toml: fix scanning of short unicode escapes (#12491)

Author: larpon

vlib/toml/scanner/scanner.v

@@ -516,7 +516,7 @@ fn (mut s Scanner) handle_escapes(quote byte, is_multiline bool) (string, int) {
 			&& byte(s.peek(4)).is_hex_digit() && byte(s.peek(5)).is_hex_digit() {
 			lit += s.text[s.pos + 1..s.pos + 6] //.ascii_str()
 			util.printdbg(@MOD + '.' + @STRUCT + '.' + @FN, 'gulp escaped unicode `$lit`')
-			return lit, 4
+			return lit, 5
 		} else if s.peek(1) == quote {
 			if (!is_multiline && s.peek(2) == `\n`)
 				|| (is_multiline && s.peek(2) == quote && s.peek(3) == quote && s.peek(4) == `\n`) {

vlib/toml/tests/strings_test.v

@@ -28,6 +28,8 @@ two
 three
 four
 '''"
+	toml_unicode_escapes = r'short = "\u03B4"
+long = "\U000003B4"'
 )
 
 fn test_multiline_strings() {
@@ -66,6 +68,15 @@ fn test_multiline_strings() {
 	assert value.string() == 'aaa' + '"""' + 'bbb'
 }
 
+fn test_unicode_escapes() {
+	mut toml_doc := toml.parse(toml_unicode_escapes) or { panic(err) }
+
+	mut value := toml_doc.value('short')
+	assert value.string() == r'\u03B4'
+	value = toml_doc.value('long')
+	assert value.string() == r'\U000003B4'
+}
+
 fn test_literal_strings() {
 	toml_file :=
 		os.real_path(os.join_path(os.dir(@FILE), 'testdata', os.file_name(@FILE).all_before_last('.'))) +