Create the web-sys crate mechanically from WebIDL (#409)

* Create a new `web-sys` crate

This will eventually contain all the WebIDL-generated bindings to Web APIs.

* ci: Test the new `web-sys` crate in CI

* web-sys: Add a small README

* web-sys: Vendor all the WebIDL files from mozilla-central

* backend: Add a pass to remove AST items that use undefined imports

This is necessary for the WebIDL frontend, which can't translate many WebIDL
constructs into equivalent wasm-bindgen AST things yet. It lets us make
incremental progress: we can generate bindings to methods we can support right
now even though there might be methods on the same interface that we can't
support yet.

* webidl: Add a bunch of missing semicolons

* webidl: Make parsing private

It was only `pub` so that we could test it, but we ended up moving towards
integration tests rather than unit tests that assert particular ASTs are parsed
from WebIDL files.

* webidl: Remove uses of undefined import types

* test-project-builder: Build projects in "very verbose" mode

This helps for debugging failing WebIDL-related tests.

* test-project-builder: Add more profiling timers

* test-project-builder: Detect when webpack-dev-server fails

Instead of going into an infinite loop, detect when webpack-dev-server fails to
start up and early exit the test.

* webidl: Specify version for dev-dependency on wasm-bindgen-backend

Instead of only a relative path.

* guide: Add section about contributing to `web-sys`

* WIP enable Event.webidl

Still need to fix and finish the test.

* Update expected webidl output

* Start out a test's status as incomplete

That way if we don't fill it in the error message doesn't look quite so bizarre

* Fix onerror function in headless mode

Otherwise we don't see any output!

* Fix package.json/node_modules handling in project generation

Make sure these are looked up in the git project root rather than the crate root

* Avoid logging body text

This was meant for debugging and is otherwise pretty noisy

* Fix a relative path

* More expected test fixes

* Fix a typo

* test-project-builder: Allow asynchronous tests

* webidl: Convert [Unforgeable] attributes into `#[wasm_bindgen(structural)]`

Fixes #432

* test-project-builder: Print generated WebIDL bindings for debugging purposes

Helps debug bad WebIDL bindings generation inside tests.

* When we can't find a descriptor, say which one can't be found

This helps when debugging things that need to become structural.

* web-sys: Test bindings for Event

* ci: Use `--manifest-path dir` instead of `cd dir && ...`

* web-sys: Just move .webidl files isntead of symlinking to enable them

* tests: Polyfill Array.prototype.values for older browsers in CI

* test-project-builder: Don't panic on poisoned headless test mutex

We only use it to serialize headless tests so that we don't try to bind the port
concurrently. Its OK to run another headless test if an earlier one panicked.

* JsValue: Add {is,as}_{object,function} methods

Allows dynamically casting values to `js::Object` and `js::Function`.

* tidy: Fix whitespace and missing semicolons

* Allow for dynamic feature detection of methods

If we create bindings to a method that doesn't exist in this implementation,
then it shouldn't fail until if/when we actually try and invoke that missing
method.

* tests: Do feature detection in Array.prototype.values test

* Add JsValue::{is_string, as_js_string} methods

And document all the cast/convert/check methods for js value.

* eslint: allow backtick string literals

* Only generate a fallback import function for non-structural imports

Author: fitzgen

.eslintrc

@@ -18,7 +18,8 @@
         ],
     "quotes": [
         "error",
-        "single"
+        "single",
+        { "allowTemplateLiterals": true }
     ],
     "semi": [
         "error",

.travis.yml

@@ -60,6 +60,16 @@ matrix:
              ./build.sh) || exit 1;
           done
 
+    # The `web-sys` crate's tests pass on nightly.
+    - rust: nightly
+      env: JOB=test-web-sys
+      before_install: *INSTALL_NODE_VIA_NVM
+      install:
+        - npm install
+      script: cargo test --manifest-path crates/web-sys/Cargo.toml
+      addons:
+        firefox: latest
+
     # Tests pass on nightly using yarn
     - rust: nightly
       env: JOB=test-yarn-smoke

Cargo.toml

@@ -40,6 +40,7 @@ members = [
   "crates/cli",
   "crates/typescript",
   "crates/webidl",
+  "crates/web-sys",
   "examples/hello_world",
   "examples/smorgasboard",
   "examples/console_log",

crates/backend/src/defined.rs

@@ -0,0 +1,256 @@
+use ast;
+use proc_macro2::Ident;
+use syn;
+
+#[derive(Debug, Clone, Copy, PartialEq, Eq)]
+pub enum ImportedTypeKind {
+    /// The definition of an imported type.
+    Definition,
+    /// A reference to an imported type.
+    Reference,
+}
+
+/// Iterate over definitions of and references to imported types in the AST.
+pub trait ImportedTypes {
+    fn imported_types<F>(&self, f: &mut F)
+    where
+        F: FnMut(&Ident, ImportedTypeKind);
+}
+
+/// Iterate over definitions of imported types in the AST.
+pub trait ImportedTypeDefinitions {
+    fn imported_type_definitions<F>(&self, f: &mut F)
+    where
+        F: FnMut(&Ident);
+}
+
+impl<T> ImportedTypeDefinitions for T
+where
+    T: ImportedTypes,
+{
+    fn imported_type_definitions<F>(&self, f: &mut F)
+    where
+        F: FnMut(&Ident),
+    {
+        self.imported_types(&mut |id, kind| {
+            if let ImportedTypeKind::Definition = kind {
+                f(id);
+            }
+        });
+    }
+}
+
+/// Iterate over references to imported types in the AST.
+pub trait ImportedTypeReferences {
+    fn imported_type_references<F>(&self, f: &mut F)
+    where
+        F: FnMut(&Ident);
+}
+
+impl<T> ImportedTypeReferences for T
+where
+    T: ImportedTypes,
+{
+    fn imported_type_references<F>(&self, f: &mut F)
+    where
+        F: FnMut(&Ident),
+    {
+        self.imported_types(&mut |id, kind| {
+            if let ImportedTypeKind::Reference = kind {
+                f(id);
+            }
+        });
+    }
+}
+
+impl ImportedTypes for ast::Program {
+    fn imported_types<F>(&self, f: &mut F)
+    where
+        F: FnMut(&Ident, ImportedTypeKind),
+    {
+        self.imports.imported_types(f);
+        self.type_aliases.imported_types(f);
+    }
+}
+
+impl<T> ImportedTypes for Vec<T>
+where
+    T: ImportedTypes,
+{
+    fn imported_types<F>(&self, f: &mut F)
+    where
+        F: FnMut(&Ident, ImportedTypeKind),
+    {
+        for x in self {
+            x.imported_types(f);
+        }
+    }
+}
+
+impl ImportedTypes for ast::Import {
+    fn imported_types<F>(&self, f: &mut F)
+    where
+        F: FnMut(&Ident, ImportedTypeKind),
+    {
+        self.kind.imported_types(f)
+    }
+}
+
+impl ImportedTypes for ast::ImportKind {
+    fn imported_types<F>(&self, f: &mut F)
+    where
+        F: FnMut(&Ident, ImportedTypeKind),
+    {
+        match self {
+            ast::ImportKind::Static(s) => s.imported_types(f),
+            ast::ImportKind::Function(fun) => fun.imported_types(f),
+            ast::ImportKind::Type(ty) => ty.imported_types(f),
+        }
+    }
+}
+
+impl ImportedTypes for ast::ImportStatic {
+    fn imported_types<F>(&self, f: &mut F)
+    where
+        F: FnMut(&Ident, ImportedTypeKind),
+    {
+        self.ty.imported_types(f);
+    }
+}
+
+impl ImportedTypes for syn::Type {
+    fn imported_types<F>(&self, f: &mut F)
+    where
+        F: FnMut(&Ident, ImportedTypeKind),
+    {
+        match self {
+            syn::Type::Reference(ref r) => r.imported_types(f),
+            syn::Type::Path(ref p) => p.imported_types(f),
+            _ => {}
+        }
+    }
+}
+
+impl ImportedTypes for syn::TypeReference {
+    fn imported_types<F>(&self, f: &mut F)
+    where
+        F: FnMut(&Ident, ImportedTypeKind),
+    {
+        self.elem.imported_types(f);
+    }
+}
+
+impl ImportedTypes for syn::TypePath {
+    fn imported_types<F>(&self, f: &mut F)
+    where
+        F: FnMut(&Ident, ImportedTypeKind),
+    {
+        if self.qself.is_some()
+            || self.path.leading_colon.is_some()
+            || self.path.segments.len() != 1
+        {
+            return;
+        }
+        f(
+            &self.path.segments.last().unwrap().value().ident,
+            ImportedTypeKind::Reference,
+        );
+    }
+}
+
+impl ImportedTypes for ast::ImportFunction {
+    fn imported_types<F>(&self, f: &mut F)
+    where
+        F: FnMut(&Ident, ImportedTypeKind),
+    {
+        self.function.imported_types(f);
+        self.kind.imported_types(f);
+    }
+}
+
+impl ImportedTypes for ast::ImportFunctionKind {
+    fn imported_types<F>(&self, f: &mut F)
+    where
+        F: FnMut(&Ident, ImportedTypeKind),
+    {
+        match self {
+            ast::ImportFunctionKind::Method { ty, .. } => ty.imported_types(f),
+            ast::ImportFunctionKind::Normal => {}
+        }
+    }
+}
+
+impl ImportedTypes for ast::Function {
+    fn imported_types<F>(&self, f: &mut F)
+    where
+        F: FnMut(&Ident, ImportedTypeKind),
+    {
+        self.arguments.imported_types(f);
+        if let Some(ref r) = self.ret {
+            r.imported_types(f);
+        }
+    }
+}
+
+impl ImportedTypes for syn::ArgCaptured {
+    fn imported_types<F>(&self, f: &mut F)
+    where
+        F: FnMut(&Ident, ImportedTypeKind),
+    {
+        self.ty.imported_types(f);
+    }
+}
+
+impl ImportedTypes for ast::ImportType {
+    fn imported_types<F>(&self, f: &mut F)
+    where
+        F: FnMut(&Ident, ImportedTypeKind),
+    {
+        f(&self.name, ImportedTypeKind::Definition);
+    }
+}
+
+impl ImportedTypes for ast::TypeAlias {
+    fn imported_types<F>(&self, f: &mut F)
+    where
+        F: FnMut(&Ident, ImportedTypeKind),
+    {
+        f(&self.dest, ImportedTypeKind::Reference);
+    }
+}
+
+/// Remove any methods, statics, &c, that reference types that are *not*
+/// defined.
+pub trait RemoveUndefinedImports {
+    fn remove_undefined_imports<F>(&mut self, is_defined: &F)
+    where
+        F: Fn(&Ident) -> bool;
+}
+
+impl RemoveUndefinedImports for ast::Program {
+    fn remove_undefined_imports<F>(&mut self, is_defined: &F)
+    where
+        F: Fn(&Ident) -> bool,
+    {
+        self.imports.remove_undefined_imports(is_defined);
+        self.type_aliases.remove_undefined_imports(is_defined);
+    }
+}
+
+impl<T> RemoveUndefinedImports for Vec<T>
+where
+    T: ImportedTypeReferences,
+{
+    fn remove_undefined_imports<F>(&mut self, is_defined: &F)
+    where
+        F: Fn(&Ident) -> bool,
+    {
+        self.retain(|x| {
+            let mut all_defined = true;
+            x.imported_type_references(&mut |id| {
+                all_defined = all_defined && is_defined(id);
+            });
+            all_defined
+        });
+    }
+}

crates/backend/src/lib.rs

@@ -11,4 +11,5 @@ extern crate wasm_bindgen_shared as shared;
 
 pub mod ast;
 mod codegen;
+pub mod defined;
 pub mod util;

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

@@ -284,6 +284,40 @@ impl<'a> Context<'a> {
             ))
         })?;
 
+        self.bind("__wbindgen_is_object", &|me| {
+            me.expose_get_object();
+            Ok(String::from(
+                "
+                function(i) {
+                    const val = getObject(i);
+                    return typeof(val) === 'object' && val !== null ? 1 : 0;
+                }
+                ",
+            ))
+        })?;
+
+        self.bind("__wbindgen_is_function", &|me| {
+            me.expose_get_object();
+            Ok(String::from(
+                "
+                function(i) {
+                    return typeof(getObject(i)) === 'function' ? 1 : 0;
+                }
+                ",
+            ))
+        })?;
+
+        self.bind("__wbindgen_is_string", &|me| {
+            me.expose_get_object();
+            Ok(String::from(
+                "
+                function(i) {
+                    return typeof(getObject(i)) === 'string' ? 1 : 0;
+                }
+                ",
+            ))
+        })?;
+
         self.bind("__wbindgen_string_get", &|me| {
             me.expose_pass_string_to_wasm()?;
             me.expose_get_object();
@@ -1501,7 +1535,7 @@ impl<'a> Context<'a> {
                 if (desc) return desc;
                 obj = Object.getPrototypeOf(obj);
               }
-              throw new Error('descriptor not found');
+              throw new Error(`descriptor for id='${id}' not found`);
             }
             ",
         );
@@ -1866,11 +1900,24 @@ impl<'a, 'b> SubContext<'a, 'b> {
                             }
                         };
 
+                        let fallback = if import.structural {
+                            "".to_string()
+                        } else {
+                            format!(
+                                " || function() {{
+                                    throw new Error(`wasm-bindgen: {} does not exist`);
+                                }}",
+                                target
+                            )
+                        };
+
                         self.cx.global(&format!(
                             "
-                            const {}_target = {};
+                            const {}_target = {} {} ;
                             ",
-                            import.shim, target
+                            import.shim,
+                            target,
+                            fallback
                         ));
                         format!(
                             "{}_target{}",