rustdoc: Encode ABI in all methods

This commit ensures that the ABI of functions is propagated all the way through
to the documentation.

Closes #22038

src/test/auxiliary/issue-22025.rs

@@ -0,0 +1,18 @@
+// Copyright 2015 The Rust Project Developers. See the COPYRIGHT
+// file at the top-level directory of this distribution and at
+// http://rust-lang.org/COPYRIGHT.
+//
+// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
+// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
+// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
+// option. This file may not be copied, modified, or distributed
+// except according to those terms.
+
+pub mod foo {
+
+    pub trait Foo {}
+    pub struct Bar;
+
+    impl Foo for Bar {}
+
+}

src/test/rustdoc/ffi.rs

@@ -12,10 +12,10 @@
 
 extern crate rustdoc_ffi as lib;
 
-// @has ffi/fn.foreigner.html //pre 'pub unsafe fn foreigner(cold_as_ice: u32)'
+// @has ffi/fn.foreigner.html //pre 'pub unsafe extern fn foreigner(cold_as_ice: u32)'
 pub use lib::foreigner;
 
 extern "C" {
-    // @has ffi/fn.another.html //pre 'pub unsafe fn another(cold_as_ice: u32)'
+    // @has ffi/fn.another.html //pre 'pub unsafe extern fn another(cold_as_ice: u32)'
     pub fn another(cold_as_ice: u32);
 }

src/test/rustdoc/issue-22025.rs

@@ -0,0 +1,15 @@
+// Copyright 2015 The Rust Project Developers. See the COPYRIGHT
+// file at the top-level directory of this distribution and at
+// http://rust-lang.org/COPYRIGHT.
+//
+// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
+// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
+// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
+// option. This file may not be copied, modified, or distributed
+// except according to those terms.
+
+// aux-build:issue-22025.rs
+
+extern crate issue_22025;
+
+pub use issue_22025::foo::{Foo, Bar};

src/test/rustdoc/issue-22038.rs

@@ -0,0 +1,29 @@
+// Copyright 2015 The Rust Project Developers. See the COPYRIGHT
+// file at the top-level directory of this distribution and at
+// http://rust-lang.org/COPYRIGHT.
+//
+// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
+// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
+// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
+// option. This file may not be copied, modified, or distributed
+// except according to those terms.
+
+extern {
+    // @has issue_22038/fn.foo1.html \
+    //      '//*[@class="rust fn"]' 'pub unsafe extern fn foo1()'
+    pub fn foo1();
+}
+
+extern "system" {
+    // @has issue_22038/fn.foo2.html \
+    //      '//*[@class="rust fn"]' 'pub unsafe extern "system" fn foo2()'
+    pub fn foo2();
+}
+
+// @has issue_22038/fn.bar.html \
+//      '//*[@class="rust fn"]' 'pub extern fn bar()'
+pub extern fn bar() {}
+
+// @has issue_22038/fn.baz.html \
+//      '//*[@class="rust fn"]' 'pub extern "system" fn baz()'
+pub extern "system" fn baz() {}