We're getting more places where we specify what's allowed: allow_selfq, allow_eof, allow_void. Since we already pass the parser everywhere, I wonder if we should add these options as context rather than passing them individually to each method:

parser.context.allow_void

@Morriar I'd like to keep allow_void (and allow_selfq) as dedicated parameter. They are not part of the parser’s global state, but rather values that change frequently during parsing. So I don’t think it’s reasonable to write code that preserves and restores the context, like:

parser_context old_context = parser.context;
parser.context.allow_void = true;

parse_type(parser);

parser.context = old_context;

I’m planning to introduce two more flags for parsing self and class/instance types (#2336). These flags are static during parsing, so I agree that making them attributes of the parser makes sense.

These flags are static during parsing

Oops — they are constant while parsing a type, but they can change when parsing an entire signature.