Switch from failure to anyhow (#1851)

This commit switches all of `wasm-bindgen` from the `failure` crate to
`anyhow`. The `anyhow` crate should serve all the purposes that we
previously used `failure` for but has a few advantages:

* It's based on the standard `Error` trait rather than a custom `Fail`
  trait, improving ecosystem compatibility.
* We don't need a `#[derive(Fail)]`, which means that's less code to
  compile for `wasm-bindgen`. This notably helps the compile time of
  `web-sys` itself.
* Using `Result<()>` in `fn main` with `anyhow::Error` produces
  human-readable output, so we can use that natively.

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

@@ -8,7 +8,7 @@ use crate::js::incoming;
 use crate::js::outgoing;
 use crate::js::Context;
 use crate::webidl::Binding;
-use failure::{bail, Error};
+use anyhow::{bail, Error};
 use std::collections::HashSet;
 use wasm_webidl_bindings::ast;
 

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

@@ -8,7 +8,7 @@ use crate::descriptor::VectorKind;
 use crate::js::binding::JsBuilder;
 use crate::js::Context;
 use crate::webidl::NonstandardIncoming;
-use failure::{bail, Error};
+use anyhow::{bail, Error};
 use wasm_webidl_bindings::ast;
 
 pub struct Incoming<'a, 'b> {

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

@@ -5,7 +5,7 @@ use crate::webidl::{AuxEnum, AuxExport, AuxExportKind, AuxImport, AuxStruct};
 use crate::webidl::{AuxValue, Binding};
 use crate::webidl::{JsImport, JsImportName, NonstandardWebidlSection, WasmBindgenAux};
 use crate::{Bindgen, EncodeInto, OutputMode};
-use failure::{bail, Error, ResultExt};
+use anyhow::{bail, Context as _, Error};
 use std::collections::{BTreeMap, BTreeSet, HashMap, HashSet};
 use std::fs;
 use std::path::{Path, PathBuf};
@@ -1888,7 +1888,7 @@ impl<'a> Context<'a> {
         check_duplicated_getter_and_setter_names(&pairs)?;
         for (id, export) in pairs {
             self.generate_export(*id, export, bindings)
-                .with_context(|_| {
+                .with_context(|| {
                     format!(
                         "failed to generate bindings for Rust export `{}`",
                         export.debug_name,
@@ -1901,7 +1901,7 @@ impl<'a> Context<'a> {
             let catch = aux.imports_with_catch.contains(&id);
             let assert_no_shim = aux.imports_with_assert_no_shim.contains(&id);
             self.generate_import(*id, import, bindings, variadic, catch, assert_no_shim)
-                .with_context(|_| {
+                .with_context(|| {
                     format!("failed to generate bindings for import `{:?}`", import,)
                 })?;
         }

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

@@ -6,7 +6,7 @@ use crate::descriptor::VectorKind;
 use crate::js::binding::JsBuilder;
 use crate::js::Context;
 use crate::webidl::NonstandardOutgoing;
-use failure::{bail, Error};
+use anyhow::{bail, Error};
 use wasm_webidl_bindings::ast;
 
 pub struct Outgoing<'a, 'b> {