Replace TryFrom with custom TryFromJsValue trait

This commit replaces the usage of the standard library's TryFrom trait with a custom TryFromJsValue trait added for handling the conversion from JavaScript values in WASM. This trait has been implemented for different types across multiple modules to ensure consistent error handling on failed conversions.

fixes rustwasm#3685

crates/backend/src/codegen.rs

@@ -297,10 +297,10 @@ impl ToTokens for ast::Struct {
             }
 
             #[allow(clippy::all)]
-            impl #wasm_bindgen::__rt::core::convert::TryFrom<#wasm_bindgen::JsValue> for #name {
+            impl #wasm_bindgen::convert::TryFromJsValue for #name {
                 type Error = #wasm_bindgen::JsValue;
 
-                fn try_from(value: #wasm_bindgen::JsValue)
+                fn try_from_js_value(value: #wasm_bindgen::JsValue)
                     -> #wasm_bindgen::__rt::std::result::Result<Self, Self::Error> {
                     let idx = #wasm_bindgen::convert::IntoWasmAbi::into_abi(&value);
 
@@ -822,6 +822,7 @@ impl ToTokens for ast::ImportType {
                 use #wasm_bindgen::convert::{IntoWasmAbi, FromWasmAbi};
                 use #wasm_bindgen::convert::{OptionIntoWasmAbi, OptionFromWasmAbi};
                 use #wasm_bindgen::convert::{RefFromWasmAbi, LongRefFromWasmAbi};
+                use #wasm_bindgen::convert::TryFromJsValue;
                 use #wasm_bindgen::describe::WasmDescribe;
                 use #wasm_bindgen::{JsValue, JsCast, JsObject};
                 use #wasm_bindgen::__rt::core;
@@ -1452,11 +1453,12 @@ impl ToTokens for ast::Enum {
             }
 
             #[allow(clippy::all)]
-            impl #wasm_bindgen::__rt::core::convert::TryFrom<#wasm_bindgen::JsValue> for #enum_name {
+            impl #wasm_bindgen::convert::TryFromJsValue for #enum_name {
                 type Error = #wasm_bindgen::JsValue;
 
-                fn try_from(value: #wasm_bindgen::JsValue)
-                    -> #wasm_bindgen::__rt::std::result::Result<Self, <#enum_name as #wasm_bindgen::__rt::core::convert::TryFrom<JsValue>>::Error> {
+                fn try_from_js_value(value: #wasm_bindgen::JsValue)
+                    -> #wasm_bindgen::__rt::std::result::Result<Self, <#enum_name as #wasm_bindgen::convert::TryFromJsValue>::Error> {
+                    use #wasm_bindgen::__rt::core::convert::TryFrom;
                     let js = f64::try_from(&value)? as u32;
 
                     #wasm_bindgen::__rt::std::result::Result::Ok(

src/convert/impls.rs

@@ -2,13 +2,13 @@ use core::char;
 use core::mem::{self, ManuallyDrop};
 
 use crate::convert::traits::{WasmAbi, WasmPrimitive};
+use crate::convert::TryFromJsValue;
 use crate::convert::{FromWasmAbi, IntoWasmAbi, LongRefFromWasmAbi, RefFromWasmAbi};
 use crate::convert::{OptionFromWasmAbi, OptionIntoWasmAbi, ReturnWasmAbi};
 use crate::{Clamped, JsError, JsValue, UnwrapThrowExt};
 
 if_std! {
     use std::boxed::Box;
-    use std::convert::{TryFrom, TryInto};
     use std::fmt::Debug;
     use std::vec::Vec;
 }
@@ -415,7 +415,7 @@ if_std! {
         js_vals.into_abi()
     }
 
-    pub unsafe fn js_value_vector_from_abi<T: TryFrom<JsValue>>(js: <Box<[JsValue]> as FromWasmAbi>::Abi) -> Box<[T]> where T::Error: Debug {
+    pub unsafe fn js_value_vector_from_abi<T: TryFromJsValue>(js: <Box<[JsValue]> as FromWasmAbi>::Abi) -> Box<[T]> where T::Error: Debug {
         let js_vals = <Vec<JsValue> as FromWasmAbi>::from_abi(js);
 
         let mut result = Vec::with_capacity(js_vals.len());
@@ -430,7 +430,7 @@ if_std! {
             // we're talking about, it can only see functions that actually make it to the
             // final wasm binary (i.e., not inlined functions). All of those internal
             // iterator functions get inlined in release mode, and so they don't show up.
-            result.push(value.try_into().expect_throw("array contains a value of the wrong type"));
+            result.push(T::try_from_js_value(value).expect_throw("array contains a value of the wrong type"));
         }
         result.into_boxed_slice()
     }

src/convert/traits.rs

@@ -2,6 +2,7 @@ use core::borrow::Borrow;
 use core::ops::{Deref, DerefMut};
 
 use crate::describe::*;
+use crate::JsValue;
 
 /// A trait for anything that can be converted into a type that can cross the
 /// wasm ABI directly, eg `u32` or `f64`.
@@ -249,3 +250,11 @@ impl<T: WasmAbi> WasmRet<T> {
         T::join(self.prim1, self.prim2, self.prim3, self.prim4)
     }
 }
+
+pub trait TryFromJsValue: Sized {
+    /// The type returned in the event of a conversion error.
+    type Error;
+
+    /// Performs the conversion.
+    fn try_from_js_value(value: JsValue) -> Result<Self, Self::Error>;
+}

src/lib.rs

@@ -815,6 +815,17 @@ if_std! {
             }
         }
     }
+
+    impl crate::convert::TryFromJsValue for String {
+        type Error = JsValue;
+
+        fn try_from_js_value(value: JsValue) -> Result<Self, Self::Error> {
+            match value.as_string() {
+                Some(s) => Ok(s),
+                None => Err(value),
+            }
+        }
+    }
 }
 
 impl From<bool> for JsValue {