fix(yew-router-macro): reject route params without corresponding fields

A unit variant like `Settings` with `#[at("/settings/{*_rest}")]`
compiled but produced a broken `to_path()` that returned the literal
pattern string. This was a pre-existing bug (same with the old
`*rest` syntax) now caught at compile time.

Also fixes the nested-router docs examples to use named fields.

Author: Madoshakalaka

packages/yew-router-macro/src/routable_derive.rs

@@ -8,6 +8,25 @@ use syn::{Data, DeriveInput, Fields, Ident, LitStr, Variant};
 const AT_ATTR_IDENT: &str = "at";
 const NOT_FOUND_ATTR_IDENT: &str = "not_found";
 
+/// Extract parameter names from a matchit-style route pattern.
+/// E.g. `"/posts/{id}"` → `["id"]`, `"/files/{*path}"` → `["path"]`.
+fn extract_route_params(route: &str) -> Vec<String> {
+    let mut params = Vec::new();
+    let mut chars = route.chars().peekable();
+    while let Some(c) = chars.next() {
+        if c == '{' {
+            if chars.peek() == Some(&'*') {
+                chars.next();
+            }
+            let name: String = chars.by_ref().take_while(|&c| c != '}').collect();
+            if !name.is_empty() {
+                params.push(name);
+            }
+        }
+    }
+    params
+}
+
 pub struct Routable {
     ident: Ident,
     ats: Vec<LitStr>,
@@ -101,6 +120,32 @@ fn parse_variants_attributes(
             ));
         }
 
+        let route_params = extract_route_params(&val);
+        if !route_params.is_empty() {
+            let field_names: std::collections::HashSet<String> = match &variant.fields {
+                Fields::Named(fields) => fields
+                    .named
+                    .iter()
+                    .filter_map(|f| f.ident.as_ref().map(|i| i.to_string()))
+                    .collect(),
+                Fields::Unit => std::collections::HashSet::new(),
+                Fields::Unnamed(_) => unreachable!(),
+            };
+
+            for param in &route_params {
+                if !field_names.contains(param) {
+                    return Err(syn::Error::new_spanned(
+                        &lit,
+                        format!(
+                            "route parameter `{param}` does not have a corresponding field in \
+                             variant `{}`",
+                            variant.ident
+                        ),
+                    ));
+                }
+            }
+        }
+
         ats.push(lit);
 
         for attr in attrs.iter() {

packages/yew-router-macro/tests/routable_derive/param-without-field-fail.rs

@@ -0,0 +1,9 @@
+#[derive(yew_router::Routable, Debug, Clone, PartialEq)]
+enum Routes {
+    #[at("/")]
+    Home,
+    #[at("/settings/{*_rest}")]
+    Settings,
+}
+
+fn main() {}

packages/yew-router-macro/tests/routable_derive/param-without-field-fail.stderr

@@ -0,0 +1,5 @@
+error: route parameter `_rest` does not have a corresponding field in variant `Settings`
+ --> tests/routable_derive/param-without-field-fail.rs:5:10
+  |
+5 |     #[at("/settings/{*_rest}")]
+  |          ^^^^^^^^^^^^^^^^^^^^

website/docs/concepts/router.mdx

@@ -424,7 +424,7 @@ enum MainRoute {
     #[at("/settings")]
     SettingsRoot,
     #[at("/settings/{*_rest}")]
-    Settings,
+    Settings { _rest: String },
     #[not_found]
     #[at("/404")]
     NotFound,
@@ -448,7 +448,7 @@ fn switch_main(route: MainRoute) -> Html {
         MainRoute::Home => html! {<h1>{"Home"}</h1>},
         MainRoute::News => html! {<h1>{"News"}</h1>},
         MainRoute::Contact => html! {<h1>{"Contact"}</h1>},
-        MainRoute::SettingsRoot | MainRoute::Settings => html! { <Switch<SettingsRoute> render={switch_settings} /> },
+        MainRoute::SettingsRoot | MainRoute::Settings { .. } => html! { <Switch<SettingsRoute> render={switch_settings} /> },
         MainRoute::NotFound => html! {<h1>{"Not Found"}</h1>},
     }
 }

website/i18n/ja/docusaurus-plugin-content-docs/current/concepts/router.mdx

@@ -397,7 +397,7 @@ enum MainRoute {
     #[at("/settings")]
     SettingsRoot,
     #[at("/settings/{*_rest}")]
-    Settings,
+    Settings { _rest: String },
     #[not_found]
     #[at("/404")]
     NotFound,
@@ -421,7 +421,7 @@ fn switch_main(route: MainRoute) -> Html {
         MainRoute::Home => html! {<h1>{"Home"}</h1>},
         MainRoute::News => html! {<h1>{"News"}</h1>},
         MainRoute::Contact => html! {<h1>{"Contact"}</h1>},
-        MainRoute::SettingsRoot | MainRoute::Settings => html! { <Switch<SettingsRoute> render={switch_settings} /> },
+        MainRoute::SettingsRoot | MainRoute::Settings { .. } => html! { <Switch<SettingsRoute> render={switch_settings} /> },
         MainRoute::NotFound => html! {<h1>{"Not Found"}</h1>},
     }
 }

website/i18n/zh-Hans/docusaurus-plugin-content-docs/current/concepts/router.mdx

@@ -397,7 +397,7 @@ enum MainRoute {
     #[at("/settings")]
     SettingsRoot,
     #[at("/settings/{*_rest}")]
-    Settings,
+    Settings { _rest: String },
     #[not_found]
     #[at("/404")]
     NotFound,
@@ -421,7 +421,7 @@ fn switch_main(route: MainRoute) -> Html {
         MainRoute::Home => html! {<h1>{"Home"}</h1>},
         MainRoute::News => html! {<h1>{"News"}</h1>},
         MainRoute::Contact => html! {<h1>{"Contact"}</h1>},
-        MainRoute::SettingsRoot | MainRoute::Settings => html! { <Switch<SettingsRoute> render={switch_settings} /> },
+        MainRoute::SettingsRoot | MainRoute::Settings { .. } => html! { <Switch<SettingsRoute> render={switch_settings} /> },
         MainRoute::NotFound => html! {<h1>{"Not Found"}</h1>},
     }
 }

website/i18n/zh-Hant/docusaurus-plugin-content-docs/current/concepts/router.mdx

@@ -397,7 +397,7 @@ enum MainRoute {
     #[at("/settings")]
     SettingsRoot,
     #[at("/settings/{*_rest}")]
-    Settings,
+    Settings { _rest: String },
     #[not_found]
     #[at("/404")]
     NotFound,
@@ -421,7 +421,7 @@ fn switch_main(route: MainRoute) -> Html {
         MainRoute::Home => html! {<h1>{"Home"}</h1>},
         MainRoute::News => html! {<h1>{"News"}</h1>},
         MainRoute::Contact => html! {<h1>{"Contact"}</h1>},
-        MainRoute::SettingsRoot | MainRoute::Settings => html! { <Switch<SettingsRoute> render={switch_settings} /> },
+        MainRoute::SettingsRoot | MainRoute::Settings { .. } => html! { <Switch<SettingsRoute> render={switch_settings} /> },
         MainRoute::NotFound => html! {<h1>{"Not Found"}</h1>},
     }
 }