Auto merge of #22026 - kmcallister:plugin, r=sfackler

```rust
#[plugin] #[no_link] extern crate bleh;
```

becomes a crate attribute

```rust
#![plugin(bleh)]
```

The feature gate is still required.

It's almost never correct to link a plugin into the resulting library / executable, because it will bring all of libsyntax and librustc with it. However if you really want this behavior, you can get it with a separate `extern crate` item in addition to the `plugin` attribute.

Fixes #21043.
Fixes #20769.

[breaking-change]

src/test/auxiliary/plugin_args.rs

@@ -27,7 +27,7 @@ use syntax::ptr::P;
 use rustc::plugin::Registry;
 
 struct Expander {
-    args: P<ast::MetaItem>,
+    args: Vec<P<ast::MetaItem>>,
 }
 
 impl TTMacroExpander for Expander {
@@ -35,10 +35,9 @@ impl TTMacroExpander for Expander {
                    ecx: &'cx mut ExtCtxt,
                    sp: Span,
                    _: &[ast::TokenTree]) -> Box<MacResult+'cx> {
-
-        let attr = ecx.attribute(sp, self.args.clone());
-        let src = pprust::attribute_to_string(&attr);
-        let interned = token::intern_and_get_ident(&src);
+        let args = self.args.iter().map(|i| pprust::meta_item_to_string(&*i))
+            .collect::<Vec<_>>().connect(", ");
+        let interned = token::intern_and_get_ident(&args[]);
         MacExpr::new(ecx.expr_str(sp, interned))
     }
 }

src/test/auxiliary/syntax_extension_with_dll_deps_2.rs

@@ -13,7 +13,7 @@
 #![crate_type = "dylib"]
 #![feature(plugin_registrar, quote)]
 
-extern crate "syntax-extension-with-dll-deps-1" as other;
+extern crate "syntax_extension_with_dll_deps_1" as other;
 extern crate syntax;
 extern crate rustc;
 

src/test/compile-fail-fulldeps/gated-plugin.rs

@@ -11,7 +11,7 @@
 // aux-build:macro_crate_test.rs
 // ignore-stage1
 
-#[plugin] #[no_link] extern crate macro_crate_test;
+#![plugin(macro_crate_test)]
 //~^ ERROR compiler plugins are experimental and possibly buggy
 
 fn main() {}

src/test/compile-fail-fulldeps/lint-group-plugin-deny-cmdline.rs

@@ -13,9 +13,7 @@
 // compile-flags: -D lint-me
 
 #![feature(plugin)]
-
-#[plugin] #[no_link]
-extern crate lint_group_plugin_test;
+#![plugin(lint_group_plugin_test)]
 
 fn lintme() { } //~ ERROR item is named 'lintme'
 

src/test/compile-fail-fulldeps/lint-plugin-deny-attr.rs

@@ -12,11 +12,9 @@
 // ignore-stage1
 
 #![feature(plugin)]
+#![plugin(lint_plugin_test)]
 #![deny(test_lint)]
 
-#[plugin] #[no_link]
-extern crate lint_plugin_test;
-
 fn lintme() { } //~ ERROR item is named 'lintme'
 
 pub fn main() {

src/test/compile-fail-fulldeps/lint-plugin-deny-cmdline.rs

@@ -13,9 +13,7 @@
 // compile-flags: -D test-lint
 
 #![feature(plugin)]
-
-#[plugin] #[no_link]
-extern crate lint_plugin_test;
+#![plugin(lint_plugin_test)]
 
 fn lintme() { } //~ ERROR item is named 'lintme'
 

src/test/compile-fail-fulldeps/lint-plugin-forbid-attrs.rs

@@ -12,11 +12,9 @@
 // ignore-stage1
 
 #![feature(plugin)]
+#![plugin(lint_plugin_test)]
 #![forbid(test_lint)]
 
-#[plugin] #[no_link]
-extern crate lint_plugin_test;
-
 fn lintme() { } //~ ERROR item is named 'lintme'
 
 #[allow(test_lint)] //~ ERROR allow(test_lint) overruled by outer forbid(test_lint)

src/test/compile-fail-fulldeps/lint-plugin-forbid-cmdline.rs

@@ -13,9 +13,7 @@
 // compile-flags: -F test-lint
 
 #![feature(plugin)]
-
-#[plugin] #[no_link]
-extern crate lint_plugin_test;
+#![plugin(lint_plugin_test)]
 
 fn lintme() { } //~ ERROR item is named 'lintme'
 

src/test/compile-fail-fulldeps/macro-crate-cannot-read-embedded-ident.rs

@@ -21,9 +21,7 @@
 // ident form.
 
 #![feature(plugin)]
-
-#[plugin] #[no_link]
-extern crate macro_crate_test;
+#![plugin(macro_crate_test)]
 
 fn main() {
     let x = 0;

src/test/compile-fail-fulldeps/macro-crate-rlib.rs

@@ -15,7 +15,7 @@
 // ignore-cross-compile gives a different error message
 
 #![feature(plugin)]
-#[plugin] #[no_link] extern crate rlib_crate_test;
+#![plugin(rlib_crate_test)]
 //~^ ERROR: plugin crate `rlib_crate_test` only found in rlib format, but must be available in dylib format
 
 fn main() {}

src/test/compile-fail-fulldeps/plugin-MacroRulesTT.rs

@@ -14,8 +14,6 @@
 // error-pattern: plugin tried to register a new MacroRulesTT
 
 #![feature(plugin)]
-
-#[plugin] #[no_link]
-extern crate macro_crate_MacroRulesTT;
+#![plugin(macro_crate_MacroRulesTT)]
 
 fn main() { }

src/test/compile-fail/malformed-plugin-1.rs

@@ -8,8 +8,6 @@
 // option. This file may not be copied, modified, or distributed
 // except according to those terms.
 
-#[plugin]
-#[plugin]  //~ ERROR #[plugin] specified multiple times
-extern crate std;
+#![plugin] //~ ERROR malformed plugin attribute
 
 fn main() {}

src/test/compile-fail/malformed-plugin-2.rs

@@ -8,15 +8,6 @@
 // option. This file may not be copied, modified, or distributed
 // except according to those terms.
 
-// aux-build:plugin_args.rs
-// ignore-stage1
+#![plugin="bleh"] //~ ERROR malformed plugin attribute
 
-#![feature(plugin)]
-
-#[no_link]
-#[plugin="foobar"]
-extern crate plugin_args;
-
-fn main() {
-    assert_eq!(plugin_args!(), "#[plugin = \"foobar\"]");
-}
+fn main() {}

src/test/compile-fail/malformed-plugin-3.rs

@@ -0,0 +1,13 @@
+// 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.
+
+#![plugin(foo="bleh")] //~ ERROR malformed plugin attribute
+
+fn main() {}

src/test/compile-fail/plugin-extern-crate-attr-deprecated.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.
+
+#[plugin]  //~ ERROR #[plugin] on `extern crate` is deprecated
+//~^ HELP use a crate attribute instead, i.e. #![plugin(std)]
+extern crate std;
+
+fn main() {}

src/test/run-pass-fulldeps/issue_16723_multiple_items_syntax_ext.rs

@@ -12,8 +12,7 @@
 // ignore-android
 // aux-build:issue_16723_multiple_items_syntax_ext.rs
 #![feature(plugin)]
-
-#[plugin] #[no_link] extern crate issue_16723_multiple_items_syntax_ext;
+#![plugin(issue_16723_multiple_items_syntax_ext)]
 
 multiple_items!();
 

src/test/run-pass-fulldeps/lint-group-plugin.rs

@@ -13,9 +13,7 @@
 // ignore-pretty
 
 #![feature(plugin)]
-
-#[plugin] #[no_link]
-extern crate lint_group_plugin_test;
+#![plugin(lint_group_plugin_test)]
 
 fn lintme() { } //~ WARNING item is named 'lintme'
 fn pleaselintme() { } //~ WARNING item is named 'pleaselintme'

src/test/run-pass-fulldeps/lint-plugin-cmdline-allow.rs

@@ -13,9 +13,7 @@
 // compile-flags: -A test-lint
 
 #![feature(plugin)]
-
-#[plugin] #[no_link]
-extern crate lint_plugin_test;
+#![plugin(lint_plugin_test)]
 
 fn lintme() { }
 

src/test/run-pass-fulldeps/lint-plugin.rs

@@ -13,9 +13,7 @@
 // ignore-pretty
 
 #![feature(plugin)]
-
-#[plugin] #[no_link]
-extern crate lint_plugin_test;
+#![plugin(lint_plugin_test)]
 
 fn lintme() { } //~ WARNING item is named 'lintme'
 

src/test/run-pass-fulldeps/macro-crate-does-hygiene-work.rs

@@ -15,9 +15,7 @@
 // uses `quote_expr!` to rearrange it should be hygiene-preserving.
 
 #![feature(plugin)]
-
-#[plugin] #[no_link]
-extern crate macro_crate_test;
+#![plugin(macro_crate_test)]
 
 fn main() {
     let x = 3;

src/test/run-pass-fulldeps/macro-crate-outlive-expansion-phase.rs

@@ -12,8 +12,6 @@
 // ignore-stage1
 
 #![feature(plugin)]
-
-#[plugin] #[no_link]
-extern crate plugin_crate_outlive_expansion_phase;
+#![plugin(plugin_crate_outlive_expansion_phase)]
 
 pub fn main() {}

src/test/run-pass-fulldeps/macro-crate.rs

@@ -12,8 +12,9 @@
 // ignore-stage1
 
 #![feature(plugin)]
+#![plugin(macro_crate_test)]
 
-#[macro_use] #[plugin] #[no_link]
+#[macro_use] #[no_link]
 extern crate macro_crate_test;
 
 #[into_foo]

src/test/run-pass-fulldeps/plugin-args-1.rs

@@ -12,11 +12,8 @@
 // ignore-stage1
 
 #![feature(plugin)]
-
-#[no_link]
-#[plugin]
-extern crate plugin_args;
+#![plugin(plugin_args)]
 
 fn main() {
-    assert_eq!(plugin_args!(), "#[plugin]");
+    assert_eq!(plugin_args!(), "");
 }

src/test/run-pass-fulldeps/plugin-args-2.rs

@@ -12,11 +12,8 @@
 // ignore-stage1
 
 #![feature(plugin)]
-
-#[no_link]
-#[plugin()]
-extern crate plugin_args;
+#![plugin(plugin_args())]
 
 fn main() {
-    assert_eq!(plugin_args!(), "#[plugin()]");
+    assert_eq!(plugin_args!(), "");
 }

src/test/run-pass-fulldeps/plugin-args-3.rs

@@ -12,11 +12,8 @@
 // ignore-stage1
 
 #![feature(plugin)]
-
-#[no_link]
-#[plugin(hello(there), how(are="you"))]
-extern crate plugin_args;
+#![plugin(plugin_args(hello(there), how(are="you")))]
 
 fn main() {
-    assert_eq!(plugin_args!(), "#[plugin(hello(there), how(are = \"you\"))]");
+    assert_eq!(plugin_args!(), "hello(there), how(are = \"you\")");
 }

src/test/run-pass-fulldeps/plugin-plus-extern-crate.rs

@@ -1,4 +1,4 @@
-// Copyright 2013-2014 The Rust Project Developers. See the COPYRIGHT
+// Copyright 2013-2015 The Rust Project Developers. See the COPYRIGHT
 // file at the top-level directory of this distribution and at
 // http://rust-lang.org/COPYRIGHT.
 //
@@ -16,8 +16,8 @@
 // libsyntax is not compiled for it.
 
 #![feature(plugin)]
+#![plugin(macro_crate_test)]
 
-#[plugin]
 extern crate macro_crate_test;
 
 fn main() {

src/test/run-pass-fulldeps/roman-numerals-macro.rs

@@ -12,9 +12,7 @@
 // ignore-stage1
 
 #![feature(plugin)]
-
-#[plugin] #[no_link]
-extern crate roman_numerals;
+#![plugin(roman_numerals)]
 
 pub fn main() {
     assert_eq!(rn!(MMXV), 2015);

src/test/run-pass-fulldeps/syntax-extension-with-dll-deps.rs

@@ -8,14 +8,12 @@
 // option. This file may not be copied, modified, or distributed
 // except according to those terms.
 
-// aux-build:syntax-extension-with-dll-deps-1.rs
-// aux-build:syntax-extension-with-dll-deps-2.rs
+// aux-build:syntax_extension_with_dll_deps_1.rs
+// aux-build:syntax_extension_with_dll_deps_2.rs
 // ignore-stage1
 
 #![feature(plugin)]
-
-#[plugin] #[no_link]
-extern crate "syntax-extension-with-dll-deps-2" as extension;
+#![plugin(syntax_extension_with_dll_deps_2)]
 
 fn main() {
     foo!();