Auto merge of #27330 - alexcrichton:reenable-lto-syntax-extension, r=huonw

The functionality this was testing was removed somewhere along the line, and
this commit restores what it was testing.

Closes #20586

Author: bors

src/test/run-make/lto-syntax-extension/lib.rs renamed to src/test/auxiliary/lto-syntax-extension-lib.rs

@@ -1,4 +1,4 @@
-// Copyright 2014 The Rust Project Developers. See the COPYRIGHT
+// 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.
 //
@@ -8,4 +8,8 @@
 // option. This file may not be copied, modified, or distributed
 // except according to those terms.
 
+// no-prefer-dynamic
+
 #![crate_type = "rlib"]
+
+pub fn foo() {}

src/test/run-make/lto-syntax-extension/main.rs renamed to src/test/auxiliary/lto-syntax-extension-plugin.rs

@@ -1,4 +1,4 @@
-// Copyright 2014 The Rust Project Developers. See the COPYRIGHT
+// 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.
 //
@@ -8,9 +8,14 @@
 // option. This file may not be copied, modified, or distributed
 // except according to those terms.
 
+// force-host
+
+#![feature(plugin_registrar)]
 #![feature(rustc_private)]
 
-extern crate lib;
-#[macro_use] extern crate log;
+extern crate rustc;
+
+use rustc::plugin::Registry;
 
-fn main() {}
+#[plugin_registrar]
+pub fn plugin_registrar(_reg: &mut Registry) {}

src/test/run-make/lto-syntax-extension/Makefile

@@ -0,0 +1,24 @@
+// 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:lto-syntax-extension-lib.rs
+// aux-build:lto-syntax-extension-plugin.rs
+// compile-flags:-C lto
+// ignore-stage1
+// no-prefer-dynamic
+
+#![feature(plugin)]
+#![plugin(lto_syntax_extension_plugin)]
+
+extern crate lto_syntax_extension_lib;
+
+fn main() {
+    lto_syntax_extension_lib::foo();
+}