Update tests for extern block linting

compiler/rustc_error_codes/src/error_codes/E0044.md

@@ -3,13 +3,13 @@ You cannot use type or const parameters on foreign items.
 Example of erroneous code:
 
 ```compile_fail,E0044
-extern { fn some_func<T>(x: T); }
+extern "C" { fn some_func<T>(x: T); }
 ```
 
 To fix this, replace the generic parameter with the specializations that you
 need:
 
 ```
-extern { fn some_func_i32(x: i32); }
-extern { fn some_func_i64(x: i64); }
+extern "C" { fn some_func_i32(x: i32); }
+extern "C" { fn some_func_i64(x: i64); }
 ```

compiler/rustc_error_codes/src/error_codes/E0130.md

@@ -3,7 +3,7 @@ A pattern was declared as an argument in a foreign function declaration.
 Erroneous code example:
 
 ```compile_fail,E0130
-extern {
+extern "C" {
     fn foo((a, b): (u32, u32)); // error: patterns aren't allowed in foreign
                                 //        function declarations
 }
@@ -17,7 +17,7 @@ struct SomeStruct {
     b: u32,
 }
 
-extern {
+extern "C" {
     fn foo(s: SomeStruct); // ok!
 }
 ```
@@ -25,7 +25,7 @@ extern {
 Or:
 
 ```
-extern {
+extern "C" {
     fn foo(a: (u32, u32)); // ok!
 }
 ```

compiler/rustc_error_codes/src/error_codes/E0454.md

@@ -3,7 +3,7 @@ A link name was given with an empty name.
 Erroneous code example:
 
 ```compile_fail,E0454
-#[link(name = "")] extern {}
+#[link(name = "")] extern "C" {}
 // error: `#[link(name = "")]` given with empty name
 ```
 
@@ -11,5 +11,5 @@ The rust compiler cannot link to an external library if you don't give it its
 name. Example:
 
 ```no_run
-#[link(name = "some_lib")] extern {} // ok!
+#[link(name = "some_lib")] extern "C" {} // ok!
 ```

compiler/rustc_error_codes/src/error_codes/E0455.md

@@ -4,7 +4,7 @@ as frameworks are specific to that operating system.
 Erroneous code example:
 
 ```ignore (should-compile_fail-but-cannot-doctest-conditionally-without-macos)
-#[link(name = "FooCoreServices", kind = "framework")] extern {}
+#[link(name = "FooCoreServices", kind = "framework")] extern "C" {}
 // OS used to compile is Linux for example
 ```
 
@@ -12,7 +12,7 @@ To solve this error you can use conditional compilation:
 
 ```
 #[cfg_attr(target="macos", link(name = "FooCoreServices", kind = "framework"))]
-extern {}
+extern "C" {}
 ```
 
 Learn more in the [Conditional Compilation][conditional-compilation] section

compiler/rustc_error_codes/src/error_codes/E0458.md

@@ -3,7 +3,7 @@ An unknown "kind" was specified for a link attribute.
 Erroneous code example:
 
 ```compile_fail,E0458
-#[link(kind = "wonderful_unicorn")] extern {}
+#[link(kind = "wonderful_unicorn")] extern "C" {}
 // error: unknown kind: `wonderful_unicorn`
 ```
 

compiler/rustc_error_codes/src/error_codes/E0459.md

@@ -3,7 +3,7 @@ A link was used without a name parameter.
 Erroneous code example:
 
 ```compile_fail,E0459
-#[link(kind = "dylib")] extern {}
+#[link(kind = "dylib")] extern "C" {}
 // error: `#[link(...)]` specified without `name = "foo"`
 ```
 
@@ -11,5 +11,5 @@ Please add the name parameter to allow the rust compiler to find the library
 you want. Example:
 
 ```no_run
-#[link(kind = "dylib", name = "some_lib")] extern {} // ok!
+#[link(kind = "dylib", name = "some_lib")] extern "C" {} // ok!
 ```

compiler/rustc_error_codes/src/error_codes/E0617.md

@@ -3,7 +3,7 @@ Attempted to pass an invalid type of variable into a variadic function.
 Erroneous code example:
 
 ```compile_fail,E0617
-extern {
+extern "C" {
     fn printf(c: *const i8, ...);
 }
 
@@ -21,7 +21,7 @@ to import from `std::os::raw`).
 In this case, `c_double` has the same size as `f64` so we can use it directly:
 
 ```no_run
-# extern {
+# extern "C" {
 #     fn printf(c: *const i8, ...);
 # }
 unsafe {

compiler/rustc_error_codes/src/error_codes/E0724.md

@@ -18,7 +18,7 @@ the function inside of an `extern` block.
 ```
 #![feature(ffi_returns_twice)]
 
-extern {
+extern "C" {
    #[ffi_returns_twice] // ok!
    pub fn foo();
 }