Panic on enum syntax error

[volsa]

The compiler panics, when using an equal (=) instead of an assignment (:=) operator in an enum type definition. For example

TYPE State:
(
    Idle := 0,
    Running = 1, // This should be :=
);
END_TYPE

will panic in the pre-processor with the following message

thread 'main' panicked at compiler/plc_ast/src/pre_processor.rs:81:61:
expected assignment
note: run with `RUST_BACKTRACE=1` environment variable to display a backtrace                 

We should catch these as part of a syntax error in the parser.

[BipulLamsal]

can i check this out?

[riederm]

sure. I think the issue is somewhere here:

rusty/src/parser.rs

Lines 1157 to 1176 in 51efb1e

	fn parse_enum_type_definition(
	lexer: &mut ParseSession,
	name: Option<String>,
	) -> Option<(DataTypeDeclaration, Option<AstNode>)> {
	let start = lexer.last_location();
	let elements = parse_any_in_region(lexer, vec![KeywordParensClose], |lexer| {
	// Parse Enum - we expect at least one element
	let elements = parse_expression_list(lexer);
	Some(elements)
	})?;
	let initializer = lexer.try_consume(KeywordAssignment).then(|| parse_expression(lexer));
	Some((
	DataTypeDeclaration::Definition {
	data_type: Box::new(DataType::EnumType { name, elements, numeric_type: DINT_TYPE.to_string() }),
	location: start.span(&lexer.last_location()),
	scope: lexer.scope.clone(),
	},
	initializer,
	))
	}

Line 1164 allows a coma separated list of any expression. I think it should only expect a coma separated list of Identifiers and/or Assignments.