better error reporting

Makefile

@@ -2,8 +2,8 @@ MAKEFLAGS="-j $(grep -c ^processor /proc/cpuinfo)"
 CXXFLAGS=-std=c++20 -Wall -Wextra -O2 -Werror=switch
 CPPFLAGS=-Ilib/expected/ -Ilib/ut/ -Isrc/
 
-Obj=bin/lexer.o \
-		bin/errors.o \
+Obj=bin/errors.o \
+		bin/lexer.o \
 		bin/unicode.o
 
 all: bin/musique bin/unit-tests

src/errors.cc

@@ -20,9 +20,30 @@ std::ostream& operator<<(std::ostream& os, Error const& err)
 		return os << "end of file\n";
 
 	case errors::Unrecognized_Character:
-		return os << "unrecognized charater 0x" << std::hex << err.invalid_character
-			<< "(char: '" << utf8::Print(err.invalid_character) << "')\n";
+		if (err.invalid_character) {
+			return os << "unrecognized charater U+" << std::hex << err.invalid_character
+				<< " (char: '" << utf8::Print{err.invalid_character} << "')\n";
+		} else {
+			return os << "unrecognized character\n";
+		}
 	}
 
 	return os << "unrecognized error type\n";
 }
+
+Error errors::unrecognized_character(u32 invalid_character)
+{
+	Error err;
+	err.type = errors::Unrecognized_Character;
+	err.invalid_character = invalid_character;
+	return err;
+}
+
+Error errors::unrecognized_character(u32 invalid_character, Location location)
+{
+	Error err;
+	err.type = errors::Unrecognized_Character;
+	err.invalid_character = invalid_character;
+	err.location = std::move(location);
+	return err;
+}

src/lexer.cc

@@ -40,7 +40,7 @@ auto Lexer::next_token() -> Result<Token>
 		return { Token::Type::Numeric, finish(), token_location };
 	}
 
-	return errors::Unrecognized_Character;
+	return errors::unrecognized_character(peek(), token_location);
 }
 
 auto Lexer::peek() const -> u32

src/main.cc

@@ -9,6 +9,7 @@ std::string_view Source = R"musique(
 tl::expected<void, Error> Main()
 {
 	Lexer lexer{Source};
+	lexer.location.filename = "example.mq";
 
 	for (;;) {
 		auto token = Try(lexer.next_token());
@@ -20,7 +21,7 @@ int main()
 {
 	auto result = Main();
 	if (not result.has_value()) {
-		std::cerr << result.error() << std::endl;
+		std::cerr << result.error() << std::flush;
 		return 1;
 	}
 }

src/musique.hh

@@ -61,18 +61,33 @@ struct Error
 	bool operator==(errors::Type);
 };
 
+namespace errors
+{
+	Error unrecognized_character(u32 invalid_character);
+	Error unrecognized_character(u32 invalid_character, Location location);
+}
+
+
 template<typename T>
 struct Result : tl::expected<T, Error>
 {
+	using Storage = tl::expected<T, Error>;
+
 	constexpr Result() = default;
 
-	constexpr Result(errors::Type error) : tl::expected<T, Error>(tl::unexpected(Error { error }))
+	constexpr Result(errors::Type error)
+		: Storage(tl::unexpected(Error { error }))
+	{
+	}
+
+	constexpr Result(Error error)
+		: Storage(tl::unexpected(std::move(error)))
 	{
 	}
 
 	template<typename ...Args>
 	constexpr Result(Args&& ...args)
-		: tl::expected<T, Error>( T{ std::forward<Args>(args)... } )
+		: Storage( T{ std::forward<Args>(args)... } )
 	{
 	}
 };