[22.0.0] Change WASI trait impls back to being blanket impls (#8767)

* Change WASI trait impls back to being blanket impls (#8766)

This commit is a partial revert of #8609 to return `wasmtime-wasi` and
`wasmtime-wasi-http` back to using blanket impls. The main change from
before is to change the blanket impls to be in terms of a local newtype
wrapper to avoid trait coherence issues. This is done because otherwise
using the traits before required `&mut dyn WasiView` to exist but
sometimes only a `Foo<'a>` is held which is not easy to get a `&mut dyn
...` view of. By changing to a blanket impl in terms of a newtype
wrapper, `WasiImpl`, it's possible to call `bindgen!`-generated
`add_to_linker_get_host` functions with a return value of
`WasiImpl<Foo<'a>>` which enables hooking into all the generated
bindings.

* Update release notes

Author: alexcrichton

RELEASES.md

@@ -86,8 +86,9 @@ Unreleased.
   [#8610](https://github.com/bytecodealliance/wasmtime/pull/8610)
 
 * Implementations of `Host` traits in the `wasmtime-wasi` crate are now for
-  `dyn WasiView` instead of blanket impls for `T: WasiView`.
+  `WasiImpl<T>` instead of blanket impls for `T`.
   [#8609](https://github.com/bytecodealliance/wasmtime/pull/8609)
+  [#8766](https://github.com/bytecodealliance/wasmtime/pull/8766)
 
 * The concepts of "virtual sp offset" and "nominal sp" have been removed from all
   Cranelift backends.

crates/wasi-http/src/http_impl.rs

@@ -8,14 +8,17 @@ use crate::{
     error::internal_error,
     http_request_error,
     types::{HostFutureIncomingResponse, HostOutgoingRequest, OutgoingRequestConfig},
-    WasiHttpView,
+    WasiHttpImpl, WasiHttpView,
 };
 use bytes::Bytes;
 use http_body_util::{BodyExt, Empty};
 use hyper::Method;
 use wasmtime::component::Resource;
 
-impl outgoing_handler::Host for dyn WasiHttpView + '_ {
+impl<T> outgoing_handler::Host for WasiHttpImpl<T>
+where
+    T: WasiHttpView,
+{
     fn handle(
         &mut self,
         request_id: Resource<HostOutgoingRequest>,

crates/wasi-http/src/lib.rs

@@ -87,4 +87,4 @@ pub use crate::error::{
     http_request_error, hyper_request_error, hyper_response_error, HttpError, HttpResult,
 };
 #[doc(inline)]
-pub use crate::types::{WasiHttpCtx, WasiHttpView};
+pub use crate::types::{WasiHttpCtx, WasiHttpImpl, WasiHttpView};

crates/wasi-http/src/proxy.rs

@@ -3,7 +3,7 @@
 //! The implementation at the top of the module for use in async contexts,
 //! while the `sync` module provides implementation for use in sync contexts.
 
-use crate::WasiHttpView;
+use crate::{WasiHttpImpl, WasiHttpView};
 
 mod bindings {
     #![allow(missing_docs)]
@@ -83,7 +83,7 @@ pub fn add_to_linker<T>(l: &mut wasmtime::component::Linker<T>) -> anyhow::Resul
 where
     T: WasiHttpView + wasmtime_wasi::WasiView,
 {
-    let closure = type_annotate_wasi::<T, _>(|t| t);
+    let closure = type_annotate_wasi::<T, _>(|t| wasmtime_wasi::WasiImpl(t));
     wasmtime_wasi::bindings::clocks::wall_clock::add_to_linker_get_host(l, closure)?;
     wasmtime_wasi::bindings::clocks::monotonic_clock::add_to_linker_get_host(l, closure)?;
     wasmtime_wasi::bindings::io::poll::add_to_linker_get_host(l, closure)?;
@@ -101,13 +101,13 @@ where
 // obsolete.
 fn type_annotate_http<T, F>(val: F) -> F
 where
-    F: Fn(&mut T) -> &mut dyn WasiHttpView,
+    F: Fn(&mut T) -> WasiHttpImpl<&mut T>,
 {
     val
 }
 fn type_annotate_wasi<T, F>(val: F) -> F
 where
-    F: Fn(&mut T) -> &mut dyn wasmtime_wasi::WasiView,
+    F: Fn(&mut T) -> wasmtime_wasi::WasiImpl<&mut T>,
 {
     val
 }
@@ -117,7 +117,7 @@ pub fn add_only_http_to_linker<T>(l: &mut wasmtime::component::Linker<T>) -> any
 where
     T: WasiHttpView,
 {
-    let closure = type_annotate_http::<T, _>(|t| t);
+    let closure = type_annotate_http::<T, _>(|t| WasiHttpImpl(t));
     crate::bindings::http::outgoing_handler::add_to_linker_get_host(l, closure)?;
     crate::bindings::http::types::add_to_linker_get_host(l, closure)?;
 
@@ -126,7 +126,7 @@ where
 
 /// Sync implementation of the `wasi:http/proxy` world.
 pub mod sync {
-    use crate::WasiHttpView;
+    use crate::{WasiHttpImpl, WasiHttpView};
 
     mod bindings {
         #![allow(missing_docs)]
@@ -203,7 +203,7 @@ pub mod sync {
     where
         T: WasiHttpView + wasmtime_wasi::WasiView,
     {
-        let closure = super::type_annotate_wasi::<T, _>(|t| t);
+        let closure = super::type_annotate_wasi::<T, _>(|t| wasmtime_wasi::WasiImpl(t));
 
         wasmtime_wasi::bindings::clocks::wall_clock::add_to_linker_get_host(l, closure)?;
         wasmtime_wasi::bindings::clocks::monotonic_clock::add_to_linker_get_host(l, closure)?;
@@ -226,7 +226,7 @@ pub mod sync {
     where
         T: WasiHttpView,
     {
-        let closure = super::type_annotate_http::<T, _>(|t| t);
+        let closure = super::type_annotate_http::<T, _>(|t| WasiHttpImpl(t));
 
         crate::bindings::http::outgoing_handler::add_to_linker_get_host(l, closure)?;
         crate::bindings::http::types::add_to_linker_get_host(l, closure)?;

crates/wasi-http/src/types.rs

@@ -112,6 +112,83 @@ impl<T: ?Sized + WasiHttpView> WasiHttpView for &mut T {
     }
 }
 
+impl<T: ?Sized + WasiHttpView> WasiHttpView for Box<T> {
+    fn ctx(&mut self) -> &mut WasiHttpCtx {
+        T::ctx(self)
+    }
+
+    fn table(&mut self) -> &mut ResourceTable {
+        T::table(self)
+    }
+
+    fn new_response_outparam(
+        &mut self,
+        result: tokio::sync::oneshot::Sender<
+            Result<hyper::Response<HyperOutgoingBody>, types::ErrorCode>,
+        >,
+    ) -> wasmtime::Result<Resource<HostResponseOutparam>> {
+        T::new_response_outparam(self, result)
+    }
+
+    fn send_request(
+        &mut self,
+        request: hyper::Request<HyperOutgoingBody>,
+        config: OutgoingRequestConfig,
+    ) -> crate::HttpResult<HostFutureIncomingResponse> {
+        T::send_request(self, request, config)
+    }
+
+    fn is_forbidden_header(&mut self, name: &HeaderName) -> bool {
+        T::is_forbidden_header(self, name)
+    }
+}
+
+/// A concrete structure that all generated `Host` traits are implemented for.
+///
+/// This type serves as a small newtype wrapper to implement all of the `Host`
+/// traits for `wasi:http`. This type is internally used and is only needed if
+/// you're interacting with `add_to_linker` functions generated by bindings
+/// themselves (or `add_to_linker_get_host`).
+///
+/// This type is automatically used when using
+/// [`wasmtime_wasi_http::proxy::add_to_linker`](crate::proxy::add_to_linker)
+/// or
+/// [`wasmtime_wasi_http::proxy::sync::add_to_linker`](crate::proxy::sync::add_to_linker)
+/// and doesn't need to be manually configured.
+#[repr(transparent)]
+pub struct WasiHttpImpl<T>(pub T);
+
+impl<T: WasiHttpView> WasiHttpView for WasiHttpImpl<T> {
+    fn ctx(&mut self) -> &mut WasiHttpCtx {
+        self.0.ctx()
+    }
+
+    fn table(&mut self) -> &mut ResourceTable {
+        self.0.table()
+    }
+
+    fn new_response_outparam(
+        &mut self,
+        result: tokio::sync::oneshot::Sender<
+            Result<hyper::Response<HyperOutgoingBody>, types::ErrorCode>,
+        >,
+    ) -> wasmtime::Result<Resource<HostResponseOutparam>> {
+        self.0.new_response_outparam(result)
+    }
+
+    fn send_request(
+        &mut self,
+        request: hyper::Request<HyperOutgoingBody>,
+        config: OutgoingRequestConfig,
+    ) -> crate::HttpResult<HostFutureIncomingResponse> {
+        self.0.send_request(request, config)
+    }
+
+    fn is_forbidden_header(&mut self, name: &HeaderName) -> bool {
+        self.0.is_forbidden_header(name)
+    }
+}
+
 /// Returns `true` when the header is forbidden according to this [`WasiHttpView`] implementation.
 pub(crate) fn is_forbidden_header(view: &mut dyn WasiHttpView, name: &HeaderName) -> bool {
     static FORBIDDEN_HEADERS: [HeaderName; 10] = [

crates/wasi-http/src/types_impl.rs

@@ -8,7 +8,7 @@ use crate::{
         HostFutureIncomingResponse, HostIncomingRequest, HostIncomingResponse, HostOutgoingRequest,
         HostOutgoingResponse, HostResponseOutparam,
     },
-    WasiHttpView,
+    WasiHttpImpl, WasiHttpView,
 };
 use anyhow::Context;
 use std::any::Any;
@@ -19,7 +19,10 @@ use wasmtime_wasi::{
     Pollable, ResourceTableError,
 };
 
-impl crate::bindings::http::types::Host for dyn WasiHttpView + '_ {
+impl<T> crate::bindings::http::types::Host for WasiHttpImpl<T>
+where
+    T: WasiHttpView,
+{
     fn convert_error_code(&mut self, err: crate::HttpError) -> wasmtime::Result<types::ErrorCode> {
         err.downcast()
     }
@@ -98,7 +101,10 @@ fn get_fields_mut<'a>(
     }
 }
 
-impl crate::bindings::http::types::HostFields for dyn WasiHttpView + '_ {
+impl<T> crate::bindings::http::types::HostFields for WasiHttpImpl<T>
+where
+    T: WasiHttpView,
+{
     fn new(&mut self) -> wasmtime::Result<Resource<HostFields>> {
         let id = self
             .table()
@@ -285,7 +291,10 @@ impl crate::bindings::http::types::HostFields for dyn WasiHttpView + '_ {
     }
 }
 
-impl crate::bindings::http::types::HostIncomingRequest for dyn WasiHttpView + '_ {
+impl<T> crate::bindings::http::types::HostIncomingRequest for WasiHttpImpl<T>
+where
+    T: WasiHttpView,
+{
     fn method(&mut self, id: Resource<HostIncomingRequest>) -> wasmtime::Result<Method> {
         let method = self.table().get(&id)?.parts.method.clone();
         Ok(method.into())
@@ -370,7 +379,10 @@ impl crate::bindings::http::types::HostIncomingRequest for dyn WasiHttpView + '_
     }
 }
 
-impl crate::bindings::http::types::HostOutgoingRequest for dyn WasiHttpView + '_ {
+impl<T> crate::bindings::http::types::HostOutgoingRequest for WasiHttpImpl<T>
+where
+    T: WasiHttpView,
+{
     fn new(
         &mut self,
         headers: Resource<Headers>,
@@ -556,7 +568,10 @@ impl crate::bindings::http::types::HostOutgoingRequest for dyn WasiHttpView + '_
     }
 }
 
-impl crate::bindings::http::types::HostResponseOutparam for dyn WasiHttpView + '_ {
+impl<T> crate::bindings::http::types::HostResponseOutparam for WasiHttpImpl<T>
+where
+    T: WasiHttpView,
+{
     fn drop(&mut self, id: Resource<HostResponseOutparam>) -> wasmtime::Result<()> {
         let _ = self.table().delete(id)?;
         Ok(())
@@ -579,7 +594,10 @@ impl crate::bindings::http::types::HostResponseOutparam for dyn WasiHttpView + '
     }
 }
 
-impl crate::bindings::http::types::HostIncomingResponse for dyn WasiHttpView + '_ {
+impl<T> crate::bindings::http::types::HostIncomingResponse for WasiHttpImpl<T>
+where
+    T: WasiHttpView,
+{
     fn drop(&mut self, response: Resource<HostIncomingResponse>) -> wasmtime::Result<()> {
         let _ = self
             .table()
@@ -640,7 +658,10 @@ impl crate::bindings::http::types::HostIncomingResponse for dyn WasiHttpView + '
     }
 }
 
-impl crate::bindings::http::types::HostFutureTrailers for dyn WasiHttpView + '_ {
+impl<T> crate::bindings::http::types::HostFutureTrailers for WasiHttpImpl<T>
+where
+    T: WasiHttpView,
+{
     fn drop(&mut self, id: Resource<HostFutureTrailers>) -> wasmtime::Result<()> {
         let _ = self
             .table()
@@ -687,7 +708,10 @@ impl crate::bindings::http::types::HostFutureTrailers for dyn WasiHttpView + '_
     }
 }
 
-impl crate::bindings::http::types::HostIncomingBody for dyn WasiHttpView + '_ {
+impl<T> crate::bindings::http::types::HostIncomingBody for WasiHttpImpl<T>
+where
+    T: WasiHttpView,
+{
     fn stream(
         &mut self,
         id: Resource<HostIncomingBody>,
@@ -718,7 +742,10 @@ impl crate::bindings::http::types::HostIncomingBody for dyn WasiHttpView + '_ {
     }
 }
 
-impl crate::bindings::http::types::HostOutgoingResponse for dyn WasiHttpView + '_ {
+impl<T> crate::bindings::http::types::HostOutgoingResponse for WasiHttpImpl<T>
+where
+    T: WasiHttpView,
+{
     fn new(
         &mut self,
         headers: Resource<Headers>,
@@ -807,7 +834,10 @@ impl crate::bindings::http::types::HostOutgoingResponse for dyn WasiHttpView + '
     }
 }
 
-impl crate::bindings::http::types::HostFutureIncomingResponse for dyn WasiHttpView + '_ {
+impl<T> crate::bindings::http::types::HostFutureIncomingResponse for WasiHttpImpl<T>
+where
+    T: WasiHttpView,
+{
     fn drop(&mut self, id: Resource<HostFutureIncomingResponse>) -> wasmtime::Result<()> {
         let _ = self.table().delete(id)?;
         Ok(())
@@ -866,7 +896,10 @@ impl crate::bindings::http::types::HostFutureIncomingResponse for dyn WasiHttpVi
     }
 }
 
-impl crate::bindings::http::types::HostOutgoingBody for dyn WasiHttpView + '_ {
+impl<T> crate::bindings::http::types::HostOutgoingBody for WasiHttpImpl<T>
+where
+    T: WasiHttpView,
+{
     fn write(
         &mut self,
         id: Resource<HostOutgoingBody>,
@@ -903,7 +936,10 @@ impl crate::bindings::http::types::HostOutgoingBody for dyn WasiHttpView + '_ {
     }
 }
 
-impl crate::bindings::http::types::HostRequestOptions for dyn WasiHttpView + '_ {
+impl<T> crate::bindings::http::types::HostRequestOptions for WasiHttpImpl<T>
+where
+    T: WasiHttpView,
+{
     fn new(&mut self) -> wasmtime::Result<Resource<types::RequestOptions>> {
         let id = self.table().push(types::RequestOptions::default())?;
         Ok(id)

crates/wasi/src/ctx.rs

@@ -594,6 +594,39 @@ impl<T: ?Sized + WasiView> WasiView for &mut T {
     }
 }
 
+impl<T: ?Sized + WasiView> WasiView for Box<T> {
+    fn table(&mut self) -> &mut ResourceTable {
+        T::table(self)
+    }
+    fn ctx(&mut self) -> &mut WasiCtx {
+        T::ctx(self)
+    }
+}
+
+/// A small newtype wrapper which serves as the basis for implementations of
+/// `Host` WASI traits in this crate.
+///
+/// This type is used as the basis for the implementation of all `Host` traits
+/// generated by `bindgen!` for WASI interfaces. This is used automatically with
+/// [`add_to_linker_sync`](crate::add_to_linker_sync) and
+/// [`add_to_linker_async`](crate::add_to_linker_async).
+///
+/// This type is otherwise provided if you're calling the `add_to_linker`
+/// functions generated by `bindgen!` from the [`bindings`
+/// module](crate::bindings). In this situation you'll want to create a value of
+/// this type in the closures added to a `Linker`.
+#[repr(transparent)]
+pub struct WasiImpl<T>(pub T);
+
+impl<T: WasiView> WasiView for WasiImpl<T> {
+    fn table(&mut self) -> &mut ResourceTable {
+        T::table(&mut self.0)
+    }
+    fn ctx(&mut self) -> &mut WasiCtx {
+        T::ctx(&mut self.0)
+    }
+}
+
 /// Per-[`Store`] state which holds state necessary to implement WASI from this
 /// crate.
 ///