phase 13.5: no-tokio Client construction

Cargo.toml

@@ -44,7 +44,12 @@ tokio = { version = "1", default-features = false, features = [
 tracing = { version = "0.1", default-features = false }
 
 [dev-dependencies]
-tokio = { version = "1", features = ["rt-multi-thread"] }
+# `critical-section/std` provides a host-platform impl so integration
+# tests that exercise `EmbassySyncChannels` (which depends on
+# `embassy-sync`'s critical-section calls) can link on host. This is
+# test-only; firmware builds supply their own platform impl.
+critical-section = { version = "1", features = ["std"] }
+tokio = { version = "1", features = ["rt-multi-thread", "macros", "time"] }
 tracing-subscriber = "0.3"
 
 [features]
@@ -92,3 +97,7 @@ bare_metal = ["dep:embassy-sync"]
 [[test]]
 name = "client_server"
 required-features = ["client-tokio", "server"]
+
+[[test]]
+name = "bare_metal_client"
+required-features = ["client", "bare_metal"]

examples/bare_metal/src/main.rs

@@ -58,27 +58,41 @@
 //! - Phase 12: `TransportSocket` GATs — `SendFuture` / `RecvFuture`
 //!   express `Send` bounds without RTN; `Socket = TokioSocket` pin
 //!   removed from `bind_*` functions
-//! - Phase 13 (partial): client-side feature-flag split. `client` no
-//!   longer pulls tokio + socket2; the tokio convenience defaults
+//! - Phase 13a: client-side feature-flag split. `client` no longer
+//!   pulls tokio + socket2; the tokio convenience defaults
 //!   (`Client::new`, `TokioSpawner`, etc.) live behind a new
 //!   `client-tokio` feature.
+//! - Phase 13.5: `Client` is now constructible without
+//!   `client-tokio`. `Inner` carries `F: TransportFactory` and
+//!   `T: Timer` generics, and the new
+//!   `Client::new_with_factory_spawner_timer_and_loopback`
+//!   constructor takes everything explicitly. Witness:
+//!   `tests/bare_metal_client.rs` (gated on `client + bare_metal`).
+//!   `service_registry` swapped its `HashMap` for `heapless::FnvIndexMap`.
+//!   `EmbassySyncChannels` extracted from `tokio_transport` to
+//!   `crate::embassy_channels` so it is reachable from no-tokio builds.
 //!
 //! **Remaining gaps:**
-//! 1. **Server-side feature-flag split** (Phase 13 server half,
-//!    deferred to Phase 14): `feature = "server"` still pulls in
-//!    tokio + socket2 because `server::sd_state` and
-//!    `server::subscription_manager` reference `tokio::net::UdpSocket`
-//!    / `tokio::sync::RwLock` / `socket2::Socket` directly. Phase 14
-//!    (server parallel) is the phase that retargets the server to the
-//!    trait surface; once that lands, `server` will gain the same
+//! 1. **Server-side feature-flag split** (deferred to Phase 14):
+//!    `feature = "server"` still pulls in tokio + socket2 because
+//!    `server::sd_state` and `server::subscription_manager` reference
+//!    `tokio::net::UdpSocket` / `tokio::sync::RwLock` /
+//!    `socket2::Socket` directly. Phase 14 retargets the server to
+//!    the trait surface; once that lands, `server` will gain the same
 //!    `server` + `server-tokio` split.
+//! 2. **No-alloc Client**: `Client` / `Inner` still depend on
+//!    `alloc` (heapless internals are fine, but `EmbassySyncChannels`
+//!    uses `Arc`, and `e2e_registry` uses `Arc<Mutex<_>>`). Phase 16
+//!    is the verification phase that lights up an alloc-panicking
+//!    harness; the no-alloc port itself is its own follow-on phase.
 //!
 //! # Recommendation for `no_alloc` consumers today
 //!
-//! Do NOT route through `Client::new_with_spawner_and_loopback`.
-//! Instead, depend on `simple-someip` with `default-features = false,
-//! features = ["bare_metal"]` and consume the already-portable layers
-//! directly:
+//! Do NOT route through `Client::new_with_factory_spawner_timer_and_loopback`
+//! on a strict `no_alloc` target — the run-loop still uses `Arc` for
+//! the embassy channel state. For now, depend on `simple-someip` with
+//! `default-features = false, features = ["bare_metal"]` and consume
+//! the already-portable layers directly:
 //!
 //! - `simple_someip::protocol` — wire format (headers, messages, SD
 //!   entries/options); zero-copy views for parsing.
@@ -413,8 +427,9 @@ fn main() {
     println!(
         "note: trait layer (TransportSocket + TransportFactory + Timer + \
          Spawner + ChannelFactory) exercised end-to-end. Phases 9-12 \
-         complete; phase 13 (client half) complete. Remaining: phase 14 \
-         server-trait retargeting + server-side `server-tokio` split. \
-         See top-of-file docblock."
+         complete; phases 13a + 13.5 (client + Client engine generic) \
+         complete. Remaining: phase 14 server-trait retargeting + \
+         server-side `server-tokio` split, then phase 16 no-alloc \
+         verification. See top-of-file docblock."
     );
 }

src/client/error.rs

@@ -21,9 +21,6 @@ pub enum Error {
     /// A SOME/IP protocol-level error.
     #[error(transparent)]
     Protocol(#[from] crate::protocol::Error),
-    /// An I/O error from the underlying network transport.
-    #[error(transparent)]
-    Io(#[from] std::io::Error),
     /// Received a discovery message that was not expected.
     #[error("Unexpected discovery message: {0:?}")]
     UnexpectedDiscoveryMessage(crate::protocol::Header),