Improve the performance of 'string enums'

[Davidster]

Closes #3468

[Davidster]

For your convenience, this is what a fully-expanded ImportEnum looks like now:

#![feature(prelude_import)]
//! Raw API bindings for Web APIs
//!
//! This is a procedurally generated crate from browser WebIDL which provides a
//! binding to all APIs that browsers provide on the web.
//!
//! This crate by default contains very little when compiled as almost all of
//! its exposed APIs are gated by Cargo features. The exhaustive list of
//! features can be found in `crates/web-sys/Cargo.toml`, but the rule of thumb
//! for `web-sys` is that each type has its own cargo feature (named after the
//! type). Using an API requires enabling the features for all types used in the
//! API, and APIs should mention in the documentation what features they
//! require.
#![doc(html_root_url = "https://docs.rs/web-sys/0.3")]
#![allow(deprecated)]
#[prelude_import]
use std::prelude::rust_2018::*;
#[macro_use]
extern crate std;
mod features {
    #[cfg(feature = "RequestMode")]
    #[allow(non_snake_case)]
    mod gen_RequestMode {
        #![allow(unused_imports)]
        #![allow(clippy::all)]
        use wasm_bindgen::prelude::*;
        ///The `RequestMode` enum.
        ///
        ///*This API requires the following crate features to be activated: `RequestMode`*
        #[non_exhaustive]
        #[repr(u32)]
        pub enum RequestMode {
            SameOrigin = 0u32,
            NoCors = 1u32,
            Cors = 2u32,
            Navigate = 3u32,
            #[automatically_derived]
            #[doc(hidden)]
            __Invalid,
        }
        #[automatically_derived]
        impl ::core::fmt::Debug for RequestMode {
            #[inline]
            fn fmt(&self, f: &mut ::core::fmt::Formatter) -> ::core::fmt::Result {
                ::core::fmt::Formatter::write_str(
                    f,
                    match self {
                        RequestMode::SameOrigin => "SameOrigin",
                        RequestMode::NoCors => "NoCors",
                        RequestMode::Cors => "Cors",
                        RequestMode::Navigate => "Navigate",
                        RequestMode::__Invalid => "__Invalid",
                    },
                )
            }
        }
        #[automatically_derived]
        impl ::core::clone::Clone for RequestMode {
            #[inline]
            fn clone(&self) -> RequestMode {
                *self
            }
        }
        #[automatically_derived]
        impl ::core::marker::Copy for RequestMode {}
        #[automatically_derived]
        impl ::core::marker::StructuralPartialEq for RequestMode {}
        #[automatically_derived]
        impl ::core::cmp::PartialEq for RequestMode {
            #[inline]
            fn eq(&self, other: &RequestMode) -> bool {
                let __self_tag = ::core::intrinsics::discriminant_value(self);
                let __arg1_tag = ::core::intrinsics::discriminant_value(other);
                __self_tag == __arg1_tag
            }
        }
        #[automatically_derived]
        impl ::core::marker::StructuralEq for RequestMode {}
        #[automatically_derived]
        impl ::core::cmp::Eq for RequestMode {
            #[inline]
            #[doc(hidden)]
            #[coverage(off)]
            fn assert_receiver_is_total_eq(&self) -> () {}
        }
        #[automatically_derived]
        impl wasm_bindgen::convert::IntoWasmAbi for RequestMode {
            type Abi = u32;
            #[inline]
            fn into_abi(self) -> u32 {
                self as u32
            }
        }
        #[automatically_derived]
        impl wasm_bindgen::convert::FromWasmAbi for RequestMode {
            type Abi = u32;
            unsafe fn from_abi(val: u32) -> Self {
                match val {
                    0u32 => RequestMode::SameOrigin,
                    1u32 => RequestMode::NoCors,
                    2u32 => RequestMode::Cors,
                    3u32 => RequestMode::Navigate,
                    4u32 => RequestMode::__Invalid,
                    _ => {
                        ::core::panicking::unreachable_display(
                            &"The JS binding should only ever produce a valid value or the specific 'invalid' value",
                        );
                    }
                }
            }
        }
        #[automatically_derived]
        impl wasm_bindgen::convert::OptionFromWasmAbi for RequestMode {
            #[inline]
            fn is_none(val: &u32) -> bool {
                *val == 5u32
            }
        }
        #[automatically_derived]
        impl wasm_bindgen::convert::OptionIntoWasmAbi for RequestMode {
            #[inline]
            fn none() -> Self::Abi {
                5u32
            }
        }
        #[automatically_derived]
        impl wasm_bindgen::describe::WasmDescribe for RequestMode {
            fn describe() {
                use wasm_bindgen::describe::*;
                inform(IMPORT_ENUM);
                inform(11u32);
                inform(82u32);
                inform(101u32);
                inform(113u32);
                inform(117u32);
                inform(101u32);
                inform(115u32);
                inform(116u32);
                inform(77u32);
                inform(111u32);
                inform(100u32);
                inform(101u32);
                inform(4u32);
                inform(5u32);
                inform(4u32);
                inform(11u32);
                inform(115u32);
                inform(97u32);
                inform(109u32);
                inform(101u32);
                inform(45u32);
                inform(111u32);
                inform(114u32);
                inform(105u32);
                inform(103u32);
                inform(105u32);
                inform(110u32);
                inform(7u32);
                inform(110u32);
                inform(111u32);
                inform(45u32);
                inform(99u32);
                inform(111u32);
                inform(114u32);
                inform(115u32);
                inform(4u32);
                inform(99u32);
                inform(111u32);
                inform(114u32);
                inform(115u32);
                inform(8u32);
                inform(110u32);
                inform(97u32);
                inform(118u32);
                inform(105u32);
                inform(103u32);
                inform(97u32);
                inform(116u32);
                inform(101u32);
            }
        }
        #[automatically_derived]
        impl wasm_bindgen::__rt::core::convert::From<RequestMode>
        for wasm_bindgen::JsValue {
            fn from(val: RequestMode) -> Self {
                wasm_bindgen::JsValue::from_str(
                    match val {
                        RequestMode::SameOrigin => "same-origin",
                        RequestMode::NoCors => "no-cors",
                        RequestMode::Cors => "cors",
                        RequestMode::Navigate => "navigate",
                        RequestMode::__Invalid => {
                            wasm_bindgen::throw_str(
                                "Converting an invalid import enum back to a string is currently not supported",
                            )
                        }
                        _ => {
                            ::core::panicking::unreachable_display(
                                &"All possible variants should have been checked",
                            );
                        }
                    },
                )
            }
        }
    }
    #[cfg(feature = "RequestMode")]
    #[allow(unused_imports)]
    pub use gen_RequestMode::*;
}
pub use features::*;
pub use js_sys;
pub use wasm_bindgen;

[Davidster]

I'm not sure what's going on with the CI. The cargo test --manifest-path crates/web-sys/Cargo.toml --target wasm32-unknown-unknown --all-features test passes locally for me. Any ideas?

[daxpedda]

Apologies for the delay, I was on vacation, still catching up.
Planning to take a look tomorrow!

I'm not sure what's going on with the CI. The cargo test --manifest-path crates/web-sys/Cargo.toml --target wasm32-unknown-unknown --all-features test passes locally for me. Any ideas?

Run with RUSTFLAGS=--cfg=web_sys_unstable_apis, which reproduced the bug for me locally as well.

[Davidster]

No worries! Thanks I missed the flag

[MartensCedric]

LGTM

[adrientremblay]

Good job

[daxpedda]

Looks great so far, basically just a couple of nits.

Again, I apologize for the delay, I extended my vacation a bit spontaneously.

[daxpedda]

LGTM!

@Liamolucko would appreciate your review/approval as well!

[Davidster]

thanks for the review!

[Liamolucko]

Looks great!

[daxpedda]

@Davidster thank you for your contribution!