EqRef from_i31 implementation (#11884)

* feat(gc/eqref): from_i31 implementation

Copy of AnyRef's from_i31, exact same thing.

* test: case for EqRef's from_i31 implementation

Author: siaeyy

crates/wasmtime/src/runtime/gc/enabled/eqref.rs

@@ -1,8 +1,8 @@
 //! Working with GC `eqref`s.
 
 use crate::{
-    AnyRef, ArrayRef, ArrayType, AsContext, GcRefImpl, GcRootIndex, HeapType, I31, OwnedRooted,
-    RefType, Rooted, StructRef, StructType, ValRaw, ValType, WasmTy,
+    AnyRef, ArrayRef, ArrayType, AsContext, AsContextMut, GcRefImpl, GcRootIndex, HeapType, I31,
+    OwnedRooted, RefType, Rooted, StructRef, StructType, ValRaw, ValType, WasmTy,
     prelude::*,
     runtime::vm::VMGcRef,
     store::{AutoAssertNoGc, StoreOpaque},
@@ -248,6 +248,33 @@ impl EqRef {
         }
     }
 
+    /// Construct an `eqref` from an `i31`.
+    ///
+    /// # Example
+    ///
+    /// ```
+    /// # use wasmtime::*;
+    /// # fn _foo() -> Result<()> {
+    /// let mut store = Store::<()>::default();
+    ///
+    /// // Create an `i31`.
+    /// let i31 = I31::wrapping_u32(999);
+    ///
+    /// // Convert it into an `eqref`.
+    /// let eqref = EqRef::from_i31(&mut store, i31);
+    /// # Ok(())
+    /// # }
+    /// ```
+    pub fn from_i31(mut store: impl AsContextMut, value: I31) -> Rooted<Self> {
+        let mut store = AutoAssertNoGc::new(store.as_context_mut().0);
+        Self::_from_i31(&mut store, value)
+    }
+
+    pub(crate) fn _from_i31(store: &mut AutoAssertNoGc<'_>, value: I31) -> Rooted<Self> {
+        let gc_ref = VMGcRef::from_i31(value.runtime_i31());
+        Rooted::new(store, gc_ref)
+    }
+
     /// Is this `eqref` an `i31`?
     ///
     /// # Errors

tests/all/eqref.rs

@@ -0,0 +1,25 @@
+use wasmtime::*;
+
+#[test]
+fn eqref_from_i31() -> Result<()> {
+    let mut config = Config::new();
+    config.wasm_function_references(true);
+    config.wasm_gc(true);
+
+    let engine = Engine::new(&config)?;
+    let mut store = Store::new(&engine, ());
+
+    let i31 = I31::wrapping_u32(31);
+
+    // without EqRef::from_i31
+    let any_ref = AnyRef::from_i31(&mut store, i31);
+    let eq_ref1 = any_ref.unwrap_eqref(&mut store)?;
+
+    // with EqRef::from_i31
+    let eq_ref2 = EqRef::from_i31(&mut store, i31);
+
+    // reference to same i31
+    assert_eq!(Rooted::ref_eq(&store, &eq_ref1, &eq_ref2)?, true);
+
+    Ok(())
+}

tests/all/main.rs

@@ -13,6 +13,7 @@ mod custom_code_memory;
 mod debug;
 mod defaults;
 mod epoch_interruption;
+mod eqref;
 mod exceptions;
 mod exnrefs;
 mod externals;