Error reporting when too many closing parens at the end

include/musique.hh

@@ -176,6 +176,14 @@ namespace errors
 		size_t size;
 	};
 
+	struct Closing_Token_Without_Opening
+	{
+		enum {
+			Block = ']',
+			Paren = ')'
+		} type;
+	};
+
 	/// Collection of messages that are considered internal and should not be printed to the end user.
 	namespace internal
 	{
@@ -195,6 +203,7 @@ namespace errors
 
 	/// All possible error types
 	using Details = std::variant<
+		Closing_Token_Without_Opening,
 		Expected_Expression_Separator_Before,
 		Failed_Numeric_Parsing,
 		Literal_As_Identifier,

src/errors.cc

@@ -146,6 +146,11 @@ std::ostream& operator<<(std::ostream& os, Error const& err)
 		[](errors::Expected_Expression_Separator_Before const&) { return "Missing semicolon"; },
 		[](errors::Literal_As_Identifier const&)                { return "Literal used in place of an identifier"; },
 		[](errors::Out_Of_Range const&)                         { return "Index out of range"; },
+		[](errors::Closing_Token_Without_Opening const& err)    {
+			return err.type == errors::Closing_Token_Without_Opening::Block
+				? "Block closing without opening"
+				: "Closing parentheses without opening";
+		},
 		[](errors::Unsupported_Types_For const& type)           {
 			return type.type == errors::Unsupported_Types_For::Function
 				? "Function called with wrong arguments"
@@ -352,6 +357,17 @@ std::ostream& operator<<(std::ostream& os, Error const& err)
 			print_error_line(loc);
 		},
 
+		[&](errors::Closing_Token_Without_Opening const& err) {
+			if (err.type ==	errors::Closing_Token_Without_Opening::Block) {
+				os << "Found strange block closing ']' without previous block opening '['\n";
+			} else {
+				os << "Found strange closing ')' without previous '('\n";
+			}
+
+			os << '\n';
+			print_error_line(loc);
+		},
+
 		[&](errors::Unexpected_Keyword const&)               { unimplemented(); },
 	}, err.details);
 
@@ -367,5 +383,7 @@ void errors::all_tokens_were_not_parsed(std::span<Token> tokens)
 		std::cerr << token << '\n';
 	}
 
+	encourage_contact(std::cerr);
+
 	std::exit(1);
 }

src/parser.cc

@@ -70,6 +70,19 @@ Result<Ast> Parser::parse(std::string_view source, std::string_view filename, un
 				.location = parser.peek()->location
 			};
 		}
+
+		if (parser.expect(Token::Type::Close_Paren) || parser.expect(Token::Type::Close_Block)) {
+			auto const tok = parser.consume();
+			return Error {
+				.details = errors::Closing_Token_Without_Opening {
+					.type = tok.type == Token::Type::Close_Paren
+						? errors::Closing_Token_Without_Opening::Paren
+						: errors::Closing_Token_Without_Opening::Block
+				},
+				.location = tok.location
+			};
+		}
+
 		errors::all_tokens_were_not_parsed(std::span(parser.tokens).subspan(parser.token_id));
 	}