
64 GIT_COMMITTER_NAME='C O Mitter'
65 GIT_MERGE_VERBOSITY=5
66 -export GIT_MERGE_VERBOSITY
66 +GIT_MERGE_AUTOEDIT=no
67 +export GIT_MERGE_VERBOSITY GIT_MERGE_AUTOEDIT
68 export GIT_AUTHOR_EMAIL GIT_AUTHOR_NAME
69 export GIT_COMMITTER_EMAIL GIT_COMMITTER_NAME
70 export EDITOR