Move HostRef<T> into the C API crate

It isn't used by anything except for the C API and all of our embedder-exposed
APIs are already internally `Rc`-based, so it doesn't make sense to use with
them.

crates/c-api/src/extern.rs

@@ -1,6 +1,7 @@
+use crate::host_ref::HostRef;
 use crate::wasm_externkind_t;
 use crate::{wasm_externtype_t, wasm_func_t, wasm_global_t, wasm_memory_t, wasm_table_t};
-use wasmtime::{ExternType, Func, Global, HostRef, Memory, Table};
+use wasmtime::{ExternType, Func, Global, Memory, Table};
 
 #[derive(Clone)]
 pub struct wasm_extern_t {

crates/c-api/src/func.rs

@@ -1,3 +1,4 @@
+use crate::host_ref::HostRef;
 use crate::{wasm_extern_t, wasm_functype_t, wasm_store_t, wasm_val_t};
 use crate::{wasm_name_t, wasm_trap_t, wasmtime_error_t, ExternHost};
 use anyhow::anyhow;
@@ -5,7 +6,7 @@ use std::ffi::c_void;
 use std::panic::{self, AssertUnwindSafe};
 use std::ptr;
 use std::str;
-use wasmtime::{Caller, Extern, Func, HostRef, Trap};
+use wasmtime::{Caller, Extern, Func, Trap};
 
 #[derive(Clone)]
 #[repr(transparent)]

crates/c-api/src/global.rs

@@ -1,7 +1,8 @@
+use crate::host_ref::HostRef;
 use crate::{handle_result, wasmtime_error_t};
 use crate::{wasm_extern_t, wasm_globaltype_t, wasm_store_t, wasm_val_t, ExternHost};
 use std::ptr;
-use wasmtime::{Global, HostRef};
+use wasmtime::Global;
 
 #[derive(Clone)]
 #[repr(transparent)]

crates/c-api/src/host_ref.rs

@@ -0,0 +1,101 @@
+use std::any::Any;
+use std::cell::{self, RefCell};
+use std::convert::TryFrom;
+use std::marker::PhantomData;
+use wasmtime::{ExternRef, Store};
+
+/// Represents a piece of data located in the host environment.
+#[derive(Debug)]
+pub struct HostRef<T>
+where
+    T: 'static + Any,
+{
+    externref: ExternRef,
+    _phantom: PhantomData<T>,
+}
+
+impl<T> HostRef<T>
+where
+    T: 'static + Any,
+{
+    /// Creates a new `HostRef<T>` from `T`.
+    pub fn new(store: &Store, item: T) -> HostRef<T> {
+        HostRef {
+            externref: ExternRef::new(store, RefCell::new(item)),
+            _phantom: PhantomData,
+        }
+    }
+
+    /// Immutably borrows the wrapped data.
+    ///
+    /// # Panics
+    ///
+    /// Panics if the value is currently mutably borrowed.
+    pub fn borrow(&self) -> cell::Ref<T> {
+        self.inner().borrow()
+    }
+
+    /// Mutably borrows the wrapped data.
+    ///
+    /// # Panics
+    ///
+    /// Panics if the `HostRef<T>` is already borrowed.
+    pub fn borrow_mut(&self) -> cell::RefMut<T> {
+        self.inner().borrow_mut()
+    }
+
+    /// Returns true if the two `HostRef<T>`'s point to the same value (not just
+    /// values that compare as equal).
+    pub fn ptr_eq(&self, other: &HostRef<T>) -> bool {
+        self.externref.ptr_eq(&other.externref)
+    }
+
+    fn inner(&self) -> &RefCell<T> {
+        self.externref
+            .data()
+            .downcast_ref::<RefCell<T>>()
+            .expect("`HostRef<T>`s always wrap an `ExternRef` of `RefCell<T>`")
+    }
+}
+
+impl<T> AsRef<ExternRef> for HostRef<T> {
+    fn as_ref(&self) -> &ExternRef {
+        &self.externref
+    }
+}
+
+impl<T> From<HostRef<T>> for ExternRef
+where
+    T: 'static + Any,
+{
+    fn from(host: HostRef<T>) -> ExternRef {
+        host.externref
+    }
+}
+
+impl<T> TryFrom<ExternRef> for HostRef<T>
+where
+    T: 'static + Any,
+{
+    type Error = ExternRef;
+
+    fn try_from(externref: ExternRef) -> Result<Self, ExternRef> {
+        if externref.data().is::<RefCell<T>>() {
+            Ok(HostRef {
+                externref,
+                _phantom: PhantomData,
+            })
+        } else {
+            Err(externref)
+        }
+    }
+}
+
+impl<T> Clone for HostRef<T> {
+    fn clone(&self) -> HostRef<T> {
+        HostRef {
+            externref: self.externref.clone(),
+            _phantom: PhantomData,
+        }
+    }
+}

crates/c-api/src/instance.rs

@@ -1,9 +1,10 @@
+use crate::host_ref::HostRef;
 use crate::{wasm_extern_t, wasm_extern_vec_t, wasm_module_t, wasm_trap_t};
 use crate::{wasm_store_t, wasmtime_error_t, ExternHost};
 use anyhow::Result;
 use std::cell::RefCell;
 use std::ptr;
-use wasmtime::{Extern, HostRef, Instance, Store, Trap};
+use wasmtime::{Extern, Instance, Store, Trap};
 
 #[repr(C)]
 #[derive(Clone)]

crates/c-api/src/lib.rs

@@ -11,6 +11,7 @@ mod error;
 mod r#extern;
 mod func;
 mod global;
+mod host_ref;
 mod instance;
 mod linker;
 mod memory;

crates/c-api/src/linker.rs

@@ -1,8 +1,9 @@
+use crate::host_ref::HostRef;
 use crate::{bad_utf8, handle_result, wasmtime_error_t};
 use crate::{wasm_extern_t, wasm_store_t, ExternHost};
 use crate::{wasm_func_t, wasm_instance_t, wasm_module_t, wasm_name_t, wasm_trap_t};
 use std::str;
-use wasmtime::{Extern, HostRef, Linker};
+use wasmtime::{Extern, Linker};
 
 #[repr(C)]
 pub struct wasmtime_linker_t {

crates/c-api/src/memory.rs

@@ -1,5 +1,6 @@
+use crate::host_ref::HostRef;
 use crate::{wasm_extern_t, wasm_memorytype_t, wasm_store_t, ExternHost};
-use wasmtime::{HostRef, Memory};
+use wasmtime::Memory;
 
 #[derive(Clone)]
 #[repr(transparent)]

crates/c-api/src/module.rs

@@ -1,8 +1,9 @@
+use crate::host_ref::HostRef;
 use crate::{handle_result, wasmtime_error_t};
 use crate::{wasm_byte_vec_t, wasm_exporttype_vec_t, wasm_importtype_vec_t};
 use crate::{wasm_exporttype_t, wasm_importtype_t, wasm_store_t};
 use std::ptr;
-use wasmtime::{HostRef, Module};
+use wasmtime::Module;
 
 #[repr(C)]
 #[derive(Clone)]

crates/c-api/src/table.rs

@@ -1,7 +1,8 @@
+use crate::host_ref::HostRef;
 use crate::{handle_result, wasm_func_t, wasm_ref_t, wasmtime_error_t};
 use crate::{wasm_extern_t, wasm_store_t, wasm_tabletype_t, ExternHost};
 use std::ptr;
-use wasmtime::{HostRef, Table, Val};
+use wasmtime::{Table, Val};
 
 #[derive(Clone)]
 #[repr(transparent)]

crates/c-api/src/trap.rs

@@ -1,6 +1,7 @@
+use crate::host_ref::HostRef;
 use crate::{wasm_frame_vec_t, wasm_instance_t, wasm_name_t, wasm_store_t};
 use once_cell::unsync::OnceCell;
-use wasmtime::{HostRef, Store, Trap};
+use wasmtime::{Store, Trap};
 
 #[repr(C)]
 #[derive(Clone)]

crates/c-api/src/wasi.rs

@@ -1,4 +1,5 @@
 //! The WASI embedding API definitions for Wasmtime.
+use crate::host_ref::HostRef;
 use crate::{wasm_extern_t, wasm_importtype_t, wasm_store_t, wasm_trap_t, ExternHost};
 use anyhow::Result;
 use std::collections::HashMap;
@@ -12,7 +13,7 @@ use wasi_common::{
     old::snapshot_0::WasiCtxBuilder as WasiSnapshot0CtxBuilder, preopen_dir,
     WasiCtxBuilder as WasiPreview1CtxBuilder,
 };
-use wasmtime::{HostRef, Linker, Store, Trap};
+use wasmtime::{Linker, Store, Trap};
 use wasmtime_wasi::{old::snapshot_0::Wasi as WasiSnapshot0, Wasi as WasiPreview1};
 
 unsafe fn cstr_to_path<'a>(path: *const c_char) -> Option<&'a Path> {

crates/wasmtime/src/lib.rs

@@ -29,7 +29,7 @@ pub use crate::func::*;
 pub use crate::instance::Instance;
 pub use crate::linker::*;
 pub use crate::module::Module;
-pub use crate::r#ref::{ExternRef, HostRef};
+pub use crate::r#ref::ExternRef;
 pub use crate::runtime::*;
 pub use crate::trap::Trap;
 pub use crate::types::*;

crates/wasmtime/src/ref.rs

@@ -1,10 +1,8 @@
 #![allow(missing_docs)]
 
 use std::any::Any;
-use std::cell::{self, RefCell};
+use std::cell::RefCell;
-use std::convert::TryFrom;
 use std::fmt;
-use std::marker::PhantomData;
 use std::rc::{Rc, Weak};
 use wasmtime_runtime::VMExternRef;
 
@@ -81,99 +79,3 @@ impl fmt::Debug for ExternRef {
             .finish()
     }
 }
-
-/// Represents a piece of data located in the host environment.
-#[derive(Debug)]
-pub struct HostRef<T>
-where
-    T: 'static + Any,
-{
-    externref: ExternRef,
-    _phantom: PhantomData<T>,
-}
-
-impl<T> HostRef<T>
-where
-    T: 'static + Any,
-{
-    /// Creates a new `HostRef<T>` from `T`.
-    pub fn new(store: &crate::Store, item: T) -> HostRef<T> {
-        HostRef {
-            externref: ExternRef::new(store, RefCell::new(item)),
-            _phantom: PhantomData,
-        }
-    }
-
-    /// Immutably borrows the wrapped data.
-    ///
-    /// # Panics
-    ///
-    /// Panics if the value is currently mutably borrowed.
-    pub fn borrow(&self) -> cell::Ref<T> {
-        self.inner().borrow()
-    }
-
-    /// Mutably borrows the wrapped data.
-    ///
-    /// # Panics
-    ///
-    /// Panics if the `HostRef<T>` is already borrowed.
-    pub fn borrow_mut(&self) -> cell::RefMut<T> {
-        self.inner().borrow_mut()
-    }
-
-    /// Returns true if the two `HostRef<T>`'s point to the same value (not just
-    /// values that compare as equal).
-    pub fn ptr_eq(&self, other: &HostRef<T>) -> bool {
-        self.externref.ptr_eq(&other.externref)
-    }
-
-    fn inner(&self) -> &RefCell<T> {
-        self.externref
-            .inner
-            .downcast_ref::<RefCell<T>>()
-            .expect("`HostRef<T>`s always wrap an `ExternRef` of `RefCell<T>`")
-    }
-}
-
-impl<T> AsRef<ExternRef> for HostRef<T> {
-    fn as_ref(&self) -> &ExternRef {
-        &self.externref
-    }
-}
-
-impl<T> From<HostRef<T>> for ExternRef
-where
-    T: 'static + Any,
-{
-    fn from(host: HostRef<T>) -> ExternRef {
-        host.externref
-    }
-}
-
-impl<T> TryFrom<ExternRef> for HostRef<T>
-where
-    T: 'static + Any,
-{
-    type Error = ExternRef;
-
-    fn try_from(externref: ExternRef) -> Result<Self, ExternRef> {
-        if externref.inner.is::<RefCell<T>>() {
-            Ok(HostRef {
-                externref,
-                _phantom: PhantomData,
-            })
-        } else {
-            Err(externref)
-        }
-    }
-}
-
-impl<T> Clone for HostRef<T> {
-    fn clone(&self) -> HostRef<T> {
-        HostRef {
-            externref: self.externref.clone(),
-            _phantom: PhantomData,
-        }
-    }
-}