X-Git-Url: https://git.tokkee.org/?a=blobdiff_plain;f=builtin%2Fmerge.c;h=5126443fdfe1dc5113943dd3099ab8d87d84887e;hb=d387868a7d29621e85e8c5c061d1f50586db74e5;hp=f385b8ac9e759f74b4711bdb93687202c1bc1600;hpb=f3ccea8dd4ba03c8ed1971c317a14c1c34b61705;p=git.git

diff --git a/builtin/merge.c b/builtin/merge.c
index f385b8ac9..5126443fd 100644
--- a/builtin/merge.c
+++ b/builtin/merge.c
@@ -885,11 +885,21 @@ static void abort_commit(const char *err_msg)
 	exit(1);
 }
 
+static const char merge_editor_comment[] =
+N_("Please enter a commit message to explain why this merge is necessary,\n"
+   "especially if it merges an updated upstream into a topic branch.\n"
+   "\n"
+   "Lines starting with '#' will be ignored, and an empty message aborts\n"
+   "the commit.\n");
+
 static void prepare_to_commit(void)
 {
 	struct strbuf msg = STRBUF_INIT;
+	const char *comment = _(merge_editor_comment);
 	strbuf_addbuf(&msg, &merge_msg);
 	strbuf_addch(&msg, '\n');
+	if (0 < option_edit)
+		strbuf_add_lines(&msg, "# ", comment, strlen(comment));
 	write_merge_msg(&msg);
 	run_hook(get_index_file(), "prepare-commit-msg",
 		 git_path("MERGE_MSG"), "merge", NULL, NULL);
@@ -1099,6 +1109,33 @@ static void write_merge_state(void)
 	close(fd);
 }
 
+static int default_edit_option(void)
+{
+	static const char name[] = "GIT_MERGE_AUTOEDIT";
+	const char *e = getenv(name);
+	struct stat st_stdin, st_stdout;
+
+	if (have_message)
+		/* an explicit -m msg without --[no-]edit */
+		return 0;
+
+	if (e) {
+		int v = git_config_maybe_bool(name, e);
+		if (v < 0)
+			die("Bad value '%s' in environment '%s'", e, name);
+		return v;
+	}
+
+	/* Use editor if stdin and stdout are the same and is a tty */
+	return (!fstat(0, &st_stdin) &&
+		!fstat(1, &st_stdout) &&
+		isatty(0) && isatty(1) &&
+		st_stdin.st_dev == st_stdout.st_dev &&
+		st_stdin.st_ino == st_stdout.st_ino &&
+		st_stdin.st_mode == st_stdout.st_mode);
+}
+
+
 int cmd_merge(int argc, const char **argv, const char *prefix)
 {
 	unsigned char result_tree[20];
@@ -1288,7 +1325,7 @@ int cmd_merge(int argc, const char **argv, const char *prefix)
 		    merge_remote_util(commit)->obj &&
 		    merge_remote_util(commit)->obj->type == OBJ_TAG) {
 			if (option_edit < 0)
-				option_edit = 1;
+				option_edit = default_edit_option();
 			allow_fast_forward = 0;
 		}
 	}