Merging upstream version 1.70.0+dfsg2.

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

6 files changed, 2030 insertions, 0 deletions

diff --git a/vendor/wasm-bindgen-macro-support/.cargo-checksum.json b/vendor/wasm-bindgen-macro-support/.cargo-checksum.json
new file mode 100644
index 000000000..4c1483db4
--- /dev/null
+++ b/vendor/wasm-bindgen-macro-support/.cargo-checksum.json
@@ -0,0 +1 @@
+{"files":{"Cargo.toml":"d9c4f36a36c6a503ec9be423ad235553671ace63e6bcdee19152b619f74406f5","LICENSE-APACHE":"a60eea817514531668d7e00765731449fe14d059d3249e0bc93b36de45f759f2","LICENSE-MIT":"378f5840b258e2779c39418f3f2d7b2ba96f1c7917dd6be0713f88305dbda397","src/lib.rs":"17788b112497d24d3f2d0e69e1bce4ff225123bc5c1676fadd7f0a7733bc7cc6","src/parser.rs":"1f80d502a8fdaec36d1ad9730ec58781524ae08dba240008eb76d081d3c91e8f"},"package":"07bc0c051dc5f23e307b13285f9d75df86bfdf816c5721e573dec1f9b8aa193c"}
\ No newline at end of file
diff --git a/vendor/wasm-bindgen-macro-support/Cargo.toml b/vendor/wasm-bindgen-macro-support/Cargo.toml
new file mode 100644
index 000000000..378973e81
--- /dev/null
+++ b/vendor/wasm-bindgen-macro-support/Cargo.toml
@@ -0,0 +1,47 @@
+# THIS FILE IS AUTOMATICALLY GENERATED BY CARGO
+#
+# When uploading crates to the registry Cargo will automatically
+# "normalize" Cargo.toml files for maximal compatibility
+# with all versions of Cargo and also rewrite `path` dependencies
+# to registry (e.g., crates.io) dependencies.
+#
+# If you are reading this file be aware that the original Cargo.toml
+# will likely look very different (and much more reasonable).
+# See Cargo.toml.orig for the original contents.
+
+[package]
+edition = "2018"
+name = "wasm-bindgen-macro-support"
+version = "0.2.83"
+authors = ["The wasm-bindgen Developers"]
+description = """
+The part of the implementation of the `#[wasm_bindgen]` attribute that is not in the shared backend crate
+"""
+homepage = "https://rustwasm.github.io/wasm-bindgen/"
+documentation = "https://docs.rs/wasm-bindgen"
+license = "MIT/Apache-2.0"
+repository = "https://github.com/rustwasm/wasm-bindgen/tree/master/crates/macro-support"
+
+[dependencies.proc-macro2]
+version = "1.0"
+
+[dependencies.quote]
+version = "1.0"
+
+[dependencies.syn]
+version = "1.0.67"
+features = [
+    "visit",
+    "full",
+]
+
+[dependencies.wasm-bindgen-backend]
+version = "=0.2.83"
+
+[dependencies.wasm-bindgen-shared]
+version = "=0.2.83"
+
+[features]
+extra-traits = ["syn/extra-traits"]
+spans = ["wasm-bindgen-backend/spans"]
+strict-macro = []
diff --git a/vendor/wasm-bindgen-macro-support/LICENSE-APACHE b/vendor/wasm-bindgen-macro-support/LICENSE-APACHE
new file mode 100644
index 000000000..16fe87b06
--- /dev/null
+++ b/vendor/wasm-bindgen-macro-support/LICENSE-APACHE
@@ -0,0 +1,201 @@
+                              Apache License
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+Unless required by applicable law or agreed to in writing, software
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diff --git a/vendor/wasm-bindgen-macro-support/LICENSE-MIT b/vendor/wasm-bindgen-macro-support/LICENSE-MIT
new file mode 100644
index 000000000..39e0ed660
--- /dev/null
+++ b/vendor/wasm-bindgen-macro-support/LICENSE-MIT
@@ -0,0 +1,25 @@
+Copyright (c) 2014 Alex Crichton
+
+Permission is hereby granted, free of charge, to any
+person obtaining a copy of this software and associated
+documentation files (the "Software"), to deal in the
+Software without restriction, including without
+limitation the rights to use, copy, modify, merge,
+publish, distribute, sublicense, and/or sell copies of
+the Software, and to permit persons to whom the Software
+is furnished to do so, subject to the following
+conditions:
+
+The above copyright notice and this permission notice
+shall be included in all copies or substantial portions
+of the Software.
+
+THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF
+ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED
+TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A
+PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT
+SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY
+CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
+OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR
+IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
+DEALINGS IN THE SOFTWARE.
diff --git a/vendor/wasm-bindgen-macro-support/src/lib.rs b/vendor/wasm-bindgen-macro-support/src/lib.rs
new file mode 100644
index 000000000..b7a35ae1b
--- /dev/null
+++ b/vendor/wasm-bindgen-macro-support/src/lib.rs
@@ -0,0 +1,105 @@
+//! This crate contains the part of the implementation of the `#[wasm_bindgen]` optsibute that is
+//! not in the shared backend crate.
+
+#![doc(html_root_url = "https://docs.rs/wasm-bindgen-macro-support/0.2")]
+
+extern crate proc_macro2;
+extern crate quote;
+#[macro_use]
+extern crate syn;
+#[macro_use]
+extern crate wasm_bindgen_backend as backend;
+extern crate wasm_bindgen_shared as shared;
+
+pub use crate::parser::BindgenAttrs;
+use crate::parser::MacroParse;
+use backend::{Diagnostic, TryToTokens};
+use proc_macro2::TokenStream;
+use quote::ToTokens;
+use quote::TokenStreamExt;
+use syn::parse::{Parse, ParseStream, Result as SynResult};
+
+mod parser;
+
+/// Takes the parsed input from a `#[wasm_bindgen]` macro and returns the generated bindings
+pub fn expand(attr: TokenStream, input: TokenStream) -> Result<TokenStream, Diagnostic> {
+    parser::reset_attrs_used();
+    let item = syn::parse2::<syn::Item>(input)?;
+    let opts = syn::parse2(attr)?;
+
+    let mut tokens = proc_macro2::TokenStream::new();
+    let mut program = backend::ast::Program::default();
+    item.macro_parse(&mut program, (Some(opts), &mut tokens))?;
+    program.try_to_tokens(&mut tokens)?;
+
+    // If we successfully got here then we should have used up all attributes
+    // and considered all of them to see if they were used. If one was forgotten
+    // that's a bug on our end, so sanity check here.
+    parser::check_unused_attrs(&mut tokens);
+
+    Ok(tokens)
+}
+
+/// Takes the parsed input from a `#[wasm_bindgen]` macro and returns the generated bindings
+pub fn expand_class_marker(
+    attr: TokenStream,
+    input: TokenStream,
+) -> Result<TokenStream, Diagnostic> {
+    parser::reset_attrs_used();
+    let mut item = syn::parse2::<syn::ImplItemMethod>(input)?;
+    let opts: ClassMarker = syn::parse2(attr)?;
+
+    let mut program = backend::ast::Program::default();
+    item.macro_parse(&mut program, (&opts.class, &opts.js_class))?;
+
+    // This is where things are slightly different, we are being expanded in the
+    // context of an impl so we can't inject arbitrary item-like tokens into the
+    // output stream. If we were to do that then it wouldn't parse!
+    //
+    // Instead what we want to do is to generate the tokens for `program` into
+    // the header of the function. This'll inject some no_mangle functions and
+    // statics and such, and they should all be valid in the context of the
+    // start of a function.
+    //
+    // We manually implement `ToTokens for ImplItemMethod` here, injecting our
+    // program's tokens before the actual method's inner body tokens.
+    let mut tokens = proc_macro2::TokenStream::new();
+    tokens.append_all(item.attrs.iter().filter(|attr| match attr.style {
+        syn::AttrStyle::Outer => true,
+        _ => false,
+    }));
+    item.vis.to_tokens(&mut tokens);
+    item.sig.to_tokens(&mut tokens);
+    let mut err = None;
+    item.block.brace_token.surround(&mut tokens, |tokens| {
+        if let Err(e) = program.try_to_tokens(tokens) {
+            err = Some(e);
+        }
+        parser::check_unused_attrs(tokens); // same as above
+        tokens.append_all(item.attrs.iter().filter(|attr| match attr.style {
+            syn::AttrStyle::Inner(_) => true,
+            _ => false,
+        }));
+        tokens.append_all(&item.block.stmts);
+    });
+
+    if let Some(err) = err {
+        return Err(err);
+    }
+
+    Ok(tokens)
+}
+
+struct ClassMarker {
+    class: syn::Ident,
+    js_class: String,
+}
+
+impl Parse for ClassMarker {
+    fn parse(input: ParseStream) -> SynResult<Self> {
+        let class = input.parse::<syn::Ident>()?;
+        input.parse::<Token![=]>()?;
+        let js_class = input.parse::<syn::LitStr>()?.value();
+        Ok(ClassMarker { class, js_class })
+    }
+}
diff --git a/vendor/wasm-bindgen-macro-support/src/parser.rs b/vendor/wasm-bindgen-macro-support/src/parser.rs
new file mode 100644
index 000000000..d05f139f6
--- /dev/null
+++ b/vendor/wasm-bindgen-macro-support/src/parser.rs
@@ -0,0 +1,1651 @@
+use std::cell::{Cell, RefCell};
+use std::char;
+use std::str::Chars;
+
+use ast::OperationKind;
+use backend::ast;
+use backend::util::{ident_ty, ShortHash};
+use backend::Diagnostic;
+use proc_macro2::{Delimiter, Ident, Span, TokenStream, TokenTree};
+use quote::ToTokens;
+use syn::parse::{Parse, ParseStream, Result as SynResult};
+use syn::spanned::Spanned;
+use syn::Lit;
+
+thread_local!(static ATTRS: AttributeParseState = Default::default());
+
+/// Javascript keywords which are not keywords in Rust.
+const JS_KEYWORDS: [&str; 20] = [
+    "class",
+    "case",
+    "catch",
+    "debugger",
+    "default",
+    "delete",
+    "export",
+    "extends",
+    "finally",
+    "function",
+    "import",
+    "instanceof",
+    "new",
+    "null",
+    "switch",
+    "this",
+    "throw",
+    "var",
+    "void",
+    "with",
+];
+#[derive(Default)]
+struct AttributeParseState {
+    parsed: Cell<usize>,
+    checks: Cell<usize>,
+    unused_attrs: RefCell<Vec<Ident>>,
+}
+
+/// Parsed attributes from a `#[wasm_bindgen(..)]`.
+#[cfg_attr(feature = "extra-traits", derive(Debug))]
+pub struct BindgenAttrs {
+    /// List of parsed attributes
+    pub attrs: Vec<(Cell<bool>, BindgenAttr)>,
+}
+
+macro_rules! attrgen {
+    ($mac:ident) => {
+        $mac! {
+            (catch, Catch(Span)),
+            (constructor, Constructor(Span)),
+            (method, Method(Span)),
+            (static_method_of, StaticMethodOf(Span, Ident)),
+            (js_namespace, JsNamespace(Span, Vec<String>, Vec<Span>)),
+            (module, Module(Span, String, Span)),
+            (raw_module, RawModule(Span, String, Span)),
+            (inline_js, InlineJs(Span, String, Span)),
+            (getter, Getter(Span, Option<Ident>)),
+            (setter, Setter(Span, Option<Ident>)),
+            (indexing_getter, IndexingGetter(Span)),
+            (indexing_setter, IndexingSetter(Span)),
+            (indexing_deleter, IndexingDeleter(Span)),
+            (structural, Structural(Span)),
+            (r#final, Final(Span)),
+            (readonly, Readonly(Span)),
+            (js_name, JsName(Span, String, Span)),
+            (js_class, JsClass(Span, String, Span)),
+            (inspectable, Inspectable(Span)),
+            (is_type_of, IsTypeOf(Span, syn::Expr)),
+            (extends, Extends(Span, syn::Path)),
+            (no_deref, NoDeref(Span)),
+            (vendor_prefix, VendorPrefix(Span, Ident)),
+            (variadic, Variadic(Span)),
+            (typescript_custom_section, TypescriptCustomSection(Span)),
+            (skip_typescript, SkipTypescript(Span)),
+            (start, Start(Span)),
+            (skip, Skip(Span)),
+            (typescript_type, TypeScriptType(Span, String, Span)),
+            (getter_with_clone, GetterWithClone(Span)),
+
+            // For testing purposes only.
+            (assert_no_shim, AssertNoShim(Span)),
+        }
+    };
+}
+
+macro_rules! methods {
+    ($(($name:ident, $variant:ident($($contents:tt)*)),)*) => {
+        $(methods!(@method $name, $variant($($contents)*));)*
+
+        fn check_used(self) {
+            // Account for the fact this method was called
+            ATTRS.with(|state| {
+                state.checks.set(state.checks.get() + 1);
+
+                state.unused_attrs.borrow_mut().extend(
+                    self.attrs
+                    .iter()
+                    .filter_map(|(used, attr)| if used.get() { None } else { Some(attr) })
+                    .map(|attr| {
+                        match attr {
+                            $(BindgenAttr::$variant(span, ..) => {
+                                syn::parse_quote_spanned!(*span => $name)
+                            })*
+                        }
+                    })
+                );
+            });
+        }
+    };
+
+    (@method $name:ident, $variant:ident(Span, String, Span)) => {
+        fn $name(&self) -> Option<(&str, Span)> {
+            self.attrs
+                .iter()
+                .filter_map(|a| match &a.1 {
+                    BindgenAttr::$variant(_, s, span) => {
+                        a.0.set(true);
+                        Some((&s[..], *span))
+                    }
+                    _ => None,
+                })
+                .next()
+        }
+    };
+
+    (@method $name:ident, $variant:ident(Span, Vec<String>, Vec<Span>)) => {
+        fn $name(&self) -> Option<(&[String], &[Span])> {
+            self.attrs
+                .iter()
+                .filter_map(|a| match &a.1 {
+                    BindgenAttr::$variant(_, ss, spans) => {
+                        a.0.set(true);
+                        Some((&ss[..], &spans[..]))
+                    }
+                    _ => None,
+                })
+                .next()
+        }
+    };
+
+    (@method $name:ident, $variant:ident(Span, $($other:tt)*)) => {
+        #[allow(unused)]
+        fn $name(&self) -> Option<&$($other)*> {
+            self.attrs
+                .iter()
+                .filter_map(|a| match &a.1 {
+                    BindgenAttr::$variant(_, s) => {
+                        a.0.set(true);
+                        Some(s)
+                    }
+                    _ => None,
+                })
+                .next()
+        }
+    };
+
+    (@method $name:ident, $variant:ident($($other:tt)*)) => {
+        #[allow(unused)]
+        fn $name(&self) -> Option<&$($other)*> {
+            self.attrs
+                .iter()
+                .filter_map(|a| match &a.1 {
+                    BindgenAttr::$variant(s) => {
+                        a.0.set(true);
+                        Some(s)
+                    }
+                    _ => None,
+                })
+                .next()
+        }
+    };
+}
+
+impl BindgenAttrs {
+    /// Find and parse the wasm_bindgen attributes.
+    fn find(attrs: &mut Vec<syn::Attribute>) -> Result<BindgenAttrs, Diagnostic> {
+        let mut ret = BindgenAttrs::default();
+        loop {
+            let pos = attrs
+                .iter()
+                .enumerate()
+                .find(|&(_, ref m)| m.path.segments[0].ident == "wasm_bindgen")
+                .map(|a| a.0);
+            let pos = match pos {
+                Some(i) => i,
+                None => return Ok(ret),
+            };
+            let attr = attrs.remove(pos);
+            let mut tts = attr.tokens.clone().into_iter();
+            let group = match tts.next() {
+                Some(TokenTree::Group(d)) => d,
+                Some(_) => bail_span!(attr, "malformed #[wasm_bindgen] attribute"),
+                None => continue,
+            };
+            if tts.next().is_some() {
+                bail_span!(attr, "malformed #[wasm_bindgen] attribute");
+            }
+            if group.delimiter() != Delimiter::Parenthesis {
+                bail_span!(attr, "malformed #[wasm_bindgen] attribute");
+            }
+            let mut attrs: BindgenAttrs = syn::parse2(group.stream())?;
+            ret.attrs.extend(attrs.attrs.drain(..));
+            attrs.check_used();
+        }
+    }
+
+    attrgen!(methods);
+}
+
+impl Default for BindgenAttrs {
+    fn default() -> BindgenAttrs {
+        // Add 1 to the list of parsed attribute sets. We'll use this counter to
+        // sanity check that we call `check_used` an appropriate number of
+        // times.
+        ATTRS.with(|state| state.parsed.set(state.parsed.get() + 1));
+        BindgenAttrs { attrs: Vec::new() }
+    }
+}
+
+impl Parse for BindgenAttrs {
+    fn parse(input: ParseStream) -> SynResult<Self> {
+        let mut attrs = BindgenAttrs::default();
+        if input.is_empty() {
+            return Ok(attrs);
+        }
+
+        let opts = syn::punctuated::Punctuated::<_, syn::token::Comma>::parse_terminated(input)?;
+        attrs.attrs = opts.into_iter().map(|c| (Cell::new(false), c)).collect();
+        Ok(attrs)
+    }
+}
+
+macro_rules! gen_bindgen_attr {
+    ($(($method:ident, $($variants:tt)*),)*) => {
+        /// The possible attributes in the `#[wasm_bindgen]`.
+        #[cfg_attr(feature = "extra-traits", derive(Debug))]
+        pub enum BindgenAttr {
+            $($($variants)*,)*
+        }
+    }
+}
+attrgen!(gen_bindgen_attr);
+
+impl Parse for BindgenAttr {
+    fn parse(input: ParseStream) -> SynResult<Self> {
+        let original = input.fork();
+        let attr: AnyIdent = input.parse()?;
+        let attr = attr.0;
+        let attr_span = attr.span();
+        let attr_string = attr.to_string();
+        let raw_attr_string = format!("r#{}", attr_string);
+
+        macro_rules! parsers {
+            ($(($name:ident, $($contents:tt)*),)*) => {
+                $(
+                    if attr_string == stringify!($name) || raw_attr_string == stringify!($name) {
+                        parsers!(
+                            @parser
+                            $($contents)*
+                        );
+                    }
+                )*
+            };
+
+            (@parser $variant:ident(Span)) => ({
+                return Ok(BindgenAttr::$variant(attr_span));
+            });
+
+            (@parser $variant:ident(Span, Ident)) => ({
+                input.parse::<Token![=]>()?;
+                let ident = input.parse::<AnyIdent>()?.0;
+                return Ok(BindgenAttr::$variant(attr_span, ident))
+            });
+
+            (@parser $variant:ident(Span, Option<Ident>)) => ({
+                if input.parse::<Token![=]>().is_ok() {
+                    let ident = input.parse::<AnyIdent>()?.0;
+                    return Ok(BindgenAttr::$variant(attr_span, Some(ident)))
+                } else {
+                    return Ok(BindgenAttr::$variant(attr_span, None));
+                }
+            });
+
+            (@parser $variant:ident(Span, syn::Path)) => ({
+                input.parse::<Token![=]>()?;
+                return Ok(BindgenAttr::$variant(attr_span, input.parse()?));
+            });
+
+            (@parser $variant:ident(Span, syn::Expr)) => ({
+                input.parse::<Token![=]>()?;
+                return Ok(BindgenAttr::$variant(attr_span, input.parse()?));
+            });
+
+            (@parser $variant:ident(Span, String, Span)) => ({
+                input.parse::<Token![=]>()?;
+                let (val, span) = match input.parse::<syn::LitStr>() {
+                    Ok(str) => (str.value(), str.span()),
+                    Err(_) => {
+                        let ident = input.parse::<AnyIdent>()?.0;
+                        (ident.to_string(), ident.span())
+                    }
+                };
+                return Ok(BindgenAttr::$variant(attr_span, val, span))
+            });
+
+            (@parser $variant:ident(Span, Vec<String>, Vec<Span>)) => ({
+                input.parse::<Token![=]>()?;
+                let (vals, spans) = match input.parse::<syn::ExprArray>() {
+                    Ok(exprs) => {
+                        let mut vals = vec![];
+                        let mut spans = vec![];
+
+                        for expr in exprs.elems.iter() {
+                            if let syn::Expr::Lit(syn::ExprLit {
+                                lit: syn::Lit::Str(ref str),
+                                ..
+                            }) = expr {
+                                vals.push(str.value());
+                                spans.push(str.span());
+                            } else {
+                                return Err(syn::Error::new(expr.span(), "expected string literals"));
+                            }
+                        }
+
+                        (vals, spans)
+                    },
+                    Err(_) => {
+                        let ident = input.parse::<AnyIdent>()?.0;
+                        (vec![ident.to_string()], vec![ident.span()])
+                    }
+                };
+                return Ok(BindgenAttr::$variant(attr_span, vals, spans))
+            });
+        }
+
+        attrgen!(parsers);
+
+        return Err(original.error(if attr_string.starts_with("_") {
+            "unknown attribute: it's safe to remove unused attributes entirely."
+        } else {
+            "unknown attribute"
+        }));
+    }
+}
+
+struct AnyIdent(Ident);
+
+impl Parse for AnyIdent {
+    fn parse(input: ParseStream) -> SynResult<Self> {
+        input.step(|cursor| match cursor.ident() {
+            Some((ident, remaining)) => Ok((AnyIdent(ident), remaining)),
+            None => Err(cursor.error("expected an identifier")),
+        })
+    }
+}
+
+/// Conversion trait with context.
+///
+/// Used to convert syn tokens into an AST, that we can then use to generate glue code. The context
+/// (`Ctx`) is used to pass in the attributes from the `#[wasm_bindgen]`, if needed.
+trait ConvertToAst<Ctx> {
+    /// What we are converting to.
+    type Target;
+    /// Convert into our target.
+    ///
+    /// Since this is used in a procedural macro, use panic to fail.
+    fn convert(self, context: Ctx) -> Result<Self::Target, Diagnostic>;
+}
+
+impl<'a> ConvertToAst<BindgenAttrs> for &'a mut syn::ItemStruct {
+    type Target = ast::Struct;
+
+    fn convert(self, attrs: BindgenAttrs) -> Result<Self::Target, Diagnostic> {
+        if self.generics.params.len() > 0 {
+            bail_span!(
+                self.generics,
+                "structs with #[wasm_bindgen] cannot have lifetime or \
+                 type parameters currently"
+            );
+        }
+        let mut fields = Vec::new();
+        let js_name = attrs
+            .js_name()
+            .map(|s| s.0.to_string())
+            .unwrap_or(self.ident.to_string());
+        let is_inspectable = attrs.inspectable().is_some();
+        let getter_with_clone = attrs.getter_with_clone().is_some();
+        for (i, field) in self.fields.iter_mut().enumerate() {
+            match field.vis {
+                syn::Visibility::Public(..) => {}
+                _ => continue,
+            }
+            let (js_field_name, member) = match &field.ident {
+                Some(ident) => (ident.to_string(), syn::Member::Named(ident.clone())),
+                None => (i.to_string(), syn::Member::Unnamed(i.into())),
+            };
+
+            let attrs = BindgenAttrs::find(&mut field.attrs)?;
+            if attrs.skip().is_some() {
+                attrs.check_used();
+                continue;
+            }
+
+            let js_field_name = match attrs.js_name() {
+                Some((name, _)) => name.to_string(),
+                None => js_field_name,
+            };
+
+            let comments = extract_doc_comments(&field.attrs);
+            let getter = shared::struct_field_get(&js_name, &js_field_name);
+            let setter = shared::struct_field_set(&js_name, &js_field_name);
+
+            fields.push(ast::StructField {
+                rust_name: member,
+                js_name: js_field_name,
+                struct_name: self.ident.clone(),
+                readonly: attrs.readonly().is_some(),
+                ty: field.ty.clone(),
+                getter: Ident::new(&getter, Span::call_site()),
+                setter: Ident::new(&setter, Span::call_site()),
+                comments,
+                generate_typescript: attrs.skip_typescript().is_none(),
+                getter_with_clone: getter_with_clone || attrs.getter_with_clone().is_some(),
+            });
+            attrs.check_used();
+        }
+        let generate_typescript = attrs.skip_typescript().is_none();
+        let comments: Vec<String> = extract_doc_comments(&self.attrs);
+        attrs.check_used();
+        Ok(ast::Struct {
+            rust_name: self.ident.clone(),
+            js_name,
+            fields,
+            comments,
+            is_inspectable,
+            generate_typescript,
+        })
+    }
+}
+
+fn get_ty(mut ty: &syn::Type) -> &syn::Type {
+    while let syn::Type::Group(g) = ty {
+        ty = &g.elem;
+    }
+
+    ty
+}
+
+fn get_expr(mut expr: &syn::Expr) -> &syn::Expr {
+    while let syn::Expr::Group(g) = expr {
+        expr = &g.expr;
+    }
+
+    expr
+}
+
+impl<'a> ConvertToAst<(BindgenAttrs, &'a Option<ast::ImportModule>)> for syn::ForeignItemFn {
+    type Target = ast::ImportKind;
+
+    fn convert(
+        self,
+        (opts, module): (BindgenAttrs, &'a Option<ast::ImportModule>),
+    ) -> Result<Self::Target, Diagnostic> {
+        let mut wasm = function_from_decl(
+            &self.sig.ident,
+            &opts,
+            self.sig.clone(),
+            self.attrs.clone(),
+            self.vis.clone(),
+            false,
+            None,
+            false,
+        )?
+        .0;
+        let catch = opts.catch().is_some();
+        let variadic = opts.variadic().is_some();
+        let js_ret = if catch {
+            // TODO: this assumes a whole bunch:
+            //
+            // * The outer type is actually a `Result`
+            // * The error type is a `JsValue`
+            // * The actual type is the first type parameter
+            //
+            // should probably fix this one day...
+            extract_first_ty_param(wasm.ret.as_ref())?
+        } else {
+            wasm.ret.clone()
+        };
+
+        let operation_kind = operation_kind(&opts);
+
+        let kind = if opts.method().is_some() {
+            let class = wasm.arguments.get(0).ok_or_else(|| {
+                err_span!(self, "imported methods must have at least one argument")
+            })?;
+            let class = match get_ty(&class.ty) {
+                syn::Type::Reference(syn::TypeReference {
+                    mutability: None,
+                    elem,
+                    ..
+                }) => &**elem,
+                _ => bail_span!(
+                    class.ty,
+                    "first argument of method must be a shared reference"
+                ),
+            };
+            let class_name = match get_ty(class) {
+                syn::Type::Path(syn::TypePath {
+                    qself: None,
+                    ref path,
+                }) => path,
+                _ => bail_span!(class, "first argument of method must be a path"),
+            };
+            let class_name = extract_path_ident(class_name)?;
+            let class_name = opts
+                .js_class()
+                .map(|p| p.0.into())
+                .unwrap_or_else(|| class_name.to_string());
+
+            let kind = ast::MethodKind::Operation(ast::Operation {
+                is_static: false,
+                kind: operation_kind,
+            });
+
+            ast::ImportFunctionKind::Method {
+                class: class_name,
+                ty: class.clone(),
+                kind,
+            }
+        } else if let Some(cls) = opts.static_method_of() {
+            let class = opts
+                .js_class()
+                .map(|p| p.0.into())
+                .unwrap_or_else(|| cls.to_string());
+            let ty = ident_ty(cls.clone());
+
+            let kind = ast::MethodKind::Operation(ast::Operation {
+                is_static: true,
+                kind: operation_kind,
+            });
+
+            ast::ImportFunctionKind::Method { class, ty, kind }
+        } else if opts.constructor().is_some() {
+            let class = match js_ret {
+                Some(ref ty) => ty,
+                _ => bail_span!(self, "constructor returns must be bare types"),
+            };
+            let class_name = match get_ty(class) {
+                syn::Type::Path(syn::TypePath {
+                    qself: None,
+                    ref path,
+                }) => path,
+                _ => bail_span!(self, "return value of constructor must be a bare path"),
+            };
+            let class_name = extract_path_ident(class_name)?;
+            let class_name = opts
+                .js_class()
+                .map(|p| p.0.into())
+                .unwrap_or_else(|| class_name.to_string());
+
+            ast::ImportFunctionKind::Method {
+                class: class_name.to_string(),
+                ty: class.clone(),
+                kind: ast::MethodKind::Constructor,
+            }
+        } else {
+            ast::ImportFunctionKind::Normal
+        };
+
+        let shim = {
+            let ns = match kind {
+                ast::ImportFunctionKind::Normal => (0, "n"),
+                ast::ImportFunctionKind::Method { ref class, .. } => (1, &class[..]),
+            };
+            let data = (ns, &self.sig.ident, module);
+            format!(
+                "__wbg_{}_{}",
+                wasm.name
+                    .chars()
+                    .filter(|c| c.is_ascii_alphanumeric())
+                    .collect::<String>(),
+                ShortHash(data)
+            )
+        };
+        if let Some(span) = opts.r#final() {
+            if opts.structural().is_some() {
+                let msg = "cannot specify both `structural` and `final`";
+                return Err(Diagnostic::span_error(*span, msg));
+            }
+        }
+        let assert_no_shim = opts.assert_no_shim().is_some();
+
+        let mut doc_comment = String::new();
+        // Extract the doc comments from our list of attributes.
+        wasm.rust_attrs.retain(|attr| {
+            struct DocContents {
+                contents: String,
+            }
+
+            impl Parse for DocContents {
+                fn parse(input: ParseStream) -> SynResult<Self> {
+                    <Token![=]>::parse(input)?;
+                    match Lit::parse(input)? {
+                        Lit::Str(str) => Ok(Self {
+                            contents: str.value(),
+                        }),
+                        other => Err(syn::Error::new_spanned(other, "expected a string literal")),
+                    }
+                }
+            }
+
+            /// Returns the contents of the passed `#[doc = "..."]` attribute,
+            /// or `None` if it isn't one.
+            fn get_docs(attr: &syn::Attribute) -> Option<String> {
+                if attr.path.is_ident("doc") {
+                    syn::parse2::<DocContents>(attr.tokens.clone())
+                        .ok()
+                        .map(|doc| doc.contents)
+                } else {
+                    None
+                }
+            }
+
+            if let Some(docs) = get_docs(attr) {
+                if !doc_comment.is_empty() {
+                    // Add newlines between the doc comments
+                    doc_comment.push('\n');
+                }
+                // Add this doc comment to the complete docs
+                doc_comment.push_str(&docs);
+
+                // Remove it from the list of regular attributes
+                false
+            } else {
+                true
+            }
+        });
+
+        let ret = ast::ImportKind::Function(ast::ImportFunction {
+            function: wasm,
+            assert_no_shim,
+            kind,
+            js_ret,
+            catch,
+            variadic,
+            structural: opts.structural().is_some() || opts.r#final().is_none(),
+            rust_name: self.sig.ident.clone(),
+            shim: Ident::new(&shim, Span::call_site()),
+            doc_comment,
+        });
+        opts.check_used();
+
+        Ok(ret)
+    }
+}
+
+impl ConvertToAst<BindgenAttrs> for syn::ForeignItemType {
+    type Target = ast::ImportKind;
+
+    fn convert(self, attrs: BindgenAttrs) -> Result<Self::Target, Diagnostic> {
+        let js_name = attrs
+            .js_name()
+            .map(|s| s.0)
+            .map_or_else(|| self.ident.to_string(), |s| s.to_string());
+        let typescript_type = attrs.typescript_type().map(|s| s.0.to_string());
+        let is_type_of = attrs.is_type_of().cloned();
+        let shim = format!("__wbg_instanceof_{}_{}", self.ident, ShortHash(&self.ident));
+        let mut extends = Vec::new();
+        let mut vendor_prefixes = Vec::new();
+        let no_deref = attrs.no_deref().is_some();
+        for (used, attr) in attrs.attrs.iter() {
+            match attr {
+                BindgenAttr::Extends(_, e) => {
+                    extends.push(e.clone());
+                    used.set(true);
+                }
+                BindgenAttr::VendorPrefix(_, e) => {
+                    vendor_prefixes.push(e.clone());
+                    used.set(true);
+                }
+                _ => {}
+            }
+        }
+        attrs.check_used();
+        Ok(ast::ImportKind::Type(ast::ImportType {
+            vis: self.vis,
+            attrs: self.attrs,
+            doc_comment: None,
+            instanceof_shim: shim,
+            is_type_of,
+            rust_name: self.ident,
+            typescript_type,
+            js_name,
+            extends,
+            vendor_prefixes,
+            no_deref,
+        }))
+    }
+}
+
+impl<'a> ConvertToAst<(BindgenAttrs, &'a Option<ast::ImportModule>)> for syn::ForeignItemStatic {
+    type Target = ast::ImportKind;
+
+    fn convert(
+        self,
+        (opts, module): (BindgenAttrs, &'a Option<ast::ImportModule>),
+    ) -> Result<Self::Target, Diagnostic> {
+        if self.mutability.is_some() {
+            bail_span!(self.mutability, "cannot import mutable globals yet")
+        }
+
+        let default_name = self.ident.to_string();
+        let js_name = opts
+            .js_name()
+            .map(|p| p.0)
+            .unwrap_or(&default_name)
+            .to_string();
+        let shim = format!(
+            "__wbg_static_accessor_{}_{}",
+            self.ident,
+            ShortHash((&js_name, module, &self.ident)),
+        );
+        opts.check_used();
+        Ok(ast::ImportKind::Static(ast::ImportStatic {
+            ty: *self.ty,
+            vis: self.vis,
+            rust_name: self.ident.clone(),
+            js_name,
+            shim: Ident::new(&shim, Span::call_site()),
+        }))
+    }
+}
+
+impl ConvertToAst<BindgenAttrs> for syn::ItemFn {
+    type Target = ast::Function;
+
+    fn convert(self, attrs: BindgenAttrs) -> Result<Self::Target, Diagnostic> {
+        match self.vis {
+            syn::Visibility::Public(_) => {}
+            _ => bail_span!(self, "can only #[wasm_bindgen] public functions"),
+        }
+        if self.sig.constness.is_some() {
+            bail_span!(
+                self.sig.constness,
+                "can only #[wasm_bindgen] non-const functions"
+            );
+        }
+
+        let ret = function_from_decl(
+            &self.sig.ident,
+            &attrs,
+            self.sig.clone(),
+            self.attrs,
+            self.vis,
+            false,
+            None,
+            false,
+        )?;
+        attrs.check_used();
+        Ok(ret.0)
+    }
+}
+
+pub(crate) fn is_js_keyword(keyword: &str) -> bool {
+    JS_KEYWORDS.contains(&keyword)
+}
+
+/// 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(
+    decl_name: &syn::Ident,
+    opts: &BindgenAttrs,
+    sig: syn::Signature,
+    attrs: Vec<syn::Attribute>,
+    vis: syn::Visibility,
+    allow_self: bool,
+    self_ty: Option<&Ident>,
+    is_from_impl: bool,
+) -> Result<(ast::Function, Option<ast::MethodSelf>), Diagnostic> {
+    if sig.variadic.is_some() {
+        bail_span!(sig.variadic, "can't #[wasm_bindgen] variadic functions");
+    }
+    if sig.generics.params.len() > 0 {
+        bail_span!(
+            sig.generics,
+            "can't #[wasm_bindgen] functions with lifetime or type parameters",
+        );
+    }
+
+    assert_no_lifetimes(&sig)?;
+
+    let syn::Signature { inputs, output, .. } = sig;
+
+    let replace_self = |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 replace_colliding_arg = |i: &mut syn::PatType| {
+        if let syn::Pat::Ident(ref mut i) = *i.pat {
+            let ident = i.ident.to_string();
+            if is_js_keyword(ident.as_str()) {
+                i.ident = Ident::new(format!("_{}", ident).as_str(), i.ident.span());
+            }
+        }
+    };
+
+    let mut method_self = None;
+    let arguments = inputs
+        .into_iter()
+        .filter_map(|arg| match arg {
+            syn::FnArg::Typed(mut c) => {
+                replace_colliding_arg(&mut c);
+                c.ty = Box::new(replace_self(*c.ty));
+                Some(c)
+            }
+            syn::FnArg::Receiver(r) => {
+                if !allow_self {
+                    panic!("arguments cannot be `self`")
+                }
+                assert!(method_self.is_none());
+                if r.reference.is_none() {
+                    method_self = Some(ast::MethodSelf::ByValue);
+                } else if r.mutability.is_some() {
+                    method_self = Some(ast::MethodSelf::RefMutable);
+                } else {
+                    method_self = Some(ast::MethodSelf::RefShared);
+                }
+                None
+            }
+        })
+        .collect::<Vec<_>>();
+
+    let ret = match output {
+        syn::ReturnType::Default => None,
+        syn::ReturnType::Type(_, ty) => Some(replace_self(*ty)),
+    };
+
+    let (name, name_span, renamed_via_js_name) = if let Some((js_name, js_name_span)) =
+        opts.js_name()
+    {
+        let kind = operation_kind(opts);
+        let prefix = match kind {
+            OperationKind::Setter(_) => "set_",
+            _ => "",
+        };
+        let name = if prefix.is_empty() && opts.method().is_none() && is_js_keyword(js_name) {
+            format!("_{}", js_name)
+        } else {
+            format!("{}{}", prefix, js_name)
+        };
+        (name, js_name_span, true)
+    } else {
+        let name =
+            if !is_from_impl && opts.method().is_none() && is_js_keyword(&decl_name.to_string()) {
+                format!("_{}", decl_name)
+            } else {
+                decl_name.to_string()
+            };
+        (name, decl_name.span(), false)
+    };
+    Ok((
+        ast::Function {
+            arguments,
+            name_span,
+            name,
+            renamed_via_js_name,
+            ret,
+            rust_attrs: attrs,
+            rust_vis: vis,
+            r#async: sig.asyncness.is_some(),
+            generate_typescript: opts.skip_typescript().is_none(),
+            variadic: opts.variadic().is_some(),
+        },
+        method_self,
+    ))
+}
+
+pub(crate) trait MacroParse<Ctx> {
+    /// Parse the contents of an object into our AST, with a context if necessary.
+    ///
+    /// The context is used to have access to the attributes on `#[wasm_bindgen]`, and to allow
+    /// writing to the output `TokenStream`.
+    fn macro_parse(self, program: &mut ast::Program, context: Ctx) -> Result<(), Diagnostic>;
+}
+
+impl<'a> MacroParse<(Option<BindgenAttrs>, &'a mut TokenStream)> for syn::Item {
+    fn macro_parse(
+        self,
+        program: &mut ast::Program,
+        (opts, tokens): (Option<BindgenAttrs>, &'a mut TokenStream),
+    ) -> Result<(), Diagnostic> {
+        match self {
+            syn::Item::Fn(mut f) => {
+                let no_mangle = f
+                    .attrs
+                    .iter()
+                    .enumerate()
+                    .filter_map(|(i, m)| m.parse_meta().ok().map(|m| (i, m)))
+                    .find(|(_, m)| m.path().is_ident("no_mangle"));
+                match no_mangle {
+                    Some((i, _)) => {
+                        f.attrs.remove(i);
+                    }
+                    _ => {}
+                }
+                let comments = extract_doc_comments(&f.attrs);
+                f.to_tokens(tokens);
+                let opts = opts.unwrap_or_default();
+                if opts.start().is_some() {
+                    if f.sig.generics.params.len() > 0 {
+                        bail_span!(&f.sig.generics, "the start function cannot have generics",);
+                    }
+                    if f.sig.inputs.len() > 0 {
+                        bail_span!(&f.sig.inputs, "the start function cannot have arguments",);
+                    }
+                }
+                let method_kind = ast::MethodKind::Operation(ast::Operation {
+                    is_static: true,
+                    kind: operation_kind(&opts),
+                });
+                let rust_name = f.sig.ident.clone();
+                let start = opts.start().is_some();
+                program.exports.push(ast::Export {
+                    comments,
+                    function: f.convert(opts)?,
+                    js_class: None,
+                    method_kind,
+                    method_self: None,
+                    rust_class: None,
+                    rust_name,
+                    start,
+                });
+            }
+            syn::Item::Struct(mut s) => {
+                let opts = opts.unwrap_or_default();
+                program.structs.push((&mut s).convert(opts)?);
+                s.to_tokens(tokens);
+            }
+            syn::Item::Impl(mut i) => {
+                let opts = opts.unwrap_or_default();
+                (&mut i).macro_parse(program, opts)?;
+                i.to_tokens(tokens);
+            }
+            syn::Item::ForeignMod(mut f) => {
+                let opts = match opts {
+                    Some(opts) => opts,
+                    None => BindgenAttrs::find(&mut f.attrs)?,
+                };
+                f.macro_parse(program, opts)?;
+            }
+            syn::Item::Enum(mut e) => {
+                let opts = match opts {
+                    Some(opts) => opts,
+                    None => BindgenAttrs::find(&mut e.attrs)?,
+                };
+                e.macro_parse(program, (tokens, opts))?;
+            }
+            syn::Item::Const(mut c) => {
+                let opts = match opts {
+                    Some(opts) => opts,
+                    None => BindgenAttrs::find(&mut c.attrs)?,
+                };
+                c.macro_parse(program, opts)?;
+            }
+            _ => {
+                bail_span!(
+                    self,
+                    "#[wasm_bindgen] can only be applied to a function, \
+                     struct, enum, impl, or extern block",
+                );
+            }
+        }
+
+        Ok(())
+    }
+}
+
+impl<'a> MacroParse<BindgenAttrs> for &'a mut syn::ItemImpl {
+    fn macro_parse(
+        self,
+        _program: &mut ast::Program,
+        opts: BindgenAttrs,
+    ) -> Result<(), Diagnostic> {
+        if self.defaultness.is_some() {
+            bail_span!(
+                self.defaultness,
+                "#[wasm_bindgen] default impls are not supported"
+            );
+        }
+        if self.unsafety.is_some() {
+            bail_span!(
+                self.unsafety,
+                "#[wasm_bindgen] unsafe impls are not supported"
+            );
+        }
+        if let Some((_, path, _)) = &self.trait_ {
+            bail_span!(path, "#[wasm_bindgen] trait impls are not supported");
+        }
+        if self.generics.params.len() > 0 {
+            bail_span!(
+                self.generics,
+                "#[wasm_bindgen] generic impls aren't supported"
+            );
+        }
+        let name = match get_ty(&self.self_ty) {
+            syn::Type::Path(syn::TypePath {
+                qself: None,
+                ref path,
+            }) => path,
+            _ => bail_span!(
+                self.self_ty,
+                "unsupported self type in #[wasm_bindgen] impl"
+            ),
+        };
+        let mut errors = Vec::new();
+        for item in self.items.iter_mut() {
+            if let Err(e) = prepare_for_impl_recursion(item, &name, &opts) {
+                errors.push(e);
+            }
+        }
+        Diagnostic::from_vec(errors)?;
+        opts.check_used();
+        Ok(())
+    }
+}
+
+// Prepare for recursion into an `impl` block. Here we want to attach an
+// internal attribute, `__wasm_bindgen_class_marker`, with any metadata we need
+// to pass from the impl to the impl item. Recursive macro expansion will then
+// expand the `__wasm_bindgen_class_marker` attribute.
+//
+// Note that we currently do this because inner items may have things like cfgs
+// on them, so we want to expand the impl first, let the insides get cfg'd, and
+// then go for the rest.
+fn prepare_for_impl_recursion(
+    item: &mut syn::ImplItem,
+    class: &syn::Path,
+    impl_opts: &BindgenAttrs,
+) -> Result<(), Diagnostic> {
+    let method = match item {
+        syn::ImplItem::Method(m) => m,
+        syn::ImplItem::Const(_) => {
+            bail_span!(
+                &*item,
+                "const definitions aren't supported with #[wasm_bindgen]"
+            );
+        }
+        syn::ImplItem::Type(_) => bail_span!(
+            &*item,
+            "type definitions in impls aren't supported with #[wasm_bindgen]"
+        ),
+        syn::ImplItem::Macro(_) => {
+            // In theory we want to allow this, but we have no way of expanding
+            // the macro and then placing our magical attributes on the expanded
+            // functions. As a result, just disallow it for now to hopefully
+            // ward off buggy results from this macro.
+            bail_span!(&*item, "macros in impls aren't supported");
+        }
+        syn::ImplItem::Verbatim(_) => panic!("unparsed impl item?"),
+        other => bail_span!(other, "failed to parse this item as a known item"),
+    };
+
+    let ident = extract_path_ident(class)?;
+
+    let js_class = impl_opts
+        .js_class()
+        .map(|s| s.0.to_string())
+        .unwrap_or(ident.to_string());
+
+    method.attrs.insert(
+        0,
+        syn::Attribute {
+            pound_token: Default::default(),
+            style: syn::AttrStyle::Outer,
+            bracket_token: Default::default(),
+            path: syn::parse_quote! { wasm_bindgen::prelude::__wasm_bindgen_class_marker },
+            tokens: quote::quote! { (#class = #js_class) }.into(),
+        },
+    );
+
+    Ok(())
+}
+
+impl<'a, 'b> MacroParse<(&'a Ident, &'a str)> for &'b mut syn::ImplItemMethod {
+    fn macro_parse(
+        self,
+        program: &mut ast::Program,
+        (class, js_class): (&'a Ident, &'a str),
+    ) -> Result<(), Diagnostic> {
+        match self.vis {
+            syn::Visibility::Public(_) => {}
+            _ => return Ok(()),
+        }
+        if self.defaultness.is_some() {
+            panic!("default methods are not supported");
+        }
+        if self.sig.constness.is_some() {
+            bail_span!(
+                self.sig.constness,
+                "can only #[wasm_bindgen] non-const functions",
+            );
+        }
+
+        let opts = BindgenAttrs::find(&mut self.attrs)?;
+        let comments = extract_doc_comments(&self.attrs);
+        let (function, method_self) = function_from_decl(
+            &self.sig.ident,
+            &opts,
+            self.sig.clone(),
+            self.attrs.clone(),
+            self.vis.clone(),
+            true,
+            Some(class),
+            true,
+        )?;
+        let method_kind = if opts.constructor().is_some() {
+            ast::MethodKind::Constructor
+        } else {
+            let is_static = method_self.is_none();
+            let kind = operation_kind(&opts);
+            ast::MethodKind::Operation(ast::Operation { is_static, kind })
+        };
+        program.exports.push(ast::Export {
+            comments,
+            function,
+            js_class: Some(js_class.to_string()),
+            method_kind,
+            method_self,
+            rust_class: Some(class.clone()),
+            rust_name: self.sig.ident.clone(),
+            start: false,
+        });
+        opts.check_used();
+        Ok(())
+    }
+}
+
+fn import_enum(enum_: syn::ItemEnum, program: &mut ast::Program) -> Result<(), Diagnostic> {
+    let mut variants = vec![];
+    let mut variant_values = vec![];
+
+    for v in enum_.variants.iter() {
+        match v.fields {
+            syn::Fields::Unit => (),
+            _ => bail_span!(v.fields, "only C-Style enums allowed with #[wasm_bindgen]"),
+        }
+
+        let (_, expr) = match &v.discriminant {
+            Some(pair) => pair,
+            None => {
+                bail_span!(v, "all variants must have a value");
+            }
+        };
+        match get_expr(expr) {
+            syn::Expr::Lit(syn::ExprLit {
+                attrs: _,
+                lit: syn::Lit::Str(str_lit),
+            }) => {
+                variants.push(v.ident.clone());
+                variant_values.push(str_lit.value());
+            }
+            expr => bail_span!(
+                expr,
+                "enums with #[wasm_bindgen] cannot mix string and non-string values",
+            ),
+        }
+    }
+
+    program.imports.push(ast::Import {
+        module: None,
+        js_namespace: None,
+        kind: ast::ImportKind::Enum(ast::ImportEnum {
+            vis: enum_.vis,
+            name: enum_.ident,
+            variants,
+            variant_values,
+            rust_attrs: enum_.attrs,
+        }),
+    });
+
+    Ok(())
+}
+
+impl<'a> MacroParse<(&'a mut TokenStream, BindgenAttrs)> for syn::ItemEnum {
+    fn macro_parse(
+        self,
+        program: &mut ast::Program,
+        (tokens, opts): (&'a mut TokenStream, BindgenAttrs),
+    ) -> Result<(), Diagnostic> {
+        if self.variants.len() == 0 {
+            bail_span!(self, "cannot export empty enums to JS");
+        }
+        let generate_typescript = opts.skip_typescript().is_none();
+
+        // Check if the first value is a string literal
+        if let Some((_, expr)) = &self.variants[0].discriminant {
+            match get_expr(expr) {
+                syn::Expr::Lit(syn::ExprLit {
+                    attrs: _,
+                    lit: syn::Lit::Str(_),
+                }) => {
+                    opts.check_used();
+                    return import_enum(self, program);
+                }
+                _ => {}
+            }
+        }
+        let js_name = opts
+            .js_name()
+            .map(|s| s.0)
+            .map_or_else(|| self.ident.to_string(), |s| s.to_string());
+        opts.check_used();
+
+        let has_discriminant = self.variants[0].discriminant.is_some();
+
+        match self.vis {
+            syn::Visibility::Public(_) => {}
+            _ => bail_span!(self, "only public enums are allowed with #[wasm_bindgen]"),
+        }
+
+        let variants = self
+            .variants
+            .iter()
+            .enumerate()
+            .map(|(i, v)| {
+                match v.fields {
+                    syn::Fields::Unit => (),
+                    _ => bail_span!(v.fields, "only C-Style enums allowed with #[wasm_bindgen]"),
+                }
+
+                // Require that everything either has a discriminant or doesn't.
+                // We don't really want to get in the business of emulating how
+                // rustc assigns values to enums.
+                if v.discriminant.is_some() != has_discriminant {
+                    bail_span!(
+                        v,
+                        "must either annotate discriminant of all variants or none"
+                    );
+                }
+
+                let value = match &v.discriminant {
+                    Some((_, expr)) => match get_expr(expr) {
+                        syn::Expr::Lit(syn::ExprLit {
+                            attrs: _,
+                            lit: syn::Lit::Int(int_lit),
+                        }) => match int_lit.base10_digits().parse::<u32>() {
+                            Ok(v) => v,
+                            Err(_) => {
+                                bail_span!(
+                                    int_lit,
+                                    "enums with #[wasm_bindgen] can only support \
+                                 numbers that can be represented as u32"
+                                );
+                            }
+                        },
+                        expr => bail_span!(
+                            expr,
+                            "enums with #[wasm_bindgen] may only have \
+                             number literal values",
+                        ),
+                    },
+                    None => i as u32,
+                };
+
+                let comments = extract_doc_comments(&v.attrs);
+                Ok(ast::Variant {
+                    name: v.ident.clone(),
+                    value,
+                    comments,
+                })
+            })
+            .collect::<Result<Vec<_>, Diagnostic>>()?;
+
+        let mut values = variants.iter().map(|v| v.value).collect::<Vec<_>>();
+        values.sort();
+        let hole = values
+            .windows(2)
+            .filter_map(|window| {
+                if window[0] + 1 != window[1] {
+                    Some(window[0] + 1)
+                } else {
+                    None
+                }
+            })
+            .next()
+            .unwrap_or(*values.last().unwrap() + 1);
+        for value in values {
+            assert!(hole != value);
+        }
+
+        let comments = extract_doc_comments(&self.attrs);
+
+        self.to_tokens(tokens);
+
+        program.enums.push(ast::Enum {
+            rust_name: self.ident,
+            js_name,
+            variants,
+            comments,
+            hole,
+            generate_typescript,
+        });
+        Ok(())
+    }
+}
+
+impl MacroParse<BindgenAttrs> for syn::ItemConst {
+    fn macro_parse(self, program: &mut ast::Program, opts: BindgenAttrs) -> Result<(), Diagnostic> {
+        // Shortcut
+        if opts.typescript_custom_section().is_none() {
+            bail_span!(self, "#[wasm_bindgen] will not work on constants unless you are defining a #[wasm_bindgen(typescript_custom_section)].");
+        }
+
+        match get_expr(&self.expr) {
+            syn::Expr::Lit(syn::ExprLit {
+                lit: syn::Lit::Str(litstr),
+                ..
+            }) => {
+                program.typescript_custom_sections.push(litstr.value());
+            }
+            expr => {
+                bail_span!(expr, "Expected a string literal to be used with #[wasm_bindgen(typescript_custom_section)].");
+            }
+        }
+
+        opts.check_used();
+
+        Ok(())
+    }
+}
+
+impl MacroParse<BindgenAttrs> for syn::ItemForeignMod {
+    fn macro_parse(self, program: &mut ast::Program, opts: BindgenAttrs) -> Result<(), Diagnostic> {
+        let mut errors = Vec::new();
+        match self.abi.name {
+            Some(ref l) if l.value() == "C" => {}
+            None => {}
+            Some(ref other) => {
+                errors.push(err_span!(
+                    other,
+                    "only foreign mods with the `C` ABI are allowed"
+                ));
+            }
+        }
+        let module = if let Some((name, span)) = opts.module() {
+            if opts.inline_js().is_some() {
+                let msg = "cannot specify both `module` and `inline_js`";
+                errors.push(Diagnostic::span_error(span, msg));
+            }
+            if opts.raw_module().is_some() {
+                let msg = "cannot specify both `module` and `raw_module`";
+                errors.push(Diagnostic::span_error(span, msg));
+            }
+            Some(ast::ImportModule::Named(name.to_string(), span))
+        } else if let Some((name, span)) = opts.raw_module() {
+            if opts.inline_js().is_some() {
+                let msg = "cannot specify both `raw_module` and `inline_js`";
+                errors.push(Diagnostic::span_error(span, msg));
+            }
+            Some(ast::ImportModule::RawNamed(name.to_string(), span))
+        } else if let Some((js, span)) = opts.inline_js() {
+            let i = program.inline_js.len();
+            program.inline_js.push(js.to_string());
+            Some(ast::ImportModule::Inline(i, span))
+        } else {
+            None
+        };
+        for item in self.items.into_iter() {
+            if let Err(e) = item.macro_parse(program, module.clone()) {
+                errors.push(e);
+            }
+        }
+        Diagnostic::from_vec(errors)?;
+        opts.check_used();
+        Ok(())
+    }
+}
+
+impl MacroParse<Option<ast::ImportModule>> for syn::ForeignItem {
+    fn macro_parse(
+        mut self,
+        program: &mut ast::Program,
+        module: Option<ast::ImportModule>,
+    ) -> Result<(), Diagnostic> {
+        let item_opts = {
+            let attrs = match self {
+                syn::ForeignItem::Fn(ref mut f) => &mut f.attrs,
+                syn::ForeignItem::Type(ref mut t) => &mut t.attrs,
+                syn::ForeignItem::Static(ref mut s) => &mut s.attrs,
+                _ => panic!("only foreign functions/types allowed for now"),
+            };
+            BindgenAttrs::find(attrs)?
+        };
+        let js_namespace = item_opts.js_namespace().map(|(s, _)| s.to_owned());
+        let kind = match self {
+            syn::ForeignItem::Fn(f) => f.convert((item_opts, &module))?,
+            syn::ForeignItem::Type(t) => t.convert(item_opts)?,
+            syn::ForeignItem::Static(s) => s.convert((item_opts, &module))?,
+            _ => panic!("only foreign functions/types allowed for now"),
+        };
+
+        program.imports.push(ast::Import {
+            module,
+            js_namespace,
+            kind,
+        });
+
+        Ok(())
+    }
+}
+
+/// Get the first type parameter of a generic type, errors on incorrect input.
+fn extract_first_ty_param(ty: Option<&syn::Type>) -> Result<Option<syn::Type>, Diagnostic> {
+    let t = match ty {
+        Some(t) => t,
+        None => return Ok(None),
+    };
+    let path = match *get_ty(&t) {
+        syn::Type::Path(syn::TypePath {
+            qself: None,
+            ref path,
+        }) => path,
+        _ => bail_span!(t, "must be Result<...>"),
+    };
+    let seg = path
+        .segments
+        .last()
+        .ok_or_else(|| err_span!(t, "must have at least one segment"))?;
+    let generics = match seg.arguments {
+        syn::PathArguments::AngleBracketed(ref t) => t,
+        _ => bail_span!(t, "must be Result<...>"),
+    };
+    let generic = generics
+        .args
+        .first()
+        .ok_or_else(|| err_span!(t, "must have at least one generic parameter"))?;
+    let ty = match generic {
+        syn::GenericArgument::Type(t) => t,
+        other => bail_span!(other, "must be a type parameter"),
+    };
+    match get_ty(&ty) {
+        syn::Type::Tuple(t) if t.elems.len() == 0 => return Ok(None),
+        _ => {}
+    }
+    Ok(Some(ty.clone()))
+}
+
+/// Extract the documentation comments from a Vec of attributes
+fn extract_doc_comments(attrs: &[syn::Attribute]) -> Vec<String> {
+    attrs
+        .iter()
+        .filter_map(|a| {
+            // if the path segments include an ident of "doc" we know this
+            // this is a doc comment
+            if a.path.segments.iter().any(|s| s.ident.to_string() == "doc") {
+                Some(
+                    // We want to filter out any Puncts so just grab the Literals
+                    a.tokens.clone().into_iter().filter_map(|t| match t {
+                        TokenTree::Literal(lit) => {
+                            let quoted = lit.to_string();
+                            Some(try_unescape(&quoted).unwrap_or_else(|| quoted))
+                        }
+                        _ => None,
+                    }),
+                )
+            } else {
+                None
+            }
+        })
+        //Fold up the [[String]] iter we created into Vec<String>
+        .fold(vec![], |mut acc, a| {
+            acc.extend(a);
+            acc
+        })
+}
+
+// Unescapes a quoted string. char::escape_debug() was used to escape the text.
+fn try_unescape(s: &str) -> Option<String> {
+    if s.is_empty() {
+        return Some(String::new());
+    }
+    let mut result = String::with_capacity(s.len());
+    let mut chars = s.chars();
+    for i in 0.. {
+        let c = match chars.next() {
+            Some(c) => c,
+            None => {
+                if result.ends_with('"') {
+                    result.pop();
+                }
+                return Some(result);
+            }
+        };
+        if i == 0 && c == '"' {
+            // ignore it
+        } else if c == '\\' {
+            let c = chars.next()?;
+            match c {
+                't' => result.push('\t'),
+                'r' => result.push('\r'),
+                'n' => result.push('\n'),
+                '\\' | '\'' | '"' => result.push(c),
+                'u' => {
+                    if chars.next() != Some('{') {
+                        return None;
+                    }
+                    let (c, next) = unescape_unicode(&mut chars)?;
+                    result.push(c);
+                    if next != '}' {
+                        return None;
+                    }
+                }
+                _ => return None,
+            }
+        } else {
+            result.push(c);
+        }
+    }
+    None
+}
+
+fn unescape_unicode(chars: &mut Chars) -> Option<(char, char)> {
+    let mut value = 0;
+    for i in 0..7 {
+        let c = chars.next()?;
+        let num = if c >= '0' && c <= '9' {
+            c as u32 - '0' as u32
+        } else if c >= 'a' && c <= 'f' {
+            c as u32 - 'a' as u32 + 10
+        } else if c >= 'A' && c <= 'F' {
+            c as u32 - 'A' as u32 + 10
+        } else {
+            if i == 0 {
+                return None;
+            }
+            let decoded = char::from_u32(value)?;
+            return Some((decoded, c));
+        };
+        if i >= 6 {
+            return None;
+        }
+        value = (value << 4) | num;
+    }
+    None
+}
+
+/// Check there are no lifetimes on the function.
+fn assert_no_lifetimes(sig: &syn::Signature) -> Result<(), Diagnostic> {
+    struct Walk {
+        diagnostics: Vec<Diagnostic>,
+    }
+
+    impl<'ast> syn::visit::Visit<'ast> for Walk {
+        fn visit_lifetime(&mut self, i: &'ast syn::Lifetime) {
+            self.diagnostics.push(err_span!(
+                &*i,
+                "it is currently not sound to use lifetimes in function \
+                 signatures"
+            ));
+        }
+    }
+    let mut walk = Walk {
+        diagnostics: Vec::new(),
+    };
+    syn::visit::Visit::visit_signature(&mut walk, sig);
+    Diagnostic::from_vec(walk.diagnostics)
+}
+
+/// Extracts the last ident from the path
+fn extract_path_ident(path: &syn::Path) -> Result<Ident, Diagnostic> {
+    for segment in path.segments.iter() {
+        match segment.arguments {
+            syn::PathArguments::None => {}
+            _ => bail_span!(path, "paths with type parameters are not supported yet"),
+        }
+    }
+
+    match path.segments.last() {
+        Some(value) => Ok(value.ident.clone()),
+        None => {
+            bail_span!(path, "empty idents are not supported");
+        }
+    }
+}
+
+pub fn reset_attrs_used() {
+    ATTRS.with(|state| {
+        state.parsed.set(0);
+        state.checks.set(0);
+        state.unused_attrs.borrow_mut().clear();
+    })
+}
+
+pub fn check_unused_attrs(tokens: &mut TokenStream) {
+    ATTRS.with(|state| {
+        assert_eq!(state.parsed.get(), state.checks.get());
+        let unused_attrs = &*state.unused_attrs.borrow();
+        if !unused_attrs.is_empty() {
+            tokens.extend(quote::quote! {
+                // Anonymous scope to prevent name clashes.
+                const _: () = {
+                    #(let #unused_attrs: ();)*
+                };
+            });
+        }
+    })
+}
+
+fn operation_kind(opts: &BindgenAttrs) -> ast::OperationKind {
+    let mut operation_kind = ast::OperationKind::Regular;
+    if let Some(g) = opts.getter() {
+        operation_kind = ast::OperationKind::Getter(g.clone());
+    }
+    if let Some(s) = opts.setter() {
+        operation_kind = ast::OperationKind::Setter(s.clone());
+    }
+    if opts.indexing_getter().is_some() {
+        operation_kind = ast::OperationKind::IndexingGetter;
+    }
+    if opts.indexing_setter().is_some() {
+        operation_kind = ast::OperationKind::IndexingSetter;
+    }
+    if opts.indexing_deleter().is_some() {
+        operation_kind = ast::OperationKind::IndexingDeleter;
+    }
+    operation_kind
+}