merge: make branch.<name>.mergeoptions correctly override merge.<option>

The parsing of the additional command line parameters supplied to
the branch.<name>.mergeoptions configuration variable was implemented
at the wrong stage.  If any merge-related variable came after we read
branch.<name>.mergeoptions, the earlier value was overwritten.

We should first read all the merge.* configuration, override them by
reading from branch.<name>.mergeoptions and then finally read from
the command line.

This patch should fix it, even though I now strongly suspect that
branch.<name>.mergeoptions that gives a single command line that
needs to be parsed was likely to be an ill-conceived idea to begin
with.  Sigh...

Helped-by: Jonathan Nieder <jrnieder@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

builtin-merge.c

@@ -54,6 +54,7 @@ static size_t use_strategies_nr, use_strategies_alloc;
 static const char **xopts;
 static size_t xopts_nr, xopts_alloc;
 static const char *branch;
+static char *branch_mergeoptions;
 static int verbosity;
 static int allow_rerere_auto;
 
@@ -474,25 +475,33 @@ cleanup:
 	strbuf_release(&bname);
 }
 
-static int git_merge_config(const char *k, const char *v, void *cb)
+static void parse_branch_merge_options(char *bmo)
 {
-	if (branch && !prefixcmp(k, "branch.") &&
-		!prefixcmp(k + 7, branch) &&
-		!strcmp(k + 7 + strlen(branch), ".mergeoptions")) {
 	const char **argv;
 	int argc;
-		char *buf;
 
-		buf = xstrdup(v);
-		argc = split_cmdline(buf, &argv);
+	if (!bmo)
+		return;
+	argc = split_cmdline(bmo, &argv);
 	if (argc < 0)
 		die("Bad branch.%s.mergeoptions string", branch);
 	argv = xrealloc(argv, sizeof(*argv) * (argc + 2));
 	memmove(argv + 1, argv, sizeof(*argv) * (argc + 1));
 	argc++;
+	argv[0] = "branch.*.mergeoptions";
 	parse_options(argc, argv, NULL, builtin_merge_options,
 		      builtin_merge_usage, 0);
-		free(buf);
+	free(argv);
+}
+
+static int git_merge_config(const char *k, const char *v, void *cb)
+{
+	if (branch && !prefixcmp(k, "branch.") &&
+		!prefixcmp(k + 7, branch) &&
+		!strcmp(k + 7 + strlen(branch), ".mergeoptions")) {
+		free(branch_mergeoptions);
+		branch_mergeoptions = xstrdup(v);
+		return 0;
 	}
 
 	if (!strcmp(k, "merge.diffstat") || !strcmp(k, "merge.stat"))
@@ -918,6 +927,8 @@ int cmd_merge(int argc, const char **argv, const char *prefix)
 	if (diff_use_color_default == -1)
 		diff_use_color_default = git_use_color_default;
 
+	if (branch_mergeoptions)
+		parse_branch_merge_options(branch_mergeoptions);
 	argc = parse_options(argc, argv, prefix, builtin_merge_options,
 			builtin_merge_usage, 0);
 	if (verbosity < 0)

t/t7600-merge.sh

@@ -372,6 +372,38 @@ test_expect_success 'merge c1 with c2 (no-commit in config)' '
 
 test_debug 'gitk --all'
 
+test_expect_success 'merge c1 with c2 (log in config)' '
+	git config branch.master.mergeoptions "" &&
+	git reset --hard c1 &&
+	git merge --log c2 &&
+	git show -s --pretty=tformat:%s%n%b >expect &&
+
+	git config branch.master.mergeoptions --log &&
+	git reset --hard c1 &&
+	git merge c2 &&
+	git show -s --pretty=tformat:%s%n%b >actual &&
+
+	test_cmp expect actual
+'
+
+test_expect_success 'merge c1 with c2 (log in config gets overridden)' '
+	(
+		git config --remove-section branch.master
+		git config --remove-section merge
+	)
+	git reset --hard c1 &&
+	git merge c2 &&
+	git show -s --pretty=tformat:%s%n%b >expect &&
+
+	git config branch.master.mergeoptions "--no-log" &&
+	git config merge.log true &&
+	git reset --hard c1 &&
+	git merge c2 &&
+	git show -s --pretty=tformat:%s%n%b >actual &&
+
+	test_cmp expect actual
+'
+
 test_expect_success 'merge c1 with c2 (squash in config)' '
 	git reset --hard c1 &&
 	git config branch.master.mergeoptions "--squash" &&