Work with #![no_std] contexts

This commit adds support for both `#![no_std]` in the wasm-bindgen runtime
support (disabled by default with an on-by-default `std` feature). This also
adds support to work and compile in the context of `#![no_std]` crates.

Closes #146

Cargo.toml

@@ -16,6 +16,10 @@ Easy support for interacting between JS and Rust.
 test = false
 doctest = false
 
+[features]
+default = ["std"]
+std = []
+
 [dependencies]
 wasm-bindgen-macro = { path = "crates/macro", version = "=0.2.4" }
 

crates/backend/src/codegen.rs

@@ -116,13 +116,22 @@ impl ToTokens for ast::Struct {
                 }
             }
 
+            ::wasm_bindgen::__wbindgen_if_not_std! {
+                compile_error! {
+                    "exporting a class to JS requires the `std` feature to \
+                     be enabled in the `wasm-bindgen` crate"
+                }
+            }
+
             impl ::wasm_bindgen::convert::IntoWasmAbi for #name {
                 type Abi = u32;
 
                 fn into_abi(self, _extra: &mut ::wasm_bindgen::convert::Stack)
                     -> u32
                 {
-                    Box::into_raw(Box::new(::wasm_bindgen::__rt::WasmRefCell::new(self))) as u32
+                    use wasm_bindgen::__rt::std::boxed::Box;
+                    use wasm_bindgen::__rt::WasmRefCell;
+                    Box::into_raw(Box::new(WasmRefCell::new(self))) as u32
                 }
             }
 
@@ -132,14 +141,49 @@ impl ToTokens for ast::Struct {
                 unsafe fn from_abi(js: u32, _extra: &mut ::wasm_bindgen::convert::Stack)
                     -> Self
                 {
-                    let ptr = js as *mut ::wasm_bindgen::__rt::WasmRefCell<#name>;
+                    use wasm_bindgen::__rt::std::boxed::Box;
-                    ::wasm_bindgen::__rt::assert_not_null(ptr);
+                    use wasm_bindgen::__rt::{assert_not_null, WasmRefCell};
+
+                    let ptr = js as *mut WasmRefCell<#name>;
+                    assert_not_null(ptr);
                     let js = Box::from_raw(ptr);
                     js.borrow_mut(); // make sure no one's borrowing
                     js.into_inner()
                 }
             }
 
+            impl ::wasm_bindgen::__rt::core::convert::From<#name> for
+                ::wasm_bindgen::JsValue
+            {
+                fn from(value: #name) -> Self {
+                    let ptr = ::wasm_bindgen::convert::IntoWasmAbi::into_abi(
+                        value,
+                        unsafe { &mut ::wasm_bindgen::convert::GlobalStack::new() },
+                    );
+
+                    #[wasm_import_module = "__wbindgen_placeholder__"]
+                    extern {
+                        fn #new_fn(ptr: u32) -> u32;
+                    }
+
+                    unsafe {
+                        <::wasm_bindgen::JsValue as ::wasm_bindgen::convert::FromWasmAbi>
+                            ::from_abi(
+                                #new_fn(ptr),
+                                &mut ::wasm_bindgen::convert::GlobalStack::new(),
+                            )
+                    }
+                }
+            }
+
+            #[no_mangle]
+            pub unsafe extern fn #free_fn(ptr: u32) {
+                <#name as ::wasm_bindgen::convert::FromWasmAbi>::from_abi(
+                    ptr,
+                    &mut ::wasm_bindgen::convert::GlobalStack::new(),
+                );
+            }
+
             impl ::wasm_bindgen::convert::RefFromWasmAbi for #name {
                 type Abi = u32;
                 type Anchor = ::wasm_bindgen::__rt::Ref<'static, #name>;
@@ -167,36 +211,6 @@ impl ToTokens for ast::Struct {
                     (*js).borrow_mut()
                 }
             }
-
-            impl ::std::convert::From<#name> for ::wasm_bindgen::JsValue {
-                fn from(value: #name) -> Self {
-                    let ptr = ::wasm_bindgen::convert::IntoWasmAbi::into_abi(
-                        value,
-                        unsafe { &mut ::wasm_bindgen::convert::GlobalStack::new() },
-                    );
-
-                    #[wasm_import_module = "__wbindgen_placeholder__"]
-                    extern {
-                        fn #new_fn(ptr: u32) -> u32;
-                    }
-
-                    unsafe {
-                        <::wasm_bindgen::JsValue as ::wasm_bindgen::convert::FromWasmAbi>
-                            ::from_abi(
-                                #new_fn(ptr),
-                                &mut ::wasm_bindgen::convert::GlobalStack::new(),
-                            )
-                    }
-                }
-            }
-
-            #[no_mangle]
-            pub unsafe extern fn #free_fn(ptr: u32) {
-                <#name as ::wasm_bindgen::convert::FromWasmAbi>::from_abi(
-                    ptr,
-                    &mut ::wasm_bindgen::convert::GlobalStack::new(),
-                );
-            }
         }).to_tokens(tokens);
     }
 }
@@ -419,7 +433,7 @@ impl ToTokens for ast::ImportType {
             impl ::wasm_bindgen::convert::RefFromWasmAbi for #name {
                 type Abi = <::wasm_bindgen::JsValue as
                     ::wasm_bindgen::convert::RefFromWasmAbi>::Abi;
-                type Anchor = ::std::mem::ManuallyDrop<#name>;
+                type Anchor = ::wasm_bindgen::__rt::core::mem::ManuallyDrop<#name>;
 
                 unsafe fn ref_from_abi(
                     js: Self::Abi,
@@ -427,8 +441,8 @@ impl ToTokens for ast::ImportType {
                 ) -> Self::Anchor {
                     let tmp = <::wasm_bindgen::JsValue as ::wasm_bindgen::convert::RefFromWasmAbi>
                         ::ref_from_abi(js, extra);
-                    ::std::mem::ManuallyDrop::new(#name {
+                    ::wasm_bindgen::__rt::core::mem::ManuallyDrop::new(#name {
-                        obj: ::std::mem::ManuallyDrop::into_inner(tmp),
+                        obj: ::wasm_bindgen::__rt::core::mem::ManuallyDrop::into_inner(tmp),
                     })
                 }
             }
@@ -702,7 +716,7 @@ impl ToTokens for ast::ImportStatic {
                     }
                 }
                 ::wasm_bindgen::JsStatic {
-                    __inner: ::std::cell::UnsafeCell::new(None),
+                    __inner: ::wasm_bindgen::__rt::core::cell::UnsafeCell::new(None),
                     __init: init,
                 }
             };

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

@@ -119,9 +119,7 @@ impl<'a, 'b> Js2Rust<'a, 'b> {
                 self.finally(&format!("\
                     wasm.__wbindgen_free(ptr{i}, len{i} * {size});\n\
                 ", i = i, size = kind.size()));
-                self.cx.required_internal_exports.insert(
+                self.cx.require_internal_export("__wbindgen_free");
-                    "__wbindgen_free",
-                );
             }
             self.rust_arguments.push(format!("ptr{}", i));
             return
@@ -216,7 +214,7 @@ impl<'a, 'b> Js2Rust<'a, 'b> {
             self.ret_ty = ty.js_ty().to_string();
             let f = self.cx.expose_get_vector_from_wasm(ty);
             self.cx.expose_get_global_argument();
-            self.cx.required_internal_exports.insert("__wbindgen_free");
+            self.cx.require_internal_export("__wbindgen_free");
             self.ret_expr = format!("\
                 const ret = RET;\n\
                 const len = getGlobalArgument(0);\n\

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

@@ -62,6 +62,22 @@ impl<'a> Context<'a> {
         self.global(&global);
     }
 
+    fn require_internal_export(&mut self, name: &'static str) {
+        if !self.required_internal_exports.insert(name) {
+            return
+        }
+        if let Some(s) = self.module.export_section() {
+            if s.entries().iter().any(|e| e.field() == name) {
+                return
+            }
+        }
+
+        panic!("\n\nthe exported function `{}` is required to generate bindings \
+                but it was not found in the wasm file, perhaps the `std` feature \
+                of the `wasm-bindgen` crate needs to be enabled?\n\n",
+               name);
+    }
+
     pub fn finalize(&mut self, module_name: &str) -> (String, String) {
         self.unexport_unused_internal_exports();
         self.gc();
@@ -642,7 +658,7 @@ impl<'a> Context<'a> {
         if !self.exposed_globals.insert("pass_string_to_wasm") {
             return;
         }
-        self.required_internal_exports.insert("__wbindgen_malloc");
+        self.require_internal_export("__wbindgen_malloc");
         self.expose_text_encoder();
         self.expose_uint8_memory();
         let debug = if self.config.debug {
@@ -668,7 +684,7 @@ impl<'a> Context<'a> {
         if !self.exposed_globals.insert("pass_array8_to_wasm") {
             return;
         }
-        self.required_internal_exports.insert("__wbindgen_malloc");
+        self.require_internal_export("__wbindgen_malloc");
         self.expose_uint8_memory();
         self.global(&format!("
             function passArray8ToWasm(arg) {{
@@ -683,7 +699,7 @@ impl<'a> Context<'a> {
         if !self.exposed_globals.insert("pass_array16_to_wasm") {
             return;
         }
-        self.required_internal_exports.insert("__wbindgen_malloc");
+        self.require_internal_export("__wbindgen_malloc");
         self.expose_uint16_memory();
         self.global(&format!("
             function passArray16ToWasm(arg) {{
@@ -698,7 +714,7 @@ impl<'a> Context<'a> {
         if !self.exposed_globals.insert("pass_array32_to_wasm") {
             return;
         }
-        self.required_internal_exports.insert("__wbindgen_malloc");
+        self.require_internal_export("__wbindgen_malloc");
         self.expose_uint32_memory();
         self.global(&format!("
             function passArray32ToWasm(arg) {{
@@ -713,7 +729,7 @@ impl<'a> Context<'a> {
         if !self.exposed_globals.insert("pass_array_f32_to_wasm") {
             return;
         }
-        self.required_internal_exports.insert("__wbindgen_malloc");
+        self.require_internal_export("__wbindgen_malloc");
         self.global(&format!("
             function passArrayF32ToWasm(arg) {{
                 const ptr = wasm.__wbindgen_malloc(arg.length * 4);
@@ -727,7 +743,7 @@ impl<'a> Context<'a> {
         if !self.exposed_globals.insert("pass_array_f64_to_wasm") {
             return;
         }
-        self.required_internal_exports.insert("__wbindgen_malloc");
+        self.require_internal_export("__wbindgen_malloc");
         self.global(&format!("
             function passArrayF64ToWasm(arg) {{
                 const ptr = wasm.__wbindgen_malloc(arg.length * 8);
@@ -1172,7 +1188,7 @@ impl<'a> Context<'a> {
         if !self.exposed_globals.insert("global_argument_ptr") {
             return;
         }
-        self.required_internal_exports.insert("__wbindgen_global_argument_ptr");
+        self.require_internal_export("__wbindgen_global_argument_ptr");
         self.global("
             let cachedGlobalArgumentPtr = null;
             function globalArgumentPtr() {

crates/cli-support/src/js/rust2js.rs

@@ -91,9 +91,7 @@ impl<'a, 'b> Rust2Js<'a, 'b> {
                 self.prelude(&format!("\
                     wasm.__wbindgen_free(arg{0}, len{0} * {size});\
                 ", i, size = ty.size()));
-                self.cx.required_internal_exports.insert(
+                self.cx.require_internal_export("__wbindgen_free");
-                    "__wbindgen_free"
-                );
             }
             self.js_arguments.push(format!("v{}", i));
             return

src/closure.rs

@@ -7,6 +7,7 @@
 use std::cell::UnsafeCell;
 use std::marker::Unsize;
 use std::mem::{self, ManuallyDrop};
+use std::prelude::v1::*;
 
 use JsValue;
 use convert::*;

src/convert.rs

@@ -1,14 +1,17 @@
 //! This is mostly an internal module, no stability guarantees are provied. Use
 //! at your own risk.
 
-use std::mem::{self, ManuallyDrop};
+use core::mem::{self, ManuallyDrop};
-use std::ops::{Deref, DerefMut};
+use core::ops::{Deref, DerefMut};
-use std::slice;
+use core::slice;
-use std::str;
+use core::str;
 
 use {JsValue, throw};
 use describe::*;
 
+#[cfg(feature = "std")]
+use std::prelude::v1::*;
+
 #[derive(PartialEq, Eq, Copy, Clone)]
 pub struct Descriptor {
     #[doc(hidden)]
@@ -132,6 +135,7 @@ impl<T> FromWasmAbi for *mut T {
 
 macro_rules! vectors {
     ($($t:ident)*) => ($(
+        #[cfg(feature = "std")]
         impl IntoWasmAbi for Box<[$t]> {
             type Abi = u32;
 
@@ -144,6 +148,7 @@ macro_rules! vectors {
             }
         }
 
+        #[cfg(feature = "std")]
         impl FromWasmAbi for Box<[$t]> {
             type Abi = u32;
 
@@ -183,6 +188,7 @@ vectors! {
     u8 i8 u16 i16 u32 i32 f32 f64
 }
 
+if_std! {
     impl<T> IntoWasmAbi for Vec<T> where Box<[T]>: IntoWasmAbi {
         type Abi = <Box<[T]> as IntoWasmAbi>::Abi;
         fn into_abi(self, extra: &mut Stack) -> Self::Abi {
@@ -213,6 +219,7 @@ impl FromWasmAbi for String {
             String::from_utf8_unchecked(<Vec<u8>>::from_abi(js, extra))
         }
     }
+}
 
 impl<'a> IntoWasmAbi for &'a str {
     type Abi = <&'a [u8] as IntoWasmAbi>::Abi;
@@ -265,6 +272,7 @@ impl RefFromWasmAbi for JsValue {
     }
 }
 
+if_std! {
     impl IntoWasmAbi for Box<[JsValue]> {
         type Abi = u32;
 
@@ -286,6 +294,7 @@ impl FromWasmAbi for Box<[JsValue]> {
             Vec::from_raw_parts(ptr, len, len).into_boxed_slice()
         }
     }
+}
 
 pub struct GlobalStack { next: usize }
 

src/describe.rs

@@ -72,7 +72,6 @@ simple! {
     f64 => F64
     bool => BOOLEAN
     str => STRING
-    String => STRING
     JsValue => ANYREF
 }
 
@@ -105,6 +104,13 @@ impl<'a, T: WasmDescribe + ?Sized> WasmDescribe for &'a mut T {
     }
 }
 
+if_std! {
+    use std::prelude::v1::*;
+
+    impl WasmDescribe for String {
+        fn describe() { inform(STRING) }
+    }
+
     impl<T: WasmDescribe> WasmDescribe for Box<[T]> {
         fn describe() {
             inform(VECTOR);
@@ -117,6 +123,7 @@ impl<T> WasmDescribe for Vec<T> where Box<[T]>: WasmDescribe {
             <Box<[T]>>::describe();
         }
     }
+}
 
 fn _cnt<T: WasmDescribe>() -> u32 { 1 }
 

src/lib.rs

@@ -6,15 +6,22 @@
 //! interface.
 
 #![feature(use_extern_macros, wasm_import_module, try_reserve, unsize)]
+#![no_std]
 
 extern crate wasm_bindgen_macro;
 
-use std::cell::UnsafeCell;
+use core::cell::UnsafeCell;
-use std::ops::Deref;
+use core::ops::Deref;
-use std::ptr;
+use core::ptr;
 
 use convert::FromWasmAbi;
 
+macro_rules! if_std {
+    ($($i:item)*) => ($(
+        #[cfg(feature = "std")] $i
+    )*)
+}
+
 /// A module which is typically glob imported from:
 ///
 /// ```
@@ -23,13 +30,21 @@ use convert::FromWasmAbi;
 pub mod prelude {
     pub use wasm_bindgen_macro::wasm_bindgen;
     pub use JsValue;
+
+    if_std! {
         pub use closure::Closure;
     }
+}
 
 pub mod convert;
-pub mod closure;
 pub mod describe;
 
+if_std! {
+    extern crate std;
+    use std::prelude::v1::*;
+    pub mod closure;
+}
+
 /// Representation of an object owned by JS.
 ///
 /// A `JsValue` doesn't actually live in Rust right now but actually in a table
@@ -136,6 +151,7 @@ impl JsValue {
     ///
     /// If this JS value is not an instance of a string or if it's not valid
     /// utf-8 then this returns `None`.
+    #[cfg(feature = "std")]
     pub fn as_string(&self) -> Option<String> {
         unsafe {
             let mut len = 0;
@@ -192,11 +208,13 @@ impl<'a> From<&'a str> for JsValue {
     }
 }
 
+if_std! {
     impl<'a> From<&'a String> for JsValue {
         fn from(s: &'a String) -> JsValue {
             JsValue::from_str(s)
         }
     }
+}
 
 impl From<bool> for JsValue {
     fn from(s: bool) -> JsValue {
@@ -321,9 +339,23 @@ pub fn throw(s: &str) -> ! {
 
 #[doc(hidden)]
 pub mod __rt {
-    use std::cell::{Cell, UnsafeCell};
+    use core::cell::{Cell, UnsafeCell};
-    use std::mem;
+    use core::ops::{Deref, DerefMut};
-    use std::ops::{Deref, DerefMut};
+    pub extern crate core;
+    #[cfg(feature = "std")]
+    pub extern crate std;
+
+    #[macro_export]
+    #[cfg(feature = "std")]
+    macro_rules! __wbindgen_if_not_std {
+        ($($i:item)*) => ()
+    }
+
+    #[macro_export]
+    #[cfg(not(feature = "std"))]
+    macro_rules! __wbindgen_if_not_std {
+        ($($i:item)*) => ($($i)*)
+    }
 
     #[inline]
     pub fn assert_not_null<T>(s: *mut T) {
@@ -457,8 +489,13 @@ pub mod __rt {
                       unsafe aliasing in rust");
     }
 
+    if_std! {
+        use std::prelude::v1::*;
+
         #[no_mangle]
         pub extern fn __wbindgen_malloc(size: usize) -> *mut u8 {
+            use core::mem;
+
             let mut ret = Vec::new();
             if ret.try_reserve_exact(size).is_err() {
                 super::throw("invalid malloc request");
@@ -472,6 +509,7 @@ pub mod __rt {
         pub unsafe extern fn __wbindgen_free(ptr: *mut u8, size: usize) {
             drop(Vec::<u8>::from_raw_parts(ptr, 0, size));
         }
+    }
 
     pub fn link_this_library() {}
 }

tests/all/main.rs

@@ -15,6 +15,7 @@ struct Project {
     files: Vec<(String, String)>,
     debug: bool,
     node: bool,
+    no_std: bool,
 }
 
 fn project() -> Project {
@@ -25,6 +26,7 @@ fn project() -> Project {
     Project {
         debug: true,
         node: false,
+        no_std: false,
         files: vec![
             ("Cargo.toml".to_string(), format!(r#"
                 [package]
@@ -40,8 +42,7 @@ fn project() -> Project {
                 # XXX: It is important that `[dependencies]` is the last section
                 # here, so that `add_local_dependency` functions correctly!
                 [dependencies]
-                wasm-bindgen = {{ path = '{}' }}
+            "#, IDX.with(|x| *x))),
-            "#, IDX.with(|x| *x), dir.display())),
 
             ("Cargo.lock".to_string(), lockfile),
 
@@ -138,6 +139,11 @@ impl Project {
         self
     }
 
+    fn no_std(&mut self, no_std: bool) -> &mut Project {
+        self.no_std = no_std;
+        self
+    }
+
     fn add_local_dependency(&mut self, name: &str, path: &str) -> &mut Project {
         {
             let cargo_toml = self.files
@@ -145,14 +151,28 @@ impl Project {
                 .find(|f| f.0 == "Cargo.toml")
                 .expect("should have Cargo.toml file!");
             cargo_toml.1.push_str(name);
-            cargo_toml.1.push_str(" = { path = \"");
+            cargo_toml.1.push_str(" = { path = '");
             cargo_toml.1.push_str(path);
-            cargo_toml.1.push_str("\" }");
+            cargo_toml.1.push_str("' }\n");
         }
         self
     }
 
     fn test(&mut self) {
+        {
+            let cargo_toml = self.files
+                .iter_mut()
+                .find(|f| f.0 == "Cargo.toml")
+                .expect("should have Cargo.toml file!");
+            cargo_toml.1.push_str("wasm-bindgen = { path = '");
+            cargo_toml.1.push_str(env!("CARGO_MANIFEST_DIR"));
+            if self.no_std {
+                cargo_toml.1.push_str("', default-features = false");
+            } else {
+                cargo_toml.1.push_str("'");
+            }
+            cargo_toml.1.push_str(" }\n");
+        }
         let root = root();
         drop(fs::remove_dir_all(&root));
         for &(ref file, ref contents) in self.files.iter() {

tests/all/simple.rs

@@ -201,3 +201,89 @@ fn other_exports() {
         "#)
         .test();
 }
+
+#[test]
+fn no_std() {
+    project()
+        .no_std(true)
+        .file("src/lib.rs", r#"
+            #![feature(proc_macro, wasm_custom_section, wasm_import_module)]
+            #![no_std]
+            #![allow(dead_code)]
+
+            extern crate wasm_bindgen;
+            extern crate std as _some_other_name;
+
+            use wasm_bindgen::prelude::*;
+
+            #[wasm_bindgen]
+            extern {
+                fn test(a: &str);
+
+                type Js;
+                #[wasm_bindgen(constructor)]
+                fn new() -> Js;
+                #[wasm_bindgen(method)]
+                fn init(this: &Js);
+            }
+
+            #[wasm_bindgen]
+            pub fn foo(_a: u32) {}
+        "#)
+        .file("test.ts", r#"
+            import * as wasm from "./out_bg";
+
+            export function test() {
+                // mostly just testing the project compiles here
+                wasm.foo(1);
+            }
+        "#)
+        .test();
+}
+
+#[test]
+fn no_std_class() {
+    project()
+        .file("src/lib.rs", r#"
+            #![feature(proc_macro, wasm_custom_section, wasm_import_module)]
+            #![no_std]
+            #![allow(dead_code)]
+
+            extern crate wasm_bindgen;
+            extern crate std as _some_other_name;
+
+            use wasm_bindgen::prelude::*;
+
+            #[wasm_bindgen]
+            extern {
+                fn test(a: &str);
+
+                type Js;
+                #[wasm_bindgen(constructor)]
+                fn new() -> Js;
+                #[wasm_bindgen(method, structural)]
+                fn init(this: &Js);
+            }
+
+            #[wasm_bindgen]
+            pub fn foo(_a: u32) {}
+
+            #[wasm_bindgen]
+            pub struct A {}
+
+            #[wasm_bindgen]
+            impl A {
+                pub fn foo(&self) {}
+                pub fn bar(&mut self) {}
+            }
+        "#)
+        .file("test.ts", r#"
+            import * as wasm from "./out_bg";
+
+            export function test() {
+                // mostly just testing the project compiles here
+                wasm.foo(1);
+            }
+        "#)
+        .test();
+}