From bae0141f981b7ffe5abf79c5f2310463894f593e Mon Sep 17 00:00:00 2001
From: Tim Kurdov <tim.kurdov@gmail.com>
Date: Sat, 28 Oct 2023 16:36:56 +0100
Subject: [PATCH] Remove deprecated `class=(...)` syntax (#3497)

* removed class=(...) syntax

* made DynamicName::expr a group instead of a block

* fixed tests, silenced all unused_must_use warnings

* fixed wasm test
---
 .../yew-macro/src/html_tree/html_element.rs   | 66 ++++-----------
 packages/yew-macro/src/props/element.rs       | 20 +----
 .../yew-macro/tests/html_macro/block-pass.rs  | 16 ++--
 .../html_macro/component-any-children-pass.rs | 28 +++----
 .../tests/html_macro/component-pass.rs        | 34 ++++----
 .../tests/html_macro/dyn-element-pass.rs      |  7 +-
 .../tests/html_macro/element-fail.rs          |  4 -
 .../tests/html_macro/element-fail.stderr      | 84 ++++++-------------
 .../html_macro/generic-component-pass.rs      | 28 +++----
 .../tests/html_macro/html-element-pass.rs     | 15 ++--
 .../tests/html_macro/html-if-pass.rs          | 48 +++++------
 .../tests/html_macro/html-node-pass.rs        | 26 +++---
 .../tests/html_macro/iterable-pass.rs         | 12 +--
 .../yew-macro/tests/html_macro/list-pass.rs   | 10 +--
 .../yew-macro/tests/html_macro/node-pass.rs   | 30 +++----
 .../yew-macro/tests/html_macro/svg-pass.rs    |  4 +-
 packages/yew/src/dom_bundle/btag/mod.rs       |  4 +-
 17 files changed, 172 insertions(+), 264 deletions(-)

diff --git a/packages/yew-macro/src/html_tree/html_element.rs b/packages/yew-macro/src/html_tree/html_element.rs
index a501644941b..83a4faf0059 100644
--- a/packages/yew-macro/src/html_tree/html_element.rs
+++ b/packages/yew-macro/src/html_tree/html_element.rs
@@ -1,13 +1,13 @@
-use proc_macro2::{Delimiter, Span, TokenStream};
+use proc_macro2::{Delimiter, Group, Span, TokenStream};
 use proc_macro_error::emit_warning;
 use quote::{quote, quote_spanned, ToTokens};
 use syn::buffer::Cursor;
 use syn::parse::{Parse, ParseStream};
 use syn::spanned::Spanned;
-use syn::{Block, Expr, Ident, Lit, LitStr, Token};
+use syn::{Expr, Ident, Lit, LitStr, Token};
 
 use super::{HtmlChildrenTree, HtmlDashedName, TagTokens};
-use crate::props::{ClassesForm, ElementProps, Prop, PropDirective};
+use crate::props::{ElementProps, Prop, PropDirective};
 use crate::stringify::{Stringify, Value};
 use crate::{is_ide_completion, non_capitalized_ascii, Peek, PeekValue};
 
@@ -190,39 +190,11 @@ impl ToTokens for HtmlElement {
                     ))
                 },
             );
-            let class_attr = classes.as_ref().and_then(|classes| match classes {
-                ClassesForm::Tuple(classes) => {
-                    let span = classes.span();
-                    let classes: Vec<_> = classes.elems.iter().collect();
-                    let n = classes.len();
-
-                    let deprecation_warning = quote_spanned! {span=>
-                        #[deprecated(
-                            note = "the use of `(...)` with the attribute `class` is deprecated and will be removed in version 0.19. Use the `classes!` macro instead."
-                        )]
-                        fn deprecated_use_of_class() {}
-
-                        if false {
-                            deprecated_use_of_class();
-                        };
-                    };
 
-                    Some((
-                        LitStr::new("class", span),
-                        Value::Dynamic(quote! {
-                            {
-                                #deprecation_warning
-
-                                let mut __yew_classes = ::yew::html::Classes::with_capacity(#n);
-                                #(__yew_classes.push(#classes);)*
-                                __yew_classes
-                            }
-                        }),
-                        None,
-                    ))
-                }
-                ClassesForm::Single(classes) => {
-                    match classes.try_into_lit() {
+            let class_attr =
+                classes
+                    .as_ref()
+                    .and_then(|classes| match classes.value.try_into_lit() {
                         Some(lit) => {
                             if lit.value().is_empty() {
                                 None
@@ -235,17 +207,16 @@ impl ToTokens for HtmlElement {
                             }
                         }
                         None => {
+                            let expr = &classes.value;
                             Some((
-                                LitStr::new("class", classes.span()),
+                                LitStr::new("class", classes.label.span()),
                                 Value::Dynamic(quote! {
-                                    ::std::convert::Into::<::yew::html::Classes>::into(#classes)
+                                    ::std::convert::Into::<::yew::html::Classes>::into(#expr)
                                 }),
                                 None,
                             ))
                         }
-                    }
-                }
-            });
+                    });
 
             fn apply_as(directive: Option<&PropDirective>) -> TokenStream {
                 match directive {
@@ -383,7 +354,7 @@ impl ToTokens for HtmlElement {
             }
             TagName::Expr(name) => {
                 let vtag = Ident::new("__yew_vtag", name.span());
-                let expr = &name.expr;
+                let expr = name.expr.as_ref().map(Group::stream);
                 let vtag_name = Ident::new("__yew_vtag_name", expr.span());
 
                 let void_children = Ident::new("__yew_void_children", Span::mixed_site());
@@ -411,10 +382,6 @@ impl ToTokens for HtmlElement {
                 // this way we get a nice error message (with the correct span) when the expression
                 // doesn't return a valid value
                 quote_spanned! {expr.span()=> {
-                    #[allow(unused_braces)]
-                    // e.g. html!{<@{"div"}/>} will set `#expr` to `{"div"}`
-                    // (note the extra braces). Hence the need for the `allow`.
-                    // Anyways to remove the braces?
                     let mut #vtag_name = ::std::convert::Into::<
                         ::yew::virtual_dom::AttrValue
                     >::into(#expr);
@@ -500,7 +467,7 @@ fn wrap_attr_value<T: ToTokens>(value: T) -> TokenStream {
 
 pub struct DynamicName {
     at: Token![@],
-    expr: Option<Block>,
+    expr: Option<Group>,
 }
 
 impl Peek<'_, ()> for DynamicName {
@@ -524,12 +491,7 @@ impl Parse for DynamicName {
     fn parse(input: ParseStream) -> syn::Result<Self> {
         let at = input.parse()?;
         // the expression block is optional, closing tags don't have it.
-        let expr = if input.cursor().group(Delimiter::Brace).is_some() {
-            Some(input.parse()?)
-        } else {
-            None
-        };
-
+        let expr = input.parse().ok();
         Ok(Self { at, expr })
     }
 }
diff --git a/packages/yew-macro/src/props/element.rs b/packages/yew-macro/src/props/element.rs
index cd50b71b692..17a90e3f9db 100644
--- a/packages/yew-macro/src/props/element.rs
+++ b/packages/yew-macro/src/props/element.rs
@@ -2,27 +2,13 @@ use std::collections::HashSet;
 
 use once_cell::sync::Lazy;
 use syn::parse::{Parse, ParseStream};
-use syn::{Expr, ExprTuple};
 
 use super::{Prop, Props, SpecialProps};
 
-pub enum ClassesForm {
-    Tuple(ExprTuple),
-    Single(Box<Expr>),
-}
-impl ClassesForm {
-    fn from_expr(expr: Expr) -> Self {
-        match expr {
-            Expr::Tuple(expr_tuple) => ClassesForm::Tuple(expr_tuple),
-            expr => ClassesForm::Single(Box::new(expr)),
-        }
-    }
-}
-
 pub struct ElementProps {
     pub attributes: Vec<Prop>,
     pub listeners: Vec<Prop>,
-    pub classes: Option<ClassesForm>,
+    pub classes: Option<Prop>,
     pub booleans: Vec<Prop>,
     pub value: Option<Prop>,
     pub checked: Option<Prop>,
@@ -42,9 +28,7 @@ impl Parse for ElementProps {
         let booleans =
             props.drain_filter(|prop| BOOLEAN_SET.contains(prop.label.to_string().as_str()));
 
-        let classes = props
-            .pop("class")
-            .map(|prop| ClassesForm::from_expr(prop.value));
+        let classes = props.pop("class");
         let value = props.pop("value");
         let checked = props.pop("checked");
         let special = props.special;
diff --git a/packages/yew-macro/tests/html_macro/block-pass.rs b/packages/yew-macro/tests/html_macro/block-pass.rs
index d8f527e6e46..6a5bd15c632 100644
--- a/packages/yew-macro/tests/html_macro/block-pass.rs
+++ b/packages/yew-macro/tests/html_macro/block-pass.rs
@@ -37,27 +37,27 @@ pub struct u8;
 pub struct usize;
 
 fn main() {
-    ::yew::html! { <>{ "Hi" }</> };
-    ::yew::html! { <>{ ::std::format!("Hello") }</> };
-    ::yew::html! { <>{ ::std::string::ToString::to_string("Hello") }</> };
+    _ = ::yew::html! { <>{ "Hi" }</> };
+    _ = ::yew::html! { <>{ ::std::format!("Hello") }</> };
+    _ = ::yew::html! { <>{ ::std::string::ToString::to_string("Hello") }</> };
 
     let msg = "Hello";
-    ::yew::html! { <div>{ msg }</div> };
+    _ = ::yew::html! { <div>{ msg }</div> };
 
     let subview = ::yew::html! { "subview!" };
-    ::yew::html! { <div>{ subview }</div> };
+    _ = ::yew::html! { <div>{ subview }</div> };
 
     let subview = || ::yew::html! { "subview!" };
-    ::yew::html! { <div>{ subview() }</div> };
+    _ = ::yew::html! { <div>{ subview() }</div> };
 
-    ::yew::html! {
+    _ = ::yew::html! {
         <ul>
             { for ::std::iter::Iterator::map(0..3, |num| { ::yew::html! { <span>{ num }</span> }}) }
         </ul>
     };
 
     let item = |num| ::yew::html! { <li>{ ::std::format!("item {}!", num) }</li> };
-    ::yew::html! {
+    _ = ::yew::html! {
         <ul>
             { for ::std::iter::Iterator::map(0..3, item) }
         </ul>
diff --git a/packages/yew-macro/tests/html_macro/component-any-children-pass.rs b/packages/yew-macro/tests/html_macro/component-any-children-pass.rs
index c9b9e0f1777..d7b1ab3cb8e 100644
--- a/packages/yew-macro/tests/html_macro/component-any-children-pass.rs
+++ b/packages/yew-macro/tests/html_macro/component-any-children-pass.rs
@@ -159,10 +159,10 @@ pub fn RenderPropComp(_props: &RenderPropProps) -> ::yew::Html {
 }
 
 fn compile_pass() {
-    ::yew::html! { <Child int=1 /> };
-    ::yew::html! { <Child int=1 r#fn=1 /> };
+    _ = ::yew::html! { <Child int=1 /> };
+    _ = ::yew::html! { <Child int=1 r#fn=1 /> };
 
-    ::yew::html! {
+    _ = ::yew::html! {
         <>
             <Child int=1 />
             <scoped::Child int=1 />
@@ -171,7 +171,7 @@ fn compile_pass() {
 
     let props = <<Child as ::yew::Component>::Properties as ::std::default::Default>::default();
     let node_ref = <::yew::NodeRef as ::std::default::Default>::default();
-    ::yew::html! {
+    _ = ::yew::html! {
         <>
             <Child ..::std::clone::Clone::clone(&props) />
             <Child int={1} ..props />
@@ -183,7 +183,7 @@ fn compile_pass() {
         </>
     };
 
-    ::yew::html! {
+    _ = ::yew::html! {
         <>
             <Child int=1 string="child" />
             <Child int=1 />
@@ -199,17 +199,17 @@ fn compile_pass() {
     };
 
     let name_expr = "child";
-    ::yew::html! {
+    _ = ::yew::html! {
         <Child int=1 string={name_expr} />
     };
 
     let string = "child";
     let int = 1;
-    ::yew::html! {
+    _ = ::yew::html! {
         <Child {int} {string} />
     };
 
-    ::yew::html! {
+    _ = ::yew::html! {
         <>
             <Child int=1 />
             <Child int=1 optional_callback={::std::option::Option::Some(<::yew::Callback<()> as ::std::convert::From<_>>::from(|_| ()))} />
@@ -219,7 +219,7 @@ fn compile_pass() {
     };
 
     let node_ref = <::yew::NodeRef as ::std::default::Default>::default();
-    ::yew::html! {
+    _ = ::yew::html! {
         <>
             <Child int=1 r#ref={node_ref} />
         </>
@@ -227,7 +227,7 @@ fn compile_pass() {
 
     let int = 1;
     let node_ref = <::yew::NodeRef as ::std::default::Default>::default();
-    ::yew::html! {
+    _ = ::yew::html! {
         <>
             <Child {int} r#ref={node_ref} />
         </>
@@ -236,7 +236,7 @@ fn compile_pass() {
     let props = <<Container as ::yew::Component>::Properties as ::std::default::Default>::default();
     let child_props =
         <<Child as ::yew::Component>::Properties as ::std::default::Default>::default();
-    ::yew::html! {
+    _ = ::yew::html! {
         <>
             <Container int=1 />
             <Container int=1></Container>
@@ -292,7 +292,7 @@ fn compile_pass() {
         ]
     };
 
-    ::yew::html! {
+    _ = ::yew::html! {
         <>
             {
                 ::std::iter::Iterator::collect::<::yew::virtual_dom::VNode>(
@@ -321,9 +321,9 @@ fn compile_pass() {
         </>
     };
 
-    ::yew::html_nested! { 1 };
+    _ = ::yew::html_nested! { 1 };
 
-    ::yew::html! {
+    _ = ::yew::html! {
         <RenderPropComp>
             {|_arg| {}}
         </RenderPropComp>
diff --git a/packages/yew-macro/tests/html_macro/component-pass.rs b/packages/yew-macro/tests/html_macro/component-pass.rs
index f971f66c4cb..5cc59c4208d 100644
--- a/packages/yew-macro/tests/html_macro/component-pass.rs
+++ b/packages/yew-macro/tests/html_macro/component-pass.rs
@@ -167,10 +167,10 @@ mod scoped {
 }
 
 fn compile_pass() {
-    ::yew::html! { <Child int=1 /> };
-    ::yew::html! { <Child int=1 r#fn=1 /> };
+    _ = ::yew::html! { <Child int=1 /> };
+    _ = ::yew::html! { <Child int=1 r#fn=1 /> };
 
-    ::yew::html! {
+    _ = ::yew::html! {
         <>
             <Child int=1 />
             <scoped::Child int=1 />
@@ -179,7 +179,7 @@ fn compile_pass() {
 
     let props = <<Child as ::yew::Component>::Properties as ::std::default::Default>::default();
     let node_ref = <::yew::NodeRef as ::std::default::Default>::default();
-    ::yew::html! {
+    _ = ::yew::html! {
         <>
             <Child ..::std::clone::Clone::clone(&props) />
             <Child int={1} ..props />
@@ -191,7 +191,7 @@ fn compile_pass() {
         </>
     };
 
-    ::yew::html! {
+    _ = ::yew::html! {
         <>
             <Child int=1 string="child" />
             <Child int=1 />
@@ -207,17 +207,17 @@ fn compile_pass() {
     };
 
     let name_expr = "child";
-    ::yew::html! {
+    _ = ::yew::html! {
         <Child int=1 string={name_expr} />
     };
 
     let string = "child";
     let int = 1;
-    ::yew::html! {
+    _ = ::yew::html! {
         <Child {int} {string} />
     };
 
-    ::yew::html! {
+    _ = ::yew::html! {
         <>
             <Child int=1 />
             <Child int=1 optional_callback={::std::option::Option::Some(<::yew::Callback<()> as ::std::convert::From<_>>::from(|_| ()))} />
@@ -227,7 +227,7 @@ fn compile_pass() {
     };
 
     let node_ref = <::yew::NodeRef as ::std::default::Default>::default();
-    ::yew::html! {
+    _ = ::yew::html! {
         <>
             <Child int=1 r#ref={node_ref} />
         </>
@@ -235,7 +235,7 @@ fn compile_pass() {
 
     let int = 1;
     let node_ref = <::yew::NodeRef as ::std::default::Default>::default();
-    ::yew::html! {
+    _ = ::yew::html! {
         <>
             <Child {int} r#ref={node_ref} />
         </>
@@ -244,7 +244,7 @@ fn compile_pass() {
     let props = <<Container as ::yew::Component>::Properties as ::std::default::Default>::default();
     let child_props =
         <<Child as ::yew::Component>::Properties as ::std::default::Default>::default();
-    ::yew::html! {
+    _ = ::yew::html! {
         <>
             <Container int=1 />
             <Container int=1></Container>
@@ -287,7 +287,7 @@ fn compile_pass() {
         </>
     };
 
-    ::yew::html! {
+    _ = ::yew::html! {
         <>
             <ChildContainer int=1 />
             <ChildContainer int=1></ChildContainer>
@@ -296,7 +296,7 @@ fn compile_pass() {
         </>
     };
 
-    ::yew::html! {
+    _ = ::yew::html! {
         <ChildContainer int=1>
             <AltChild />
             <Child int=1 />
@@ -318,13 +318,13 @@ fn compile_pass() {
         ::yew::html_nested! { <Child int=1 /> },
         ::yew::html_nested! { <Child int=2 /> },
     ];
-    ::yew::html! {
+    _ = ::yew::html! {
         <ChildContainer int=1>
             { ::std::clone::Clone::clone(&children) }
         </ChildContainer>
     };
     // https://github.com/yewstack/yew/issues/1527
-    ::yew::html! {
+    _ = ::yew::html! {
         <ChildContainer int=1>
             { for children }
         </ChildContainer>
@@ -343,7 +343,7 @@ fn compile_pass() {
         ]
     };
 
-    ::yew::html! {
+    _ = ::yew::html! {
         <>
             {
                 ::std::iter::Iterator::collect::<::yew::virtual_dom::VNode>(
@@ -372,7 +372,7 @@ fn compile_pass() {
         </>
     };
 
-    ::yew::html_nested! { 1 };
+    _ = ::yew::html_nested! { 1 };
 }
 
 #[derive(
diff --git a/packages/yew-macro/tests/html_macro/dyn-element-pass.rs b/packages/yew-macro/tests/html_macro/dyn-element-pass.rs
index 27dd094c0f9..0ab298fe342 100644
--- a/packages/yew-macro/tests/html_macro/dyn-element-pass.rs
+++ b/packages/yew-macro/tests/html_macro/dyn-element-pass.rs
@@ -43,17 +43,16 @@ fn main() {
         move || ::std::option::Option::unwrap(::std::iter::Iterator::next(&mut it))
     };
 
-    ::yew::html! {
+    _ = ::yew::html! {
         <@{ dyn_tag() }>
             <@{ next_extra_tag() } class="extra-a"/>
             <@{ next_extra_tag() } class="extra-b"/>
         </@>
     };
 
-    ::yew::html! {
+    _ = ::yew::html! {
         <@{
-            let tag = dyn_tag();
-            if tag == "test" {
+            if dyn_tag() == "test" {
                 "div"
             } else {
                 "a"
diff --git a/packages/yew-macro/tests/html_macro/element-fail.rs b/packages/yew-macro/tests/html_macro/element-fail.rs
index ac8f217e0f1..52f494fc67f 100644
--- a/packages/yew-macro/tests/html_macro/element-fail.rs
+++ b/packages/yew-macro/tests/html_macro/element-fail.rs
@@ -76,11 +76,7 @@ fn compile_fail() {
     // type mismatch
     html! { <@{55}></@> };
 
-    // check for deprecation warning
-    html! { <div class={("deprecated", "warning")} /> };
-
     // Missing curly braces
-    html! { <div class=("deprecated", "warning") /> };
     html! { <input ref=() /> };
     html! { <input ref=() ref=() /> };
     html! { <input onfocus=Some(5) /> };
diff --git a/packages/yew-macro/tests/html_macro/element-fail.stderr b/packages/yew-macro/tests/html_macro/element-fail.stderr
index 9a413f6ef4e..11f9e7d631a 100644
--- a/packages/yew-macro/tests/html_macro/element-fail.stderr
+++ b/packages/yew-macro/tests/html_macro/element-fail.stderr
@@ -142,38 +142,14 @@ error: dynamic closing tags must not have a body (hint: replace it with just `</
 75 |     html! { <@{"test"}></@{"test"}> };
    |                           ^^^^^^^^
 
-error: the property value must be either a literal or enclosed in braces. Consider adding braces around your expression.: Expr::Tuple {
-           attrs: [],
-           paren_token: Paren,
-           elems: [
-               Expr::Lit {
-                   attrs: [],
-                   lit: Lit::Str {
-                       token: "deprecated",
-                   },
-               },
-               Comma,
-               Expr::Lit {
-                   attrs: [],
-                   lit: Lit::Str {
-                       token: "warning",
-                   },
-               },
-           ],
-       }
-  --> tests/html_macro/element-fail.rs:83:24
-   |
-83 |     html! { <div class=("deprecated", "warning") /> };
-   |                        ^^^^^^^^^^^^^^^^^^^^^^^^^
-
 error: the property value must be either a literal or enclosed in braces. Consider adding braces around your expression.: Expr::Tuple {
            attrs: [],
            paren_token: Paren,
            elems: [],
        }
-  --> tests/html_macro/element-fail.rs:84:24
+  --> tests/html_macro/element-fail.rs:80:24
    |
-84 |     html! { <input ref=() /> };
+80 |     html! { <input ref=() /> };
    |                        ^^
 
 error: the property value must be either a literal or enclosed in braces. Consider adding braces around your expression.: Expr::Tuple {
@@ -181,9 +157,9 @@ error: the property value must be either a literal or enclosed in braces. Consid
            paren_token: Paren,
            elems: [],
        }
-  --> tests/html_macro/element-fail.rs:85:24
+  --> tests/html_macro/element-fail.rs:81:24
    |
-85 |     html! { <input ref=() ref=() /> };
+81 |     html! { <input ref=() ref=() /> };
    |                        ^^
 
 error: the property value must be either a literal or enclosed in braces. Consider adding braces around your expression.: Expr::Call {
@@ -197,7 +173,7 @@ error: the property value must be either a literal or enclosed in braces. Consid
                        PathSegment {
                            ident: Ident {
                                ident: "Some",
-                               span: #0 bytes(2632..2636),
+                               span: #0 bytes(2482..2486),
                            },
                            arguments: PathArguments::None,
                        },
@@ -214,9 +190,9 @@ error: the property value must be either a literal or enclosed in braces. Consid
                },
            ],
        }
-  --> tests/html_macro/element-fail.rs:86:28
+  --> tests/html_macro/element-fail.rs:82:28
    |
-86 |     html! { <input onfocus=Some(5) /> };
+82 |     html! { <input onfocus=Some(5) /> };
    |                            ^^^^^^^
 
 error: the property value must be either a literal or enclosed in braces. Consider adding braces around your expression.: Expr::Path {
@@ -228,16 +204,16 @@ error: the property value must be either a literal or enclosed in braces. Consid
                    PathSegment {
                        ident: Ident {
                            ident: "NotToString",
-                           span: #0 bytes(2672..2683),
+                           span: #0 bytes(2522..2533),
                        },
                        arguments: PathArguments::None,
                    },
                ],
            },
        }
-  --> tests/html_macro/element-fail.rs:87:27
+  --> tests/html_macro/element-fail.rs:83:27
    |
-87 |     html! { <input string=NotToString /> };
+83 |     html! { <input string=NotToString /> };
    |                           ^^^^^^^^^^^
 
 error: the property value must be either a literal or enclosed in braces. Consider adding braces around your expression.: Expr::Call {
@@ -251,7 +227,7 @@ error: the property value must be either a literal or enclosed in braces. Consid
                        PathSegment {
                            ident: Ident {
                                ident: "Some",
-                               span: #0 bytes(2711..2715),
+                               span: #0 bytes(2561..2565),
                            },
                            arguments: PathArguments::None,
                        },
@@ -269,7 +245,7 @@ error: the property value must be either a literal or enclosed in braces. Consid
                            PathSegment {
                                ident: Ident {
                                    ident: "NotToString",
-                                   span: #0 bytes(2716..2727),
+                                   span: #0 bytes(2566..2577),
                                },
                                arguments: PathArguments::None,
                            },
@@ -278,9 +254,9 @@ error: the property value must be either a literal or enclosed in braces. Consid
                },
            ],
        }
-  --> tests/html_macro/element-fail.rs:88:22
+  --> tests/html_macro/element-fail.rs:84:22
    |
-88 |     html! { <a media=Some(NotToString) /> };
+84 |     html! { <a media=Some(NotToString) /> };
    |                      ^^^^^^^^^^^^^^^^^
 
 error: the property value must be either a literal or enclosed in braces. Consider adding braces around your expression.: Expr::Call {
@@ -294,7 +270,7 @@ error: the property value must be either a literal or enclosed in braces. Consid
                        PathSegment {
                            ident: Ident {
                                ident: "Some",
-                               span: #0 bytes(2755..2759),
+                               span: #0 bytes(2605..2609),
                            },
                            arguments: PathArguments::None,
                        },
@@ -311,9 +287,9 @@ error: the property value must be either a literal or enclosed in braces. Consid
                },
            ],
        }
-  --> tests/html_macro/element-fail.rs:89:21
+  --> tests/html_macro/element-fail.rs:85:21
    |
-89 |     html! { <a href=Some(5) /> };
+85 |     html! { <a href=Some(5) /> };
    |                     ^^^^^^^
 
 error: the property value must be either a literal or enclosed in braces. Consider adding braces around your expression.: Expr::Tuple {
@@ -321,9 +297,9 @@ error: the property value must be either a literal or enclosed in braces. Consid
            paren_token: Paren,
            elems: [],
        }
-  --> tests/html_macro/element-fail.rs:90:25
+  --> tests/html_macro/element-fail.rs:86:25
    |
-90 |     html! { <input type=() /> };
+86 |     html! { <input type=() /> };
    |                         ^^
 
 error: the property value must be either a literal or enclosed in braces. Consider adding braces around your expression.: Expr::Tuple {
@@ -331,9 +307,9 @@ error: the property value must be either a literal or enclosed in braces. Consid
            paren_token: Paren,
            elems: [],
        }
-  --> tests/html_macro/element-fail.rs:91:26
+  --> tests/html_macro/element-fail.rs:87:26
    |
-91 |     html! { <input value=() /> };
+87 |     html! { <input value=() /> };
    |                          ^^
 
 error: the property value must be either a literal or enclosed in braces. Consider adding braces around your expression.: Expr::Path {
@@ -345,26 +321,18 @@ error: the property value must be either a literal or enclosed in braces. Consid
                    PathSegment {
                        ident: Ident {
                            ident: "NotToString",
-                           span: #0 bytes(2862..2873),
+                           span: #0 bytes(2712..2723),
                        },
                        arguments: PathArguments::None,
                    },
                ],
            },
        }
-  --> tests/html_macro/element-fail.rs:92:27
+  --> tests/html_macro/element-fail.rs:88:27
    |
-92 |     html! { <input string=NotToString /> };
+88 |     html! { <input string=NotToString /> };
    |                           ^^^^^^^^^^^
 
-warning: use of deprecated function `compile_fail::deprecated_use_of_class`: the use of `(...)` with the attribute `class` is deprecated and will be removed in version 0.19. Use the `classes!` macro instead.
-  --> tests/html_macro/element-fail.rs:80:25
-   |
-80 |     html! { <div class={("deprecated", "warning")} /> };
-   |                         ^^^^^^^^^^^^^^^^^^^^^^^^^
-   |
-   = note: `#[warn(deprecated)]` on by default
-
 error[E0308]: mismatched types
   --> tests/html_macro/element-fail.rs:36:28
    |
@@ -662,10 +630,10 @@ error[E0277]: the trait bound `(): IntoPropValue<yew::NodeRef>` is not satisfied
    = note: this error originates in the macro `html` (in Nightly builds, run with -Z macro-backtrace for more info)
 
 error[E0277]: the trait bound `implicit_clone::unsync::IString: From<{integer}>` is not satisfied
-  --> tests/html_macro/element-fail.rs:77:15
+  --> tests/html_macro/element-fail.rs:77:16
    |
 77 |     html! { <@{55}></@> };
-   |               ^^^^ the trait `From<{integer}>` is not implemented for `implicit_clone::unsync::IString`
+   |                ^^ the trait `From<{integer}>` is not implemented for `implicit_clone::unsync::IString`
    |
    = help: the following other types implement trait `From<T>`:
              <implicit_clone::unsync::IString as From<&'static str>>
diff --git a/packages/yew-macro/tests/html_macro/generic-component-pass.rs b/packages/yew-macro/tests/html_macro/generic-component-pass.rs
index 4aca8a05457..856fff40fd8 100644
--- a/packages/yew-macro/tests/html_macro/generic-component-pass.rs
+++ b/packages/yew-macro/tests/html_macro/generic-component-pass.rs
@@ -76,24 +76,24 @@ where
 }
 
 fn compile_pass() {
-    ::yew::html! { <Generic<::std::string::String> /> };
-    ::yew::html! { <Generic<(u8, bool)> /> };
-    ::yew::html! { <Generic<(u8, bool)> ></Generic<(u8, bool)>> };
-    ::yew::html! { <Generic<::std::string::String> ></Generic<::std::string::String>> };
+    _ = ::yew::html! { <Generic<::std::string::String> /> };
+    _ = ::yew::html! { <Generic<(u8, bool)> /> };
+    _ = ::yew::html! { <Generic<(u8, bool)> ></Generic<(u8, bool)>> };
+    _ = ::yew::html! { <Generic<::std::string::String> ></Generic<::std::string::String>> };
 
-    ::yew::html! { <Generic<::std::vec::Vec<::std::string::String>> /> };
-    ::yew::html! { <Generic<::std::vec::Vec<::std::string::String>>></ Generic<::std::vec::Vec<::std::string::String>>> };
+    _ = ::yew::html! { <Generic<::std::vec::Vec<::std::string::String>> /> };
+    _ = ::yew::html! { <Generic<::std::vec::Vec<::std::string::String>>></ Generic<::std::vec::Vec<::std::string::String>>> };
 
-    ::yew::html! { <Generic<::std::primitive::usize> /> };
-    ::yew::html! { <Generic<::std::primitive::usize>></Generic<::std::primitive::usize>> };
-    ::yew::html! { <Generic<::std::string::String, > /> };
-    ::yew::html! { <Generic<::std::string::String, >></Generic<::std::string::String,>> };
+    _ = ::yew::html! { <Generic<::std::primitive::usize> /> };
+    _ = ::yew::html! { <Generic<::std::primitive::usize>></Generic<::std::primitive::usize>> };
+    _ = ::yew::html! { <Generic<::std::string::String, > /> };
+    _ = ::yew::html! { <Generic<::std::string::String, >></Generic<::std::string::String,>> };
 
-    ::yew::html! { <Generic2<::std::string::String, ::std::string::String> /> };
-    ::yew::html! { <Generic2<::std::string::String, ::std::string::String>></Generic2<::std::string::String, ::std::string::String>> };
+    _ = ::yew::html! { <Generic2<::std::string::String, ::std::string::String> /> };
+    _ = ::yew::html! { <Generic2<::std::string::String, ::std::string::String>></Generic2<::std::string::String, ::std::string::String>> };
 
-    ::yew::html! { <Generic2<::std::string::String, ::std::string::String, > /> };
-    ::yew::html! { <Generic2<::std::string::String, ::std::string::String, >></Generic2<::std::string::String, ::std::string::String, >> };
+    _ = ::yew::html! { <Generic2<::std::string::String, ::std::string::String, > /> };
+    _ = ::yew::html! { <Generic2<::std::string::String, ::std::string::String, >></Generic2<::std::string::String, ::std::string::String, >> };
 }
 
 fn main() {}
diff --git a/packages/yew-macro/tests/html_macro/html-element-pass.rs b/packages/yew-macro/tests/html_macro/html-element-pass.rs
index dc81c66db22..5c05322b050 100644
--- a/packages/yew-macro/tests/html_macro/html-element-pass.rs
+++ b/packages/yew-macro/tests/html_macro/html-element-pass.rs
@@ -48,7 +48,7 @@ fn compile_pass() {
 
     let attr_val_none: ::std::option::Option<::yew::virtual_dom::AttrValue> = ::std::option::Option::None;
 
-    ::yew::html! {
+    _ = ::yew::html! {
         <div>
             <div data-key="abc"></div>
             <div ref={&parent_ref}></div>
@@ -92,8 +92,7 @@ fn compile_pass() {
             </@>
 
             <@{
-                let tag = dyn_tag();
-                if tag == "test" {
+                if dyn_tag() == "test" {
                     "div"
                 } else {
                     "a"
@@ -113,17 +112,17 @@ fn compile_pass() {
         ::yew::html! { <span>{ "Hello" }</span> },
         ::yew::html! { <span>{ "World" }</span> },
     ];
-    ::yew::html! { <div>{children}</div> };
+    _ = ::yew::html! { <div>{children}</div> };
 
     // handle misleading angle brackets
-    ::yew::html! { <div data-val={<::std::string::String as ::std::default::Default>::default()}></div> };
-    ::yew::html! { <div><a data-val={<::std::string::String as ::std::default::Default>::default()} /></div> };
+    _ = ::yew::html! { <div data-val={<::std::string::String as ::std::default::Default>::default()}></div> };
+    _ = ::yew::html! { <div><a data-val={<::std::string::String as ::std::default::Default>::default()} /></div> };
 
     // test for https://github.com/yewstack/yew/issues/2810
-    ::yew::html! {  <div data-type="date" data-as="calender" /> };
+    _ = ::yew::html! {  <div data-type="date" data-as="calender" /> };
 
     let option_vnode = ::std::option::Option::Some(::yew::html! {});
-    ::yew::html! { <div>{option_vnode}</div> };
+    _ = ::yew::html! { <div>{option_vnode}</div> };
 }
 
 fn main() {}
diff --git a/packages/yew-macro/tests/html_macro/html-if-pass.rs b/packages/yew-macro/tests/html_macro/html-if-pass.rs
index aa95ba9d1d7..59ce730dcbf 100644
--- a/packages/yew-macro/tests/html_macro/html-if-pass.rs
+++ b/packages/yew-macro/tests/html_macro/html-if-pass.rs
@@ -1,35 +1,35 @@
 #![no_implicit_prelude]
 
 fn compile_pass_lit() {
-    ::yew::html! { if true {} };
-    ::yew::html! { if true { <div/> } };
-    ::yew::html! { if true { <div/><div/> } };
-    ::yew::html! { if true { <><div/><div/></> } };
-    ::yew::html! { if true { { ::yew::html! {} } } };
-    ::yew::html! { if true { { { let _x = 42; ::yew::html! {} } } } };
-    ::yew::html! { if true {} else {} };
-    ::yew::html! { if true {} else if true {} };
-    ::yew::html! { if true {} else if true {} else {} };
-    ::yew::html! { if let ::std::option::Option::Some(text) = ::std::option::Option::Some("text") { <span>{ text }</span> } };
-    ::yew::html! { <><div/>if true {}<div/></> };
-    ::yew::html! { <div>if true {}</div> };
+    _ = ::yew::html! { if true {} };
+    _ = ::yew::html! { if true { <div/> } };
+    _ = ::yew::html! { if true { <div/><div/> } };
+    _ = ::yew::html! { if true { <><div/><div/></> } };
+    _ = ::yew::html! { if true { { ::yew::html! {} } } };
+    _ = ::yew::html! { if true { { { let _x = 42; ::yew::html! {} } } } };
+    _ = ::yew::html! { if true {} else {} };
+    _ = ::yew::html! { if true {} else if true {} };
+    _ = ::yew::html! { if true {} else if true {} else {} };
+    _ = ::yew::html! { if let ::std::option::Option::Some(text) = ::std::option::Option::Some("text") { <span>{ text }</span> } };
+    _ = ::yew::html! { <><div/>if true {}<div/></> };
+    _ = ::yew::html! { <div>if true {}</div> };
 }
 
 fn compile_pass_expr() {
     let condition = true;
 
-    ::yew::html! { if condition {} };
-    ::yew::html! { if condition { <div/> } };
-    ::yew::html! { if condition { <div/><div/> } };
-    ::yew::html! { if condition { <><div/><div/></> } };
-    ::yew::html! { if condition { { ::yew::html! {} } } };
-    ::yew::html! { if condition { { { let _x = 42; ::yew::html! {} } } } };
-    ::yew::html! { if condition {} else {} };
-    ::yew::html! { if condition {} else if condition {} };
-    ::yew::html! { if condition {} else if condition {} else {} };
-    ::yew::html! { if let ::std::option::Option::Some(text) = ::std::option::Option::Some("text") { <span>{ text }</span> } };
-    ::yew::html! { <><div/>if condition {}<div/></> };
-    ::yew::html! { <div>if condition {}</div> };
+    _ = ::yew::html! { if condition {} };
+    _ = ::yew::html! { if condition { <div/> } };
+    _ = ::yew::html! { if condition { <div/><div/> } };
+    _ = ::yew::html! { if condition { <><div/><div/></> } };
+    _ = ::yew::html! { if condition { { ::yew::html! {} } } };
+    _ = ::yew::html! { if condition { { { let _x = 42; ::yew::html! {} } } } };
+    _ = ::yew::html! { if condition {} else {} };
+    _ = ::yew::html! { if condition {} else if condition {} };
+    _ = ::yew::html! { if condition {} else if condition {} else {} };
+    _ = ::yew::html! { if let ::std::option::Option::Some(text) = ::std::option::Option::Some("text") { <span>{ text }</span> } };
+    _ = ::yew::html! { <><div/>if condition {}<div/></> };
+    _ = ::yew::html! { <div>if condition {}</div> };
 }
 
 fn main() {}
diff --git a/packages/yew-macro/tests/html_macro/html-node-pass.rs b/packages/yew-macro/tests/html_macro/html-node-pass.rs
index a8c9dd1f7b3..d1a05d4c759 100644
--- a/packages/yew-macro/tests/html_macro/html-node-pass.rs
+++ b/packages/yew-macro/tests/html_macro/html-node-pass.rs
@@ -37,23 +37,23 @@ pub struct u8;
 pub struct usize;
 
 fn compile_pass() {
-    ::yew::html! { "" };
-    ::yew::html! { 'a' };
-    ::yew::html! { "hello" };
-    ::yew::html! { 42 };
-    ::yew::html! { 1.234 };
+    _ = ::yew::html! { "" };
+    _ = ::yew::html! { 'a' };
+    _ = ::yew::html! { "hello" };
+    _ = ::yew::html! { 42 };
+    _ = ::yew::html! { 1.234 };
 
-    ::yew::html! { <span>{ "" }</span> };
-    ::yew::html! { <span>{ 'a' }</span> };
-    ::yew::html! { <span>{ "hello" }</span> };
-    ::yew::html! { <span>{ 42 }</span> };
-    ::yew::html! { <span>{ 1.234 }</span> };
+    _ = ::yew::html! { <span>{ "" }</span> };
+    _ = ::yew::html! { <span>{ 'a' }</span> };
+    _ = ::yew::html! { <span>{ "hello" }</span> };
+    _ = ::yew::html! { <span>{ 42 }</span> };
+    _ = ::yew::html! { <span>{ 1.234 }</span> };
 
-    ::yew::html! { ::std::format!("Hello") };
-    ::yew::html! { {<::std::string::String as ::std::convert::From<&::std::primitive::str>>::from("Hello") } };
+    _ = ::yew::html! { ::std::format!("Hello") };
+    _ = ::yew::html! { {<::std::string::String as ::std::convert::From<&::std::primitive::str>>::from("Hello") } };
 
     let msg = "Hello";
-    ::yew::html! { msg };
+    _ = ::yew::html! { msg };
 }
 
 fn main() {}
diff --git a/packages/yew-macro/tests/html_macro/iterable-pass.rs b/packages/yew-macro/tests/html_macro/iterable-pass.rs
index 18eadf7b042..1f41185f3a2 100644
--- a/packages/yew-macro/tests/html_macro/iterable-pass.rs
+++ b/packages/yew-macro/tests/html_macro/iterable-pass.rs
@@ -45,13 +45,13 @@ fn empty_iter() -> impl ::std::iter::Iterator<Item = ::yew::Html> {
 }
 
 fn main() {
-    ::yew::html! { for empty_iter() };
-    ::yew::html! { for { empty_iter() } };
+    _ = ::yew::html! { for empty_iter() };
+    _ = ::yew::html! { for { empty_iter() } };
 
     let empty = empty_vec();
-    ::yew::html! { for empty };
+    _ = ::yew::html! { for empty };
 
-    ::yew::html! { for empty_vec() };
-    ::yew::html! { for ::std::iter::IntoIterator::into_iter(empty_vec()) };
-    ::yew::html! { for ::std::iter::Iterator::map(0..3, |num| { ::yew::html! { <span>{ num }</span> } }) };
+    _ = ::yew::html! { for empty_vec() };
+    _ = ::yew::html! { for ::std::iter::IntoIterator::into_iter(empty_vec()) };
+    _ = ::yew::html! { for ::std::iter::Iterator::map(0..3, |num| { ::yew::html! { <span>{ num }</span> } }) };
 }
diff --git a/packages/yew-macro/tests/html_macro/list-pass.rs b/packages/yew-macro/tests/html_macro/list-pass.rs
index 3cbe619eaeb..380e4792d1a 100644
--- a/packages/yew-macro/tests/html_macro/list-pass.rs
+++ b/packages/yew-macro/tests/html_macro/list-pass.rs
@@ -37,15 +37,15 @@ pub struct u8;
 pub struct usize;
 
 fn main() {
-    ::yew::html! {};
-    ::yew::html! { <></> };
-    ::yew::html! {
+    _ = ::yew::html! {};
+    _ = ::yew::html! { <></> };
+    _ = ::yew::html! {
         <>
             <></>
             <></>
         </>
     };
-    ::yew::html! {
+    _ = ::yew::html! {
         <key={::std::string::ToString::to_string("key")}>
         </>
     };
@@ -54,5 +54,5 @@ fn main() {
         ::yew::html! { <span>{ "Hello" }</span> },
         ::yew::html! { <span>{ "World" }</span> },
     ];
-    ::yew::html! { <>{ children }</> };
+    _ = ::yew::html! { <>{ children }</> };
 }
diff --git a/packages/yew-macro/tests/html_macro/node-pass.rs b/packages/yew-macro/tests/html_macro/node-pass.rs
index 1dfaea9c8a1..ed38c3e77cf 100644
--- a/packages/yew-macro/tests/html_macro/node-pass.rs
+++ b/packages/yew-macro/tests/html_macro/node-pass.rs
@@ -37,23 +37,23 @@ pub struct u8;
 pub struct usize;
 
 fn main() {
-    ::yew::html! { "" };
-    ::yew::html! { 'a' };
-    ::yew::html! { "hello" };
-    ::yew::html! { "42" };
-    ::yew::html! { "1.234" };
-    ::yew::html! { "true" };
+    _ = ::yew::html! { "" };
+    _ = ::yew::html! { 'a' };
+    _ = ::yew::html! { "hello" };
+    _ = ::yew::html! { "42" };
+    _ = ::yew::html! { "1.234" };
+    _ = ::yew::html! { "true" };
 
-    ::yew::html! { <span>{ "" }</span> };
-    ::yew::html! { <span>{ 'a' }</span> };
-    ::yew::html! { <span>{ "hello" }</span> };
-    ::yew::html! { <span>{ "42" }</span> };
-    ::yew::html! { <span>{ "1.234" }</span> };
-    ::yew::html! { <span>{ "true" }</span> };
+    _ = ::yew::html! { <span>{ "" }</span> };
+    _ = ::yew::html! { <span>{ 'a' }</span> };
+    _ = ::yew::html! { <span>{ "hello" }</span> };
+    _ = ::yew::html! { <span>{ "42" }</span> };
+    _ = ::yew::html! { <span>{ "1.234" }</span> };
+    _ = ::yew::html! { <span>{ "true" }</span> };
 
-    ::yew::html! { ::std::format!("Hello") };
-    ::yew::html! { ::std::string::ToString::to_string("Hello") };
+    _ = ::yew::html! { ::std::format!("Hello") };
+    _ = ::yew::html! { ::std::string::ToString::to_string("Hello") };
 
     let msg = "Hello";
-    ::yew::html! { msg };
+    _ = ::yew::html! { msg };
 }
diff --git a/packages/yew-macro/tests/html_macro/svg-pass.rs b/packages/yew-macro/tests/html_macro/svg-pass.rs
index eb1bb3a0963..f333c265203 100644
--- a/packages/yew-macro/tests/html_macro/svg-pass.rs
+++ b/packages/yew-macro/tests/html_macro/svg-pass.rs
@@ -39,7 +39,7 @@ pub struct usize;
 fn main() {
     // Ensure Rust keywords can be used as element names.
     // See: #1771
-    ::yew::html! {
+    _ = ::yew::html! {
         <a class="btn btn-primary" href="https://example.org/">
             <svg class="bi" fill="currentColor">
                 <use href="/bootstrap-icons.svg#wrench"/>
@@ -49,7 +49,7 @@ fn main() {
     };
 
     // some general SVG
-    ::yew::html! {
+    _ = ::yew::html! {
         <svg width="149" height="147" viewBox="0 0 149 147" fill="none" xmlns="http://www.w3.org/2000/svg">
             <path d="M60.5776 13.8268L51.8673 42.6431L77.7475 37.331L60.5776 13.8268Z" fill="#DEB819"/>
             <path d="M108.361 94.9937L138.708 90.686L115.342 69.8642" stroke="black" stroke-width="4" stroke-linecap="round" stroke-linejoin="round"/>
diff --git a/packages/yew/src/dom_bundle/btag/mod.rs b/packages/yew/src/dom_bundle/btag/mod.rs
index 8a97c1ef33d..a376d3b1fc9 100644
--- a/packages/yew/src/dom_bundle/btag/mod.rs
+++ b/packages/yew/src/dom_bundle/btag/mod.rs
@@ -830,11 +830,11 @@ mod tests {
     fn dynamic_tags_work() {
         let (root, scope, parent) = setup_parent();
 
-        let elem = html! { <@{
+        let elem = html! { <@{{
             let mut builder = String::new();
             builder.push('a');
             builder
-        }/> };
+        }}/> };
 
         let (_, mut elem) = elem.attach(&root, &scope, &parent, DomSlot::at_end());
         let vtag = assert_btag_mut(&mut elem);