fix(config_parser): Gracefully handle BOM (#2166)

* fix(config_parser): Gracefully handle BOM

* Move check to parse_line function

And clarify the error message

Closes #2075

src/components/config_parser.cpp

@@ -1,8 +1,8 @@
+#include "components/config_parser.hpp"
+
 #include <algorithm>
 #include <fstream>
 
-#include "components/config_parser.hpp"
-
 POLYBAR_NS
 
 config_parser::config_parser(const logger& logger, string&& file, string&& bar)
@@ -151,6 +151,11 @@ void config_parser::parse_file(const string& file, file_list path) {
 }
 
 line_t config_parser::parse_line(const string& line) {
+  if (string_util::contains(line, "\ufeff")) {
+    throw syntax_error(
+        "This config file uses UTF-8 with BOM, which is not supported. Please use plain UTF-8 without BOM.");
+  }
+
   string line_trimmed = string_util::trim(line, isspace);
   line_type type = get_line_type(line_trimmed);
 
@@ -193,12 +198,13 @@ line_type config_parser::get_line_type(const string& line) {
     case '#':
       return line_type::COMMENT;
 
-    default:
+    default: {
       if (string_util::contains(line, "=")) {
         return line_type::KEY;
       } else {
         return line_type::UNKNOWN;
       }
+    }
   }
 }
 

tests/unit_tests/components/config_parser.cpp

@@ -1,4 +1,5 @@
 #include "components/config_parser.hpp"
+
 #include "common/test.hpp"
 #include "components/logger.hpp"
 
@@ -98,6 +99,7 @@ TEST_P(ParseLineKeyTest, correctness) {
 
 TEST_F(ParseLineInValidTest, throwsSyntaxError) {
   EXPECT_THROW(parser->parse_line("unknown"), syntax_error);
+  EXPECT_THROW(parser->parse_line("\ufeff"), syntax_error);
 }
 // }}}