[BUG] Introspect derive macro fail

[notV4l]

Describe the bug
Introspect derive macro will fail for a Span/Array if it's last field and doesnt end by comma & have a comment

Not Ok

#[derive(Copy, Drop, Serde, Introspect)]
#[dojo::model]
pub struct MyModel {
    #[key]
    pub id: u32,
    pub array: Span<u32> // comment <-- fail :(
}

Ok

#[derive(Copy, Drop, Serde, Introspect)]
#[dojo::model]
pub struct MyModel {
    #[key]
    pub id: u32,
    pub array: Span<u32>, // comment
}

Additional context
1.4.0

[glihm]

Ah, nice edge case.

@remybar do you think this is something that's solved by the proc macros parsing, or it's still very similar in how the DB is used?

[remybar]

@notV4l @glihm

Nice catch ! Thanks @notV4l 👍

I have to look at this weird bug but I think this is a bug in the Cairo parser crate (the one which builds the AST) so we will have the same issue with proc macros. If it's a bug in the Cairo parser, I will create an issue on the Starkware repo 🤔

[remybar]

Ok, I have the same issue in my small dojo_proc_macro repo and the issue comes from dojo-lang in this function:

dojo/crates/dojo/lang/src/derive_macros/introspect/utils.rs

Lines 42 to 48 in 1345f9c

	pub fn get_array_item_type(ty: &str) -> String {
	if ty.starts_with("Array<") {
	ty.trim().strip_prefix("Array<").unwrap().strip_suffix('>').unwrap().to_string()
	} else {
	ty.trim().strip_prefix("Span<").unwrap().strip_suffix('>').unwrap().to_string()
	}
	}

The strip_suffix(...).unwrap() call crashes because of the comment.
I will fix it in a PR, thanks 👍

[remybar]

Issue reported to Starkware repo: starkware-libs/cairo#7706.
But the proposed PR makes Dojo struct processing more robust by using regex and so is not impacted by comments.