Default initialize function argument, closes #1090

[sookach]

@hsutter @bluetarpmedia
This patches #1090 by allowing defaulting of arguments in a function call by use of '()' (akin to '{}' in C++).

[MaxSagebaum]

Looks good, a regression test would be nice.

[sookach]

Looks good, a regression test would be nice.

Yeah, it passed on my fork
https://github.com/sookach/cppfront/tree/pr/default_arg

but it looks like the tests don't run on their own in this repo?

[gregmarr]

but it looks like the tests don't run on their own in this repo?

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[MaxSagebaum]

Looks good, a regression test would be nice.

Yeah, it passed on my fork
https://github.com/sookach/cppfront/tree/pr/default_arg

but it looks like the tests don't run on their own in this repo?

Ah, what I meant, is that it would be nice if you add a regression test for the new feature. Sorry for the misunderstanding.

[sookach]

Cool, added a regression test. Let me know what you think.

[MaxSagebaum]

Nice, thanks for adding the test. It looks good to me. I just have a minor comment.

[MaxSagebaum]

I thought, that it might be better to add is_inside_call_expr as an argument. But I think from the geeneral design it is not possible. So the state modification is ok. In order to make the more prominent, I would changed it to:

Suggested change

	is_inside_call_expr = true;
	term.expr_list = expression_list(term.op, lexeme::RightParen);
	is_inside_call_expr = false;
	is_inside_call_expr = true; // Flag this expression list parse.
	term.expr_list = expression_list(term.op, lexeme::RightParen);
	is_inside_call_expr = false;

[sookach]

That makes sense. Done.

[hsutter]

Right, it's either use out-of-band state, or wire a parameter through the call chain. Sometimes I do the former, sometimes the latter, depending on the situation.

[hsutter]

Thanks!