Merge branch 'jh/optional-path' into jch

Teaches the configuration mechanism that values of type pathname may
be prefixed with ':(optional)' to be treated as such.

* jh/optional-path:
  parseopt: values of pathname type can be prefixed with :(optional)
  config: values of pathname type can be prefixed with :(optional)
  t7500: make each piece more independent

Author: ttaylorr

Documentation/config.txt

@@ -358,7 +358,10 @@ compiled without runtime prefix support, the compiled-in prefix will be
 substituted instead. In the unlikely event that a literal path needs to
 be specified that should _not_ be expanded, it needs to be prefixed by
 `./`, like so: `./%(prefix)/bin`.
-
++
+If prefixed with `:(optional)`, the configuration variable is treated
+as if it does not exist, if the named path does not exist or names an
+empty file.
 
 Variables
 ~~~~~~~~~

config.c

@@ -1364,11 +1364,23 @@ int git_config_string(char **dest, const char *var, const char *value)
 
 int git_config_pathname(char **dest, const char *var, const char *value)
 {
+	int is_optional;
+	char *path;
+
 	if (!value)
 		return config_error_nonbool(var);
-	*dest = interpolate_path(value, 0);
-	if (!*dest)
+
+	is_optional = skip_prefix(value, ":(optional)", &value);
+	path = interpolate_path(value, 0);
+	if (!path)
 		die(_("failed to expand user dir in: '%s'"), value);
+
+	if (is_optional && is_empty_or_missing_file(path)) {
+		free(path);
+		return 0;
+	}
+
+	*dest = path;
 	return 0;
 }
 

parse-options.c

@@ -75,7 +75,6 @@ static enum parse_opt_result do_get_value(struct parse_opt_ctx_t *p,
 {
 	const char *s, *arg;
 	const int unset = flags & OPT_UNSET;
-	int err;
 
 	if (unset && p->opt)
 		return error(_("%s takes no value"), optname(opt, flags));
@@ -131,21 +130,31 @@ static enum parse_opt_result do_get_value(struct parse_opt_ctx_t *p,
 	case OPTION_FILENAME:
 	{
 		const char *value;
-
-		FREE_AND_NULL(*(char **)opt->value);
-
-		err = 0;
+		int is_optional;
 
 		if (unset)
 			value = NULL;
 		else if (opt->flags & PARSE_OPT_OPTARG && !p->opt)
-			value = (const char *) opt->defval;
-		else
-			err = get_arg(p, opt, flags, &value);
+			value = (char *)opt->defval;
+		else {
+			int err = get_arg(p, opt, flags, &value);
+			if (err)
+				return err;
+		}
+		if (!value)
+			return 0;
 
-		if (!err)
-			*(char **)opt->value = fix_filename(p->prefix, value);
-		return err;
+		is_optional = skip_prefix(value, ":(optional)", &value);
+		if (!value)
+			is_optional = 0;
+		value = fix_filename(p->prefix, value);
+		if (is_optional && is_empty_or_missing_file(value)) {
+			free((char *)value);
+		} else {
+			FREE_AND_NULL(*(char **)opt->value);
+			*(const char **)opt->value = value;
+		}
+		return 0;
 	}
 	case OPTION_CALLBACK:
 	{

t/t7500-commit-template-squash-signoff.sh

@@ -37,46 +37,65 @@ test_expect_success 'nonexistent template file should return error' '
 	)
 '
 
+test_expect_success 'nonexistent optional template file on command line' '
+	echo changes >> foo &&
+	git add foo &&
+	(
+		GIT_EDITOR="echo hello >\"\$1\"" &&
+		export GIT_EDITOR &&
+		git commit --template ":(optional)$PWD/notexist"
+	)
+'
+
 test_expect_success 'nonexistent template file in config should return error' '
 	test_config commit.template "$PWD"/notexist &&
 	(
 		GIT_EDITOR="echo hello >\"\$1\"" &&
 		export GIT_EDITOR &&
-		test_must_fail git commit
+		test_must_fail git commit --allow-empty
+	)
+'
+
+test_expect_success 'nonexistent optional template file in config' '
+	test_config commit.template ":(optional)$PWD"/notexist &&
+	(
+		GIT_EDITOR="echo hello >\"\$1\"" &&
+		export GIT_EDITOR &&
+		git commit --allow-empty
 	)
 '
 
 # From now on we'll use a template file that exists.
 TEMPLATE="$PWD"/template
 
 test_expect_success 'unedited template should not commit' '
-	echo "template line" > "$TEMPLATE" &&
-	test_must_fail git commit --template "$TEMPLATE"
+	echo "template line" >"$TEMPLATE" &&
+	test_must_fail git commit --allow-empty --template "$TEMPLATE"
 '
 
 test_expect_success 'unedited template with comments should not commit' '
-	echo "# comment in template" >> "$TEMPLATE" &&
-	test_must_fail git commit --template "$TEMPLATE"
+	echo "# comment in template" >>"$TEMPLATE" &&
+	test_must_fail git commit --allow-empty --template "$TEMPLATE"
 '
 
 test_expect_success 'a Signed-off-by line by itself should not commit' '
 	(
 		test_set_editor "$TEST_DIRECTORY"/t7500/add-signed-off &&
-		test_must_fail git commit --template "$TEMPLATE"
+		test_must_fail git commit --allow-empty --template "$TEMPLATE"
 	)
 '
 
 test_expect_success 'adding comments to a template should not commit' '
 	(
 		test_set_editor "$TEST_DIRECTORY"/t7500/add-comments &&
-		test_must_fail git commit --template "$TEMPLATE"
+		test_must_fail git commit --allow-empty --template "$TEMPLATE"
 	)
 '
 
 test_expect_success 'adding real content to a template should commit' '
 	(
 		test_set_editor "$TEST_DIRECTORY"/t7500/add-content &&
-		git commit --template "$TEMPLATE"
+		git commit --allow-empty --template "$TEMPLATE"
 	) &&
 	commit_msg_is "template linecommit message"
 '