Fix methods returning Self

Rewrite any instance of `Self` to the name of the class

Closes #137

Author: alexcrichton

crates/backend/Cargo.toml

@@ -14,5 +14,5 @@ Backend code generation of the wasm-bindgen tool
 quote = '0.5'
 proc-macro2 = { version = "0.3", features = ["nightly"] }
 wasm-bindgen-shared = { path = "../shared", version = "=0.2.4" }
-syn = { version = '0.13', features = ['full', 'visit'] }
+syn = { version = '0.13', features = ['full', 'visit-mut'] }
 serde_json = "1.0"

crates/backend/src/ast.rs

@@ -179,12 +179,13 @@ impl Program {
             },
             _ => panic!("unsupported self type in impl"),
         };
-        for mut item in item.items.iter_mut() {
-            self.push_impl_item(name, &mut item);
+        for item in item.items.iter_mut() {
+            self.push_impl_item(name, item);
         }
     }
 
     fn push_impl_item(&mut self, class: syn::Ident, item: &mut syn::ImplItem) {
+        replace_self(class, item);
         let method = match item {
             syn::ImplItem::Const(_) => panic!("const definitions aren't supported"),
             syn::ImplItem::Type(_) => panic!("type definitions in impls aren't supported"),
@@ -458,7 +459,7 @@ impl Function {
 
     pub fn from_decl(
         name: syn::Ident,
-        decl: Box<syn::FnDecl>,
+        mut decl: Box<syn::FnDecl>,
         attrs: Vec<syn::Attribute>,
         opts: BindgenAttrs,
         vis: syn::Visibility,
@@ -471,7 +472,7 @@ impl Function {
             panic!("can't bindgen functions with lifetime or type parameters")
         }
 
-        assert_no_lifetimes(&decl);
+        assert_no_lifetimes(&mut decl);
 
         let mut mutable = None;
         let arguments = decl.inputs
@@ -928,15 +929,29 @@ fn term<'a>(cursor: syn::buffer::Cursor<'a>, name: &str) -> syn::synom::PResult<
     syn::parse_error()
 }
 
-fn assert_no_lifetimes(decl: &syn::FnDecl) {
+fn assert_no_lifetimes(decl: &mut syn::FnDecl) {
     struct Walk;
 
-    impl<'ast> syn::visit::Visit<'ast> for Walk {
-        fn visit_lifetime(&mut self, _i: &'ast syn::Lifetime) {
+    impl<'ast> syn::visit_mut::VisitMut for Walk {
+        fn visit_lifetime_mut(&mut self, _i: &mut syn::Lifetime) {
             panic!("it is currently not sound to use lifetimes in function \
                     signatures");
         }
     }
 
-    syn::visit::Visit::visit_fn_decl(&mut Walk, decl);
+    syn::visit_mut::VisitMut::visit_fn_decl_mut(&mut Walk, decl);
+}
+
+fn replace_self(name: syn::Ident, item: &mut syn::ImplItem) {
+    struct Walk(syn::Ident);
+
+    impl syn::visit_mut::VisitMut for Walk {
+        fn visit_ident_mut(&mut self, i: &mut syn::Ident) {
+            if i.as_ref() == "Self" {
+                *i = self.0;
+            }
+        }
+    }
+
+    syn::visit_mut::VisitMut::visit_impl_item_mut(&mut Walk(name), item);
 }

tests/all/classes.rs

@@ -526,3 +526,35 @@ fn public_fields() {
         "#)
         .test();
 }
+
+#[test]
+fn using_self() {
+    project()
+        .debug(false)
+        .file("src/lib.rs", r#"
+            #![feature(proc_macro, wasm_custom_section, wasm_import_module)]
+
+            extern crate wasm_bindgen;
+
+            use wasm_bindgen::prelude::*;
+
+            #[wasm_bindgen]
+            pub struct Foo {
+            }
+
+            #[wasm_bindgen]
+            impl Foo {
+                pub fn new() -> Self {
+                    Foo {}
+                }
+            }
+        "#)
+        .file("test.ts", r#"
+            import { Foo } from "./out";
+
+            export function test() {
+                Foo.new().free();
+            }
+        "#)
+        .test();
+}