Replace all Self identifiers in method argument and return types

CHANGELOG.md

@@ -29,6 +29,9 @@
 * Added `unsupported` crate to `wasm_bindgen_test(unsupported = test)` as a way of running tests on non-Wasm targets as well.
   [#4150](https://github.com/rustwasm/wasm-bindgen/pull/4150)
 
+* Added support for `Self` in complex type expressions in methods.
+  [#4155](https://github.com/rustwasm/wasm-bindgen/pull/4155)
+
 ### Changed
 
 * Implicitly enable reference type and multivalue transformations if the module already makes use of the corresponding target features.

crates/cli/tests/reference/raw.js

@@ -6,26 +6,6 @@ export function __wbg_set_wasm(val) {
 }
 
 
-const lTextDecoder = typeof TextDecoder === 'undefined' ? (0, module.require)('util').TextDecoder : TextDecoder;
-
-let cachedTextDecoder = new lTextDecoder('utf-8', { ignoreBOM: true, fatal: true });
-
-cachedTextDecoder.decode();
-
-let cachedUint8ArrayMemory0 = null;
-
-function getUint8ArrayMemory0() {
-    if (cachedUint8ArrayMemory0 === null || cachedUint8ArrayMemory0.byteLength === 0) {
-        cachedUint8ArrayMemory0 = new Uint8Array(wasm.memory.buffer);
-    }
-    return cachedUint8ArrayMemory0;
-}
-
-function getStringFromWasm0(ptr, len) {
-    ptr = ptr >>> 0;
-    return cachedTextDecoder.decode(getUint8ArrayMemory0().subarray(ptr, ptr + len));
-}
-
 const heap = new Array(128).fill(undefined);
 
 heap.push(undefined, null, true, false);
@@ -45,6 +25,26 @@ function takeObject(idx) {
     dropObject(idx);
     return ret;
 }
+
+const lTextDecoder = typeof TextDecoder === 'undefined' ? (0, module.require)('util').TextDecoder : TextDecoder;
+
+let cachedTextDecoder = new lTextDecoder('utf-8', { ignoreBOM: true, fatal: true });
+
+cachedTextDecoder.decode();
+
+let cachedUint8ArrayMemory0 = null;
+
+function getUint8ArrayMemory0() {
+    if (cachedUint8ArrayMemory0 === null || cachedUint8ArrayMemory0.byteLength === 0) {
+        cachedUint8ArrayMemory0 = new Uint8Array(wasm.memory.buffer);
+    }
+    return cachedUint8ArrayMemory0;
+}
+
+function getStringFromWasm0(ptr, len) {
+    ptr = ptr >>> 0;
+    return cachedTextDecoder.decode(getUint8ArrayMemory0().subarray(ptr, ptr + len));
+}
 /**
  * @param {number} test
  * @returns {number}
@@ -109,11 +109,11 @@ export function __wbg_test2_39fe629b9aa739cf() {
     return addHeapObject(ret);
 };
 
-export function __wbindgen_throw(arg0, arg1) {
-    throw new Error(getStringFromWasm0(arg0, arg1));
-};
-
 export function __wbindgen_object_drop_ref(arg0) {
     takeObject(arg0);
 };
 
+export function __wbindgen_throw(arg0, arg1) {
+    throw new Error(getStringFromWasm0(arg0, arg1));
+};
+

crates/macro-support/Cargo.toml

@@ -21,6 +21,6 @@ strict-macro = []
 [dependencies]
 proc-macro2 = "1.0"
 quote = '1.0'
-syn = { version = '2.0', features = ['visit', 'full'] }
+syn = { version = '2.0', features = ['visit', 'visit-mut', 'full'] }
 wasm-bindgen-backend = { path = "../backend", version = "=0.2.93" }
 wasm-bindgen-shared = { path = "../shared", version = "=0.2.93" }

crates/macro-support/src/parser.rs

@@ -11,6 +11,7 @@ use quote::ToTokens;
 use syn::ext::IdentExt;
 use syn::parse::{Parse, ParseStream, Result as SynResult};
 use syn::spanned::Spanned;
+use syn::visit_mut::VisitMut;
 use syn::{ItemFn, Lit, MacroDelimiter, ReturnType};
 
 use crate::ClassMarker;
@@ -884,6 +885,15 @@ pub(crate) fn is_js_keyword(keyword: &str, skip: Option<&[&str]>) -> bool {
         .any(|this| *this == keyword)
 }
 
+struct SelfReplace(Ident);
+impl VisitMut for SelfReplace {
+    fn visit_ident_mut(&mut self, i: &mut proc_macro2::Ident) {
+        if i == "Self" {
+            *i = self.0.clone();
+        }
+    }
+}
+
 /// Construct a function (and gets the self type if appropriate) for our AST from a syn function.
 #[allow(clippy::too_many_arguments)]
 fn function_from_decl(
@@ -911,24 +921,14 @@ fn function_from_decl(
 
     let syn::Signature { inputs, output, .. } = sig;
 
-    let replace_self = |t: syn::Type| {
+    let replace_self = |mut t: syn::Type| {
         let self_ty = match self_ty {
             Some(i) => i,
             None => return t,
         };
-        let path = match get_ty(&t) {
-            syn::Type::Path(syn::TypePath { qself: None, path }) => path.clone(),
-            other => return other.clone(),
-        };
-        let new_path = if path.segments.len() == 1 && path.segments[0].ident == "Self" {
-            self_ty.clone().into()
-        } else {
-            path
-        };
-        syn::Type::Path(syn::TypePath {
-            qself: None,
-            path: new_path,
-        })
+        let mut replace = SelfReplace(self_ty.clone());
+        replace.visit_type_mut(&mut t);
+        t
     };
 
     let replace_colliding_arg = |i: &mut syn::PatType| {

tests/wasm/inner_self.rs

@@ -0,0 +1,28 @@
+//! This tests that the `wasm_bindgen` macro produces code that compiles for these use cases.
+//! `cargo test --target wasm32-unknown-unknown` will not run if any of these tests breaks.
+use wasm_bindgen::prelude::*;
+
+#[wasm_bindgen]
+pub struct A;
+
+#[wasm_bindgen]
+pub struct SelfPortrait;
+
+#[wasm_bindgen]
+impl A {
+    pub fn test_only_self() -> Self {
+        A
+    }
+    pub fn test_option_self() -> Option<Self> {
+        None
+    }
+    pub fn test_nested_self() -> Result<Option<Self>, String> {
+        Ok(None)
+    }
+    pub fn test_self_slice() -> Box<[Self]> {
+        Box::new([])
+    }
+    pub fn test_selfish() -> Result<Self, SelfPortrait> {
+        Ok(A)
+    }
+}

tests/wasm/main.rs

@@ -36,6 +36,7 @@ pub mod getters_and_setters;
 pub mod ignore;
 pub mod import_class;
 pub mod imports;
+pub mod inner_self;
 pub mod intrinsics;
 pub mod js_keywords;
 pub mod js_objects;