Wrong borrowing of expression in template!

[emi2k01]

Describe the bug
Given an expression with multiple rvalues a, b, c, the macro will expand to &a....c instead of &(a....c)

To Reproduce
Steps to reproduce the behavior:

use sycamore::prelude::*;

#[component(App<G>)]
fn app() -> Template<G> {
    template! {
        div {
            (0+1)
        }
    }
}

fn main() {
    sycamore::render(|| template! { App() });
}

The macro will expand 0+1 to IntoTemplate::create(&0+1) instead of IntoTemplate::create(&(0+1)).

Replacing 0+1 with (0+1) so that the end result looks like ((0+1)) makes it work.

Expected behavior
Borrow the whole expression. Not only the first rvalue.

I think the macro should always wrap the expansion of the inner expression in parenthesis.

Environment

• Sycamore: master

[emi2k01]

I forgot to write an update on this issue.

After I submitted the issue, I planned to write a MR but, while reading the sycamore-macro, I found a lot of code that used &__el or similar. This can be found in the code for the attributes parser, the element parser, and probably other parts of the code.

I don't know if all instances of this should be wrapped in parenthesis.

Look at this:

> grep "(&__el|&#)" -ER packages/sycamore-macro/
packages/sycamore-macro/src/template/mod.rs:                    ::sycamore::template::IntoTemplate::create(&#splice)
packages/sycamore-macro/src/template/element.rs:                        ::sycamore::generic_node::GenericNode::append_child(&__el, &#element);
packages/sycamore-macro/src/template/element.rs:                            &__el,
packages/sycamore-macro/src/template/element.rs:                                &__el,
packages/sycamore-macro/src/template/element.rs:                                ::sycamore::template::IntoTemplate::create(&#splice),
packages/sycamore-macro/src/template/element.rs:                                ::sycamore::generic_node::GenericNode::append_child(&__el, &__marker);
packages/sycamore-macro/src/template/element.rs:                                ::sycamore::generic_node::GenericNode::append_child(&__el, &__marker);
packages/sycamore-macro/src/template/element.rs:                                ::sycamore::generic_node::GenericNode::append_child(&__el, &__marker);
packages/sycamore-macro/src/template/element.rs:                                    &__el,
packages/sycamore-macro/src/template/element.rs:                                   &__el,
packages/sycamore-macro/src/template/element.rs:                                       ::sycamore::template::IntoTemplate::create(&#splice)
packages/sycamore-macro/src/template/attributes.rs:                        &::std::string::ToString::to_string(&#expr)
packages/sycamore-macro/src/template/attributes.rs:                        ::sycamore::generic_node::GenericNode::set_class_name(&__el, #quoted_text);
packages/sycamore-macro/src/template/attributes.rs:                            &__el,
packages/sycamore-macro/src/template/attributes.rs:                            let __el = ::std::clone::Clone::clone(&__el);
packages/sycamore-macro/src/template/attributes.rs:                        ::sycamore::generic_node::GenericNode::set_attribute(&__el, #name, "");
packages/sycamore-macro/src/template/attributes.rs:                        ::sycamore::generic_node::GenericNode::remove_attribute(&__el, #name);
packages/sycamore-macro/src/template/attributes.rs:                            let __el = ::std::clone::Clone::clone(&__el);
packages/sycamore-macro/src/template/attributes.rs:                            let __el = ::std::clone::Clone::clone(&__el);
packages/sycamore-macro/src/template/attributes.rs:                                    &__el,
packages/sycamore-macro/src/template/attributes.rs:                            &__el,
packages/sycamore-macro/src/template/attributes.rs:                        &__el,
packages/sycamore-macro/src/template/attributes.rs:                        ::sycamore::rt::JsValue::as_bool(&#event_target_prop).unwrap()
packages/sycamore-macro/src/template/attributes.rs:                        ::sycamore::rt::JsValue::as_string(&#event_target_prop).unwrap()
packages/sycamore-macro/src/template/attributes.rs:                        let __el = ::std::clone::Clone::clone(&__el);
packages/sycamore-macro/src/template/attributes.rs:                                &__el,
packages/sycamore-macro/src/template/attributes.rs:                                &#convert_into_jsvalue_fn,
packages/sycamore-macro/src/template/attributes.rs:                        &__el,
packages/sycamore-macro/src/template/attributes.rs:                        &#expr,
packages/sycamore-macro/src/template/attributes.rs:                        ::std::clone::Clone::clone(&__el),

I don't know if there are more of these.

[lukechu10]

These don't need to be parenthesized because it references a variable. &__el is expanded into &__el so there can be no ambiguities about that there. The only place that needs to be changed is when an expression is expanded so when there is something like &#expr which should become something like &(#expr). In fact, I am somewhat surprised that quote! doesn't automatically handle this.