feat: Minimal support for types with const generics

compiler/pavexc/src/compiler/codegen/mod.rs

@@ -464,7 +464,7 @@ fn collect_type_package_ids(package_ids: &mut IndexSet<PackageId>, t: &Type) {
             for generic in &t.generic_arguments {
                 match generic {
                     GenericArgument::TypeParameter(t) => collect_type_package_ids(package_ids, t),
-                    GenericArgument::Lifetime(_) => {}
+                    GenericArgument::Lifetime(_) | GenericArgument::Const(_) => {}
                 }
             }
         }

compiler/pavexc/src/compiler/framework_rustdoc.rs

@@ -167,8 +167,16 @@ pub(crate) fn resolve_type_path(raw_path: &str, krate_collection: &CrateCollecti
                     }))
                 }
             }
-            rustdoc_types::GenericParamDefKind::Const { .. } => {
-                unimplemented!("const generic parameters are not supported yet")
+            rustdoc_types::GenericParamDefKind::Const { default, .. } => {
+                if let Some(default) = default {
+                    GenericArgument::Const(rustdoc_ir::ConstGenericArgument {
+                        value: default.clone(),
+                    })
+                } else {
+                    GenericArgument::Const(rustdoc_ir::ConstGenericArgument {
+                        value: generic_def.name.clone(),
+                    })
+                }
             }
         };
         generic_arguments.push(arg);

compiler/ui_tests/Cargo.toml

@@ -295,6 +295,8 @@ members = [
   "reflection/bitflags_are_supported/generated_app",
   "reflection/common_response_types_are_supported",
   "reflection/common_response_types_are_supported/generated_app",
+  "reflection/const_generics_are_supported",
+  "reflection/const_generics_are_supported/generated_app",
   "reflection/crate_resolution/dependencies_can_register_local_items",
   "reflection/crate_resolution/dependencies_can_register_local_items/generated_app",
   "reflection/crate_resolution/multiple_versions_for_the_same_crate_are_supported",

compiler/ui_tests/reflection/const_generics_are_supported/Cargo.toml

@@ -0,0 +1,17 @@
+[package]
+name = "app_e22d4bbe"
+version = "0.1.0"
+edition.workspace = true
+
+[lints.rust.unexpected_cfgs]
+level = "allow"
+check-cfg = ["cfg(pavex_ide_hint)"]
+
+[dependencies]
+workspace_hack = { version = "0.1", path = "../../workspace_hack" }
+
+[dependencies.pavex]
+workspace = true
+
+[dependencies.pavex_cli_client]
+workspace = true

compiler/ui_tests/reflection/const_generics_are_supported/diagnostics.dot

@@ -0,0 +1,45 @@
+digraph "* * - 0" {
+    0 [ label = "0| &pavex::router::AllowedMethods"]
+    1 [ label = "1| crate::route_0::Next0(&'a pavex::router::AllowedMethods) -> crate::route_0::Next0<'a>"]
+    2 [ label = "2| pavex::middleware::Next::new(crate::route_0::Next0<'a>) -> pavex::middleware::Next<crate::route_0::Next0<'a>>"]
+    3 [ label = "3| pavex::middleware::wrap_noop(pavex::middleware::Next<crate::route_0::Next0<'a>>) -> pavex::Response"]
+    4 [ label = "4| <pavex::Response as pavex::IntoResponse>::into_response(pavex::Response) -> pavex::Response"]
+    2 -> 3 [ ]
+    1 -> 2 [ ]
+    3 -> 4 [ ]
+    0 -> 1 [ ]
+}
+
+digraph "* * - 1" {
+    0 [ label = "0| &pavex::router::AllowedMethods"]
+    1 [ label = "1| pavex::router::default_fallback(&pavex::router::AllowedMethods) -> pavex::Response"]
+    2 [ label = "2| <pavex::Response as pavex::IntoResponse>::into_response(pavex::Response) -> pavex::Response"]
+    1 -> 2 [ ]
+    0 -> 1 [ ]
+}
+
+digraph "GET / - 0" {
+    0 [ label = "0| crate::route_1::Next0() -> crate::route_1::Next0"]
+    1 [ label = "1| pavex::middleware::Next::new(crate::route_1::Next0) -> pavex::middleware::Next<crate::route_1::Next0>"]
+    2 [ label = "2| pavex::middleware::wrap_noop(pavex::middleware::Next<crate::route_1::Next0>) -> pavex::Response"]
+    3 [ label = "3| <pavex::Response as pavex::IntoResponse>::into_response(pavex::Response) -> pavex::Response"]
+    1 -> 2 [ ]
+    0 -> 1 [ ]
+    2 -> 3 [ ]
+}
+
+digraph "GET / - 1" {
+    0 [ label = "0| app_e22d4bbe::character() -> app_e22d4bbe::CharConst<'a'>"]
+    1 [ label = "1| app_e22d4bbe::boolean() -> app_e22d4bbe::BoolConst<true>"]
+    2 [ label = "2| app_e22d4bbe::numeric() -> app_e22d4bbe::NumericConst<8>"]
+    3 [ label = "3| app_e22d4bbe::handler(app_e22d4bbe::NumericConst<8>, app_e22d4bbe::BoolConst<true>, app_e22d4bbe::CharConst<'a'>) -> pavex::Response"]
+    4 [ label = "4| <pavex::Response as pavex::IntoResponse>::into_response(pavex::Response) -> pavex::Response"]
+    0 -> 3 [ ]
+    1 -> 3 [ ]
+    2 -> 3 [ ]
+    3 -> 4 [ ]
+}
+
+digraph app_state {
+    0 [ label = "0| crate::ApplicationState() -> crate::ApplicationState"]
+}

compiler/ui_tests/reflection/const_generics_are_supported/expectations/app.rs

@@ -0,0 +1,174 @@
+//! Do NOT edit this code.
+//! It was automatically generated by Pavex.
+//! All manual edits will be lost next time the code is generated.
+extern crate alloc;
+struct ServerState {
+    router: Router,
+    #[allow(dead_code)]
+    application_state: ApplicationState,
+}
+#[derive(Debug, Clone, serde::Deserialize)]
+pub struct ApplicationConfig {}
+pub struct ApplicationState {}
+impl ApplicationState {
+    pub async fn new(
+        _app_config: crate::ApplicationConfig,
+    ) -> Result<crate::ApplicationState, crate::ApplicationStateError> {
+        Ok(Self::_new().await)
+    }
+    async fn _new() -> crate::ApplicationState {
+        crate::ApplicationState {}
+    }
+}
+#[derive(Debug, thiserror::Error)]
+pub enum ApplicationStateError {}
+pub fn run(
+    server_builder: pavex::server::Server,
+    application_state: ApplicationState,
+) -> pavex::server::ServerHandle {
+    async fn handler(
+        request: http::Request<hyper::body::Incoming>,
+        connection_info: Option<pavex::connection::ConnectionInfo>,
+        server_state: std::sync::Arc<ServerState>,
+    ) -> pavex::Response {
+        let (router, state) = (&server_state.router, &server_state.application_state);
+        router.route(request, connection_info, state).await
+    }
+    let router = Router::new();
+    let server_state = std::sync::Arc::new(ServerState {
+        router,
+        application_state,
+    });
+    server_builder.serve(handler, server_state)
+}
+struct Router {
+    router: matchit::Router<u32>,
+}
+impl Router {
+    /// Create a new router instance.
+    ///
+    /// This method is invoked once, when the server starts.
+    pub fn new() -> Self {
+        Self { router: Self::router() }
+    }
+    fn router() -> matchit::Router<u32> {
+        let mut router = matchit::Router::new();
+        router.insert("/", 0u32).unwrap();
+        router
+    }
+    pub async fn route(
+        &self,
+        request: http::Request<hyper::body::Incoming>,
+        _connection_info: Option<pavex::connection::ConnectionInfo>,
+        #[allow(unused)]
+        state: &ApplicationState,
+    ) -> pavex::Response {
+        let (request_head, _) = request.into_parts();
+        let request_head: pavex::request::RequestHead = request_head.into();
+        let Ok(matched_route) = self.router.at(&request_head.target.path()) else {
+            let allowed_methods: pavex::router::AllowedMethods = pavex::router::MethodAllowList::from_iter(
+                    vec![],
+                )
+                .into();
+            return route_0::entrypoint(&allowed_methods).await;
+        };
+        match matched_route.value {
+            0u32 => {
+                match &request_head.method {
+                    &pavex::http::Method::GET => route_1::entrypoint().await,
+                    _ => {
+                        let allowed_methods: pavex::router::AllowedMethods = pavex::router::MethodAllowList::from_iter([
+                                pavex::http::Method::GET,
+                            ])
+                            .into();
+                        route_0::entrypoint(&allowed_methods).await
+                    }
+                }
+            }
+            i => unreachable!("Unknown route id: {}", i),
+        }
+    }
+}
+pub mod route_0 {
+    pub async fn entrypoint<'a>(
+        s_0: &'a pavex::router::AllowedMethods,
+    ) -> pavex::Response {
+        let response = wrapping_0(s_0).await;
+        response
+    }
+    async fn stage_1<'a>(s_0: &'a pavex::router::AllowedMethods) -> pavex::Response {
+        let response = handler(s_0).await;
+        response
+    }
+    async fn wrapping_0(v0: &pavex::router::AllowedMethods) -> pavex::Response {
+        let v1 = crate::route_0::Next0 {
+            s_0: v0,
+            next: stage_1,
+        };
+        let v2 = pavex::middleware::Next::new(v1);
+        let v3 = pavex::middleware::wrap_noop(v2).await;
+        <pavex::Response as pavex::IntoResponse>::into_response(v3)
+    }
+    async fn handler(v0: &pavex::router::AllowedMethods) -> pavex::Response {
+        let v1 = pavex::router::default_fallback(v0).await;
+        <pavex::Response as pavex::IntoResponse>::into_response(v1)
+    }
+    struct Next0<'a, T>
+    where
+        T: std::future::Future<Output = pavex::Response>,
+    {
+        s_0: &'a pavex::router::AllowedMethods,
+        next: fn(&'a pavex::router::AllowedMethods) -> T,
+    }
+    impl<'a, T> std::future::IntoFuture for Next0<'a, T>
+    where
+        T: std::future::Future<Output = pavex::Response>,
+    {
+        type Output = pavex::Response;
+        type IntoFuture = T;
+        fn into_future(self) -> Self::IntoFuture {
+            (self.next)(self.s_0)
+        }
+    }
+}
+pub mod route_1 {
+    pub async fn entrypoint() -> pavex::Response {
+        let response = wrapping_0().await;
+        response
+    }
+    async fn stage_1() -> pavex::Response {
+        let response = handler().await;
+        response
+    }
+    async fn wrapping_0() -> pavex::Response {
+        let v0 = crate::route_1::Next0 {
+            next: stage_1,
+        };
+        let v1 = pavex::middleware::Next::new(v0);
+        let v2 = pavex::middleware::wrap_noop(v1).await;
+        <pavex::Response as pavex::IntoResponse>::into_response(v2)
+    }
+    async fn handler() -> pavex::Response {
+        let v0 = app::character();
+        let v1 = app::boolean();
+        let v2 = app::numeric();
+        let v3 = app::handler(v2, v1, v0);
+        <pavex::Response as pavex::IntoResponse>::into_response(v3)
+    }
+    struct Next0<T>
+    where
+        T: std::future::Future<Output = pavex::Response>,
+    {
+        next: fn() -> T,
+    }
+    impl<T> std::future::IntoFuture for Next0<T>
+    where
+        T: std::future::Future<Output = pavex::Response>,
+    {
+        type Output = pavex::Response;
+        type IntoFuture = T;
+        fn into_future(self) -> Self::IntoFuture {
+            (self.next)()
+        }
+    }
+}

compiler/ui_tests/reflection/const_generics_are_supported/expectations/diagnostics.dot

@@ -0,0 +1,41 @@
+digraph "* * - 0" {
+    0 [ label = "0| &pavex::router::AllowedMethods"]
+    1 [ label = "1| crate::route_0::Next0(&'a pavex::router::AllowedMethods) -> crate::route_0::Next0<'a>"]
+    2 [ label = "2| pavex::middleware::Next::new(crate::route_0::Next0<'a>) -> pavex::middleware::Next<crate::route_0::Next0<'a>>"]
+    3 [ label = "3| pavex::middleware::wrap_noop(pavex::middleware::Next<crate::route_0::Next0<'a>>) -> pavex::Response"]
+    4 [ label = "4| <pavex::Response as pavex::IntoResponse>::into_response(pavex::Response) -> pavex::Response"]
+    2 -> 3 [ ]
+    1 -> 2 [ ]
+    3 -> 4 [ ]
+    0 -> 1 [ ]
+}
+digraph "* * - 1" {
+    0 [ label = "0| &pavex::router::AllowedMethods"]
+    1 [ label = "1| pavex::router::default_fallback(&pavex::router::AllowedMethods) -> pavex::Response"]
+    2 [ label = "2| <pavex::Response as pavex::IntoResponse>::into_response(pavex::Response) -> pavex::Response"]
+    1 -> 2 [ ]
+    0 -> 1 [ ]
+}
+digraph "GET / - 0" {
+    0 [ label = "0| crate::route_1::Next0() -> crate::route_1::Next0"]
+    1 [ label = "1| pavex::middleware::Next::new(crate::route_1::Next0) -> pavex::middleware::Next<crate::route_1::Next0>"]
+    2 [ label = "2| pavex::middleware::wrap_noop(pavex::middleware::Next<crate::route_1::Next0>) -> pavex::Response"]
+    3 [ label = "3| <pavex::Response as pavex::IntoResponse>::into_response(pavex::Response) -> pavex::Response"]
+    1 -> 2 [ ]
+    0 -> 1 [ ]
+    2 -> 3 [ ]
+}
+digraph "GET / - 1" {
+    0 [ label = "0| app::character() -> app::CharConst<'a'>"]
+    1 [ label = "1| app::boolean() -> app::BoolConst<true>"]
+    2 [ label = "2| app::numeric() -> app::NumericConst<8>"]
+    3 [ label = "3| app::handler(app::NumericConst<8>, app::BoolConst<true>, app::CharConst<'a'>) -> pavex::Response"]
+    4 [ label = "4| <pavex::Response as pavex::IntoResponse>::into_response(pavex::Response) -> pavex::Response"]
+    0 -> 3 [ ]
+    1 -> 3 [ ]
+    2 -> 3 [ ]
+    3 -> 4 [ ]
+}
+digraph app_state {
+    0 [ label = "0| crate::ApplicationState() -> crate::ApplicationState"]
+}

compiler/ui_tests/reflection/const_generics_are_supported/generated_app/Cargo.toml

@@ -0,0 +1,17 @@
+[package]
+name = "application_e22d4bbe"
+version = "0.1.0"
+edition = "2024"
+
+[package.metadata.px.generate]
+generator_type = "cargo_workspace_binary"
+generator_name = "app_e22d4bbe"
+
+[dependencies]
+app_e22d4bbe = { version = "0.1", path = "..", default-features = false }
+http = { version = "1", default-features = false }
+hyper = { version = "1", default-features = false }
+matchit = { version = "0.9", default-features = false }
+pavex = { version = "0.2", path = "../../../../../runtime/pavex", default-features = false }
+serde = { version = "1", default-features = false }
+thiserror = { version = "2", default-features = false }