Support by-value self methods (#348)

Refactor slightly to use the same internal support that the other reference
conversions are using.

Closes #329

crates/backend/src/ast.rs

@@ -17,13 +17,19 @@ pub struct Program {
 #[cfg_attr(feature = "extra-traits", derive(Debug, PartialEq, Eq))]
 pub struct Export {
     pub class: Option<Ident>,
-    pub method: bool,
-    pub mutable: bool,
+    pub method_self: Option<MethodSelf>,
     pub constructor: Option<String>,
     pub function: Function,
     pub comments: Vec<String>,
 }
 
+#[cfg_attr(feature = "extra-traits", derive(Debug, PartialEq, Eq))]
+pub enum MethodSelf {
+    ByValue,
+    RefMutable,
+    RefShared,
+}
+
 #[cfg_attr(feature = "extra-traits", derive(Debug, PartialEq, Eq))]
 pub struct Import {
     pub module: Option<String>,
@@ -170,8 +176,7 @@ impl Program {
                 f.to_tokens(tokens);
                 self.exports.push(Export {
                     class: None,
-                    method: false,
-                    mutable: false,
+                    method_self: None,
                     constructor: None,
                     function: Function::from(f, opts),
                     comments,
@@ -263,7 +268,7 @@ impl Program {
             None
         };
 
-        let (function, mutable) = Function::from_decl(
+        let (function, method_self) = Function::from_decl(
             &method.sig.ident,
             Box::new(method.sig.decl.clone()),
             method.attrs.clone(),
@@ -274,8 +279,7 @@ impl Program {
 
         self.exports.push(Export {
             class: Some(class.clone()),
-            method: mutable.is_some(),
-            mutable: mutable.unwrap_or(false),
+            method_self,
             constructor,
             function,
             comments,
@@ -529,7 +533,7 @@ impl Function {
         opts: BindgenAttrs,
         vis: syn::Visibility,
         allow_self: bool,
-    ) -> (Function, Option<bool>) {
+    ) -> (Function, Option<MethodSelf>) {
         if decl.variadic.is_some() {
             panic!("can't bindgen variadic functions")
         }
@@ -541,17 +545,23 @@ impl Function {
 
         let syn::FnDecl { inputs, output, .. } = { *decl };
 
-        let mut mutable = None;
+        let mut method_self = None;
         let arguments = inputs
             .into_iter()
             .filter_map(|arg| match arg {
                 syn::FnArg::Captured(c) => Some(c),
                 syn::FnArg::SelfValue(_) => {
-                    panic!("by-value `self` not yet supported");
+                    assert!(method_self.is_none());
+                    method_self = Some(MethodSelf::ByValue);
+                    None
                 }
                 syn::FnArg::SelfRef(ref a) if allow_self => {
-                    assert!(mutable.is_none());
-                    mutable = Some(a.mutability.is_some());
+                    assert!(method_self.is_none());
+                    if a.mutability.is_some() {
+                        method_self = Some(MethodSelf::RefMutable);
+                    } else {
+                        method_self = Some(MethodSelf::RefShared);
+                    }
                     None
                 }
                 _ => panic!("arguments cannot be `self` or ignored"),
@@ -572,7 +582,7 @@ impl Function {
                 rust_vis: vis,
                 rust_attrs: attrs,
             },
-            mutable,
+            method_self,
         )
     }
 
@@ -618,9 +628,15 @@ impl Export {
     }
 
     fn shared(&self) -> shared::Export {
+        let (method, consumed) = match self.method_self {
+            Some(MethodSelf::ByValue) => (true, true),
+            Some(_) => (true, false),
+            None => (false, false),
+        };
         shared::Export {
             class: self.class.as_ref().map(|s| s.to_string()),
-            method: self.method,
+            method,
+            consumed,
             constructor: self.constructor.clone(),
             function: self.function.shared(),
             comments: self.comments.clone(),

crates/backend/src/codegen.rs

@@ -309,16 +309,61 @@ impl ToTokens for ast::Export {
         let ret = Ident::new("_ret", Span::call_site());
 
         let mut offset = 0;
-        if self.method {
-            let class = self.class.as_ref().unwrap();
-            args.push(quote! { me: *mut ::wasm_bindgen::__rt::WasmRefCell<#class> });
-            arg_conversions.push(quote! {
-                ::wasm_bindgen::__rt::assert_not_null(me);
-                let me = unsafe { &*me };
-            });
+        if self.method_self.is_some() {
+            args.push(quote! { me: u32 });
             offset = 1;
         }
 
+        let name = &self.function.name;
+        let receiver = match self.method_self {
+            Some(ast::MethodSelf::ByValue) => {
+                let class = self.class.as_ref().unwrap();
+                arg_conversions.push(quote! {
+                    let me = unsafe {
+                        <#class as ::wasm_bindgen::convert::FromWasmAbi>::from_abi(
+                            me,
+                            &mut ::wasm_bindgen::convert::GlobalStack::new(),
+                        )
+                    };
+                });
+                quote! { me.#name }
+            }
+            Some(ast::MethodSelf::RefMutable) => {
+                let class = self.class.as_ref().unwrap();
+                arg_conversions.push(quote! {
+                    let mut me = unsafe {
+                        <#class as ::wasm_bindgen::convert::RefMutFromWasmAbi>
+                            ::ref_mut_from_abi(
+                                me,
+                                &mut ::wasm_bindgen::convert::GlobalStack::new(),
+                            )
+                    };
+                    let me = &mut *me;
+                });
+                quote! { me.#name }
+            }
+            Some(ast::MethodSelf::RefShared) => {
+                let class = self.class.as_ref().unwrap();
+                arg_conversions.push(quote! {
+                    let me = unsafe {
+                        <#class as ::wasm_bindgen::convert::RefFromWasmAbi>
+                            ::ref_from_abi(
+                                me,
+                                &mut ::wasm_bindgen::convert::GlobalStack::new(),
+                            )
+                    };
+                    let me = &*me;
+                });
+                quote! { me.#name }
+            }
+            None => {
+                match &self.class {
+                    Some(class) => quote! { #class::#name },
+                    None => quote! { #name }
+                }
+            }
+        };
+
         for (i, syn::ArgCaptured { ty, .. }) in self.function.arguments.iter().enumerate() {
             let i = i + offset;
             let ident = Ident::new(&format!("arg{}", i), Span::call_site());
@@ -394,19 +439,6 @@ impl ToTokens for ast::Export {
             }
             None => quote! { inform(0); },
         };
-
-        let name = &self.function.name;
-        let receiver = match &self.class {
-            Some(_) if self.method => {
-                if self.mutable {
-                    quote! { me.borrow_mut().#name }
-                } else {
-                    quote! { me.borrow().#name }
-                }
-            }
-            Some(class) => quote! { #class::#name },
-            None => quote!{ #name },
-        };
         let descriptor_name = format!("__wbindgen_describe_{}", export_name);
         let descriptor_name = Ident::new(&descriptor_name, Span::call_site());
         let nargs = self.function.arguments.len() as u32;

crates/cli-support/src/js/js2rust.rs

@@ -66,14 +66,22 @@ impl<'a, 'b> Js2Rust<'a, 'b> {
 
     /// Flag this shim as a method call into Rust, so the first Rust argument
     /// passed should be `this.ptr`.
-    pub fn method(&mut self, method: bool) -> &mut Self {
+    pub fn method(&mut self, method: bool, consumed: bool) -> &mut Self {
         if method {
             self.prelude(
                 "if (this.ptr === 0) {
-                throw new Error('Attempt to use a moved value');
-            }",
+                    throw new Error('Attempt to use a moved value');
+                }"
             );
-            self.rust_arguments.insert(0, "this.ptr".to_string());
+            if consumed {
+                self.prelude("\
+                    const ptr = this.ptr;\n\
+                    this.ptr = 0;\n\
+                ");
+                self.rust_arguments.insert(0, "ptr".to_string());
+            } else {
+                self.rust_arguments.insert(0, "this.ptr".to_string());
+            }
         }
         self
     }

crates/cli-support/src/js/mod.rs

@@ -551,7 +551,7 @@ impl<'a> Context<'a> {
 
             let set = {
                 let mut cx = Js2Rust::new(&field.name, self);
-                cx.method(true).argument(&descriptor)?.ret(&None)?;
+                cx.method(true, false).argument(&descriptor)?.ret(&None)?;
                 ts_dst.push_str(&format!(
                     "{}{}: {}\n",
                     if field.readonly { "readonly " } else { "" },
@@ -561,7 +561,7 @@ impl<'a> Context<'a> {
                 cx.finish("", &format!("wasm.{}", wasm_setter)).0
             };
             let (get, _ts) = Js2Rust::new(&field.name, self)
-                .method(true)
+                .method(true, false)
                 .ret(&Some(descriptor))?
                 .finish("", &format!("wasm.{}", wasm_getter));
             if !dst.ends_with("\n") {
@@ -1657,7 +1657,7 @@ impl<'a, 'b> SubContext<'a, 'b> {
         };
 
         let (js, ts) = Js2Rust::new(&export.function.name, self.cx)
-            .method(export.method)
+            .method(export.method, export.consumed)
             .process(descriptor.unwrap_function())?
             .finish("", &format!("wasm.{}", wasm_name));
         let class = self

crates/shared/src/lib.rs

@@ -1,7 +1,7 @@
 #[macro_use]
 extern crate serde_derive;
 
-pub const SCHEMA_VERSION: &str = "4";
+pub const SCHEMA_VERSION: &str = "5";
 
 #[derive(Deserialize)]
 pub struct ProgramOnlySchema {
@@ -72,6 +72,7 @@ pub struct ImportType {}
 pub struct Export {
     pub class: Option<String>,
     pub method: bool,
+    pub consumed: bool,
     pub constructor: Option<String>,
     pub function: Function,
     pub comments: Vec<String>,

tests/all/classes.rs

@@ -32,6 +32,10 @@ fn simple() {
                     self.contents += amt;
                     self.contents
                 }
+
+                pub fn consume(self) -> u32 {
+                    self.contents
+                }
             }
         "#,
         )
@@ -46,7 +50,9 @@ fn simple() {
                 assert.strictEqual(r.add(0), 0);
                 assert.strictEqual(r.add(1), 1);
                 assert.strictEqual(r.add(1), 2);
-                r.free();
+                r.add(2);
+                assert.strictEqual(r.consume(), 4);
+                assert.throws(() => r.free(), /null pointer passed to rust/);
 
                 const r2 = Foo.with_contents(10);
                 assert.strictEqual(r2.add(1), 11);
@@ -672,3 +678,40 @@ fn readonly_fields() {
         )
         .test();
 }
+
+#[test]
+fn double_consume() {
+    project()
+        .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 {
+                #[wasm_bindgen(constructor)]
+                pub fn new() -> Foo {
+                    Foo {}
+                }
+
+                pub fn consume(self, other: Foo) {
+                    drop(other);
+                }
+            }
+        "#)
+        .file("test.ts", r#"
+            import * as assert from "assert";
+            import { Foo } from "./out";
+
+            export function test() {
+                const r = Foo.new();
+                assert.throws(() => r.consume(r), /Attempt to use a moved value/);
+            }
+        "#)
+        .test();
+}