Consistently use extern "C"

This is what rustfmt favors, so let's favor it too!

Closes #1042

guide/src/reference/attributes/on-js-imports/catch.md

@@ -6,7 +6,7 @@ attached to any imported function or method, and the function must return a
 
 ```rust
 #[wasm_bindgen]
-extern {
+extern "C" {
     // `catch` on a standalone function.
     #[wasm_bindgen(catch)]
     fn foo() -> Result<(), JsValue>;

guide/src/reference/attributes/on-js-imports/constructor.md

@@ -7,7 +7,7 @@ used in the generated glue:
 
 ```rust
 #[wasm_bindgen]
-extern {
+extern "C" {
     type Shoes;
 
     #[wasm_bindgen(constructor)]

guide/src/reference/attributes/on-js-imports/extends.md

@@ -7,7 +7,7 @@ the inheritance hierarchy:
 
 ```rust
 #[wasm_bindgen]
-extern {
+extern "C" {
     type Foo;
 
     #[wasm_bindgen(extends = Foo)]
@@ -33,7 +33,7 @@ the types.
 
 ```rust
 #[wasm_bindgen]
-extern {
+extern "C" {
     type Foo;
 
     #[wasm_bindgen(extends = Foo)]

guide/src/reference/attributes/on-js-imports/final.md

@@ -21,7 +21,7 @@ today:
 
 ```rust
 #[wasm_bindgen]
-extern {
+extern "C" {
     type Foo;
     #[wasm_bindgen(method)]
     fn bar(this: &Foo, argument: &str) -> JsValue;
@@ -47,7 +47,7 @@ If we instead, however, write this:
 
 ```rust
 #[wasm_bindgen]
-extern {
+extern "C" {
     type Foo;
     #[wasm_bindgen(method, final)] // note the change here
     fn bar(this: &Foo, argument: &str) -> JsValue;

guide/src/reference/attributes/on-js-imports/getter-and-setter.md

@@ -24,7 +24,7 @@ We would import this with the following `#[wasm_bindgen]` attributes:
 
 ```rust
 #[wasm_bindgen]
-extern {
+extern "C" {
     type TheDude;
 
     #[wasm_bindgen(method, getter)]
@@ -48,7 +48,7 @@ example the below is equivalent to the above:
 
 ```rust
 #[wasm_bindgen]
-extern {
+extern "C" {
     type TheDude;
 
     #[wasm_bindgen(method, getter = white_russians)]

guide/src/reference/attributes/on-js-imports/index.md

@@ -1,5 +1,5 @@
 # `#[wasm_bindgen]` on JavaScript Imports
 
 This section enumerates the attributes available for customizing bindings for
-JavaScript functions and classes imported into Rust within an `extern { ... }`
+JavaScript functions and classes imported into Rust within an `extern "C" { ... }`
 block.

guide/src/reference/attributes/on-js-imports/indexing-getter-setter-deleter.md

@@ -58,7 +58,7 @@ on methods:
 
 ```rust
 #[wasm_bindgen]
-extern {
+extern "C" {
     type Foo;
     static foo: Foo;
 

guide/src/reference/attributes/on-js-imports/js_class.md

@@ -6,7 +6,7 @@ Rust side.
 
 ```rust
 #[wasm_bindgen]
-extern {
+extern "C" {
     // We don't want to import JS strings as `String`, since Rust already has a
     // `String` type in its prelude, so rename it as `JsString`.
     #[wasm_bindgen(js_name = String)]

guide/src/reference/attributes/on-js-imports/js_name.md

@@ -8,7 +8,7 @@ snake-cased Rust identifier:
 
 ```rust
 #[wasm_bindgen]
-extern {
+extern "C" {
     #[wasm_bindgen(js_name = jsOftenUsesCamelCase)]
     fn js_often_uses_camel_case() -> u32;
 }
@@ -20,7 +20,7 @@ identifiers, in which case `js_name = "some string"` is used instead of `js_name
 
 ```rust
 #[wasm_bindgen]
-extern {
+extern "C" {
     #[wasm_bindgen(js_name = "$$$")]
     fn cash_money() -> u32;
 }
@@ -30,7 +30,7 @@ polymorphic JavaScript functions:
 
 ```rust
 #[wasm_bindgen]
-extern {
+extern "C" {
     #[wasm_bindgen(js_namespace = console, js_name = log)]
     fn console_log_str(s: &str);
 
@@ -50,7 +50,7 @@ Note that if you use `js_name` when importing a type you'll also need to use the
 
 ```rust
 #[wasm_bindgen]
-extern {
+extern "C" {
     #[wasm_bindgen(js_name = String)]
     type JsString;
     #[wasm_bindgen(method, getter, js_class = "String")]

guide/src/reference/attributes/on-js-imports/js_namespace.md

@@ -8,7 +8,7 @@ name (like a class or function name) it'll be accessed through this namespace.
 
 ```rust
 #[wasm_bindgen]
-extern {
+extern "C" {
     #[wasm_bindgen(js_namespace = console)]
     fn log(s: &str);
 }

guide/src/reference/attributes/on-js-imports/method.md

@@ -6,7 +6,7 @@ which is a shared reference to an imported JavaScript type.
 
 ```rust
 #[wasm_bindgen]
-extern {
+extern "C" {
     type Set;
 
     #[wasm_bindgen(method)]

guide/src/reference/attributes/on-js-imports/module.md

@@ -5,7 +5,7 @@ example,
 
 ```rust
 #[wasm_bindgen(module = "wu/tang/clan")]
-extern {
+extern "C" {
     type ThirtySixChambers;
 }
 ```
@@ -21,7 +21,7 @@ instead. For example,
 
 ```rust
 #[wasm_bindgen]
-extern {
+extern "C" {
     fn illmatic() -> u32;
 }
 ```

guide/src/reference/attributes/on-js-imports/static_method_of.md

@@ -6,7 +6,7 @@ to JavaScript's `Date.now()` static method, one would use this attribute:
 
 ```rust
 #[wasm_bindgen]
-extern {
+extern "C" {
     type Date;
 
     #[wasm_bindgen(static_method_of = Date)]

guide/src/reference/attributes/on-js-imports/structural.md

@@ -18,7 +18,7 @@ dynamically walked on every access.
 
 ```rust
 #[wasm_bindgen]
-extern {
+extern "C" {
     type Duck;
 
     #[wasm_bindgen(method, structural)]

guide/src/reference/attributes/on-js-imports/variadic.md

@@ -28,7 +28,7 @@ function as variadic:
 
 ```rust
 #[wasm_bindgen]
-extern {
+extern "C" {
     #[wasm_bindgen(variadic)]
     fn sum(args: &[i32]) -> i32;
 }

guide/src/reference/attributes/on-js-imports/vendor_prefix.md

@@ -9,7 +9,7 @@ For example to use `AudioContext` you might do:
 
 ```rust
 #[wasm_bindgen]
-extern {
+extern "C" {
     #[wasm_bindgen(vendor_prefix = webkit)]
     type AudioContext;
 

guide/src/reference/no-esm.md

@@ -13,7 +13,7 @@ also [follow along in the repository][repo].
 
 ```rust
 #[wasm_bindgen]
-extern {
+extern "C" {
     fn alert(msg: &str);
 }
 

guide/src/reference/passing-rust-closures-to-js.md

@@ -18,7 +18,7 @@ FnMut` trait objects:
 // Import JS functions that take closures
 
 #[wasm_bindgen]
-extern {
+extern "C" {
     fn takes_immutable_closure(f: &Fn());
 
     fn takes_mutable_closure(f: &mut FnMut());
@@ -44,7 +44,7 @@ Closures also support arguments and return values like exports do, for example:
 
 ```rust
 #[wasm_bindgen]
-extern {
+extern "C" {
     fn takes_closure_that_takes_int_and_returns_string(x: &Fn(u32) -> String);
 }
 
@@ -80,7 +80,7 @@ as arguments and returns.
 
 ```rust
 #[wasm_bindgen]
-extern {
+extern "C" {
     fn setInterval(closure: &Closure<FnMut()>, millis: u32) -> f64;
     fn cancelInterval(token: f64);
 

guide/src/reference/rust-targets.md

@@ -32,7 +32,7 @@ will unconditionally panic on non-wasm targets. For example:
 
 ```rust
 #[wasm_bindgen]
-extern {
+extern "C" {
     #[wasm_bindgen(js_namespace = console)]
     fn log(s: &str);
 }