How to fully ignore whitespace

[DecrepitHuman]

My grammar does not rely on whitespace, and from the book I am unable to understand how handling whitespace works.
From what I see I think rule ~ rule automatically matches whitespace, however I'm getting errors when working from that assumption. The problem:

decl = _{ "struct" ~ ident ~ "{" ~ "}" }

Does not match:

struct String {}

It produces the following error:

Err(Error { variant: ParsingError { positives: [ident], negatives: [] }, location: Pos(6), line_col: Pos((1, 7)), path: None, line: "struct String {}", continued_line: None })

I have no need for whitespace, it can simply be ignored. Anybody able to help me out with this?

[CAD97]

You want to define what your grammar's implicit whitespace is. e.g.

WHITESPACE = _{ " " | NEWLINE }

[DecrepitHuman]

I've even tried this but with "\n" instead of NEWLINE, my mistake then.
I appreciate the fast response. Thank you