Auto merge of #23137 - kmcallister:derive-sugar, r=sfackler

This is a hack, but I don't think we can do much better as long as `derive` is running at the syntax expansion phase.

If the `custom_derive` feature gate is enabled, this works with user-defined traits and syntax extensions. Without the gate, you can't use e.g. `#[derive_Clone]` directly, so this does not change the stable language.

To make this effective, we now check gated attributes both before and after macro expansion. This uncovered a number of tests that were missing feature gates.

This PR also cleans up the deriving code somewhat, and forbids some previously-meaningless attribute syntax. For this reason it's technically a

    [breaking-change]

r? @sfackler

src/test/auxiliary/custom_derive_plugin.rs

@@ -0,0 +1,74 @@
+// 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.
+
+// force-host
+
+#![feature(plugin_registrar)]
+#![feature(box_syntax)]
+#![feature(rustc_private)]
+
+extern crate syntax;
+extern crate rustc;
+
+use syntax::ast;
+use syntax::codemap::Span;
+use syntax::ext::base::{Decorator, ExtCtxt};
+use syntax::ext::build::AstBuilder;
+use syntax::ext::deriving::generic::{cs_fold, TraitDef, MethodDef, combine_substructure};
+use syntax::ext::deriving::generic::ty::{Literal, LifetimeBounds, Path, borrowed_explicit_self};
+use syntax::parse::token;
+use syntax::ptr::P;
+use rustc::plugin::Registry;
+
+#[plugin_registrar]
+pub fn plugin_registrar(reg: &mut Registry) {
+    reg.register_syntax_extension(
+        token::intern("derive_TotalSum"),
+        Decorator(box expand));
+}
+
+fn expand(cx: &mut ExtCtxt,
+          span: Span,
+          mitem: &ast::MetaItem,
+          item: &ast::Item,
+          push: &mut FnMut(P<ast::Item>)) {
+    let trait_def = TraitDef {
+        span: span,
+        attributes: vec![],
+        path: Path::new(vec!["TotalSum"]),
+        additional_bounds: vec![],
+        generics: LifetimeBounds::empty(),
+        associated_types: vec![],
+        methods: vec![
+            MethodDef {
+                name: "total_sum",
+                generics: LifetimeBounds::empty(),
+                explicit_self: borrowed_explicit_self(),
+                args: vec![],
+                ret_ty: Literal(Path::new_local("isize")),
+                attributes: vec![],
+                combine_substructure: combine_substructure(box |cx, span, substr| {
+                    let zero = cx.expr_int(span, 0);
+                    cs_fold(false,
+                            |cx, span, subexpr, field, _| {
+                                cx.expr_binary(span, ast::BiAdd, subexpr,
+                                    cx.expr_method_call(span, field,
+                                        token::str_to_ident("total_sum"), vec![]))
+                            },
+                            zero,
+                            box |cx, span, _, _| { cx.span_bug(span, "wtf??"); },
+                            cx, span, substr)
+                }),
+            },
+        ],
+    };
+
+    trait_def.expand(cx, mitem, item, |i| push(i))
+}

src/test/compile-fail/deprecated-phase.rs

@@ -8,6 +8,8 @@
 // option. This file may not be copied, modified, or distributed
 // except according to those terms.
 
+#![feature(custom_attribute)]
+
 #[phase(blah)]
 //~^ ERROR #[phase] is deprecated
 extern crate foo;

src/test/compile-fail/deriving-bounds.rs

@@ -8,12 +8,12 @@
 // option. This file may not be copied, modified, or distributed
 // except according to those terms.
 
-#[derive(Copy(Bad))]
-//~^ ERROR unexpected value in deriving, expected a trait
+#[derive(Send)]
+//~^ ERROR this unsafe trait should be implemented explicitly
 struct Test;
 
 #[derive(Sync)]
-//~^ ERROR Sync is an unsafe trait and it should be implemented explicitly
+//~^ ERROR this unsafe trait should be implemented explicitly
 struct Test1;
 
 pub fn main() {}

src/test/compile-fail/deriving-meta-unknown-trait.rs

@@ -8,7 +8,8 @@
 // option. This file may not be copied, modified, or distributed
 // except according to those terms.
 
-#[derive(Eqr)] //~ ERROR unknown `derive` trait: `Eqr`
+#[derive(Eqr)]
+//~^ ERROR `#[derive]` for custom traits is not stable enough for use and is subject to change
 struct Foo;
 
 pub fn main() {}

src/test/compile-fail/feature-gate-intrinsics.rs

@@ -8,9 +8,6 @@
 // option. This file may not be copied, modified, or distributed
 // except according to those terms.
 
-#[lang="foo"]   //~ ERROR language items are subject to change
-trait Foo {}
-
 extern "rust-intrinsic" {   //~ ERROR intrinsics are subject to change
     fn bar();
 }
@@ -20,4 +17,3 @@ extern "rust-intrinsic" fn baz() {  //~ ERROR intrinsics are subject to change
 
 fn main() {
 }
-

src/test/compile-fail/feature-gate-lang-items.rs

@@ -0,0 +1,15 @@
+// Copyright 2014 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.
+
+#[lang="foo"]   //~ ERROR language items are subject to change
+trait Foo {}
+
+fn main() {
+}

src/test/compile-fail/linkage1.rs

@@ -11,5 +11,4 @@
 extern {
     #[linkage = "extern_weak"] static foo: isize;
     //~^ ERROR: the `linkage` attribute is experimental and not portable
-    //~^^ ERROR: the `linkage` attribute is experimental and not portable
 }

src/test/compile-fail/malformed-derive-entry.rs

@@ -0,0 +1,25 @@
+// 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.
+
+#[derive(Copy(Bad))]
+//~^ ERROR malformed `derive` entry
+struct Test1;
+
+#[derive(Copy="bad")]
+//~^ ERROR malformed `derive` entry
+struct Test2;
+
+#[derive()]
+//~^ WARNING empty trait list
+struct Test3;
+
+#[derive]
+//~^ WARNING empty trait list
+struct Test4;

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

@@ -8,6 +8,7 @@
 // option. This file may not be copied, modified, or distributed
 // except according to those terms.
 
+#![feature(plugin)]
 #![plugin] //~ ERROR malformed plugin attribute
 
 fn main() {}

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

@@ -8,6 +8,7 @@
 // option. This file may not be copied, modified, or distributed
 // except according to those terms.
 
+#![feature(plugin)]
 #![plugin="bleh"] //~ ERROR malformed plugin attribute
 
 fn main() {}

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

@@ -8,6 +8,7 @@
 // option. This file may not be copied, modified, or distributed
 // except according to those terms.
 
+#![feature(plugin)]
 #![plugin(foo="bleh")] //~ ERROR malformed plugin attribute
 
 fn main() {}

src/test/compile-fail/plugin-extern-crate-attr-deprecated.rs

@@ -8,6 +8,8 @@
 // option. This file may not be copied, modified, or distributed
 // except according to those terms.
 
+#![feature(plugin)]
+
 #[plugin]  //~ ERROR #[plugin] on `extern crate` is deprecated
 //~^ HELP use a crate attribute instead, i.e. #![plugin(std)]
 extern crate std;

src/test/compile-fail/reserved-attr-on-macro.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.
+
+#[rustc_attribute_should_be_reserved] //~ ERROR attributes with the prefix `rustc_` are reserved
+macro_rules! foo {
+    () => (());
+}
+
+fn main() {
+    foo!();
+}

src/test/compile-fail/single-derive-attr.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.
+
+#[derive_Clone]
+//~^ ERROR attributes of the form `#[derive_*]` are reserved
+struct Test;
+
+pub fn main() {}

src/test/run-pass-fulldeps/derive-totalsum.rs

@@ -0,0 +1,59 @@
+// 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:custom_derive_plugin.rs
+// ignore-stage1
+
+#![feature(plugin, custom_derive)]
+#![plugin(custom_derive_plugin)]
+
+trait TotalSum {
+    fn total_sum(&self) -> isize;
+}
+
+impl TotalSum for isize {
+    fn total_sum(&self) -> isize {
+        *self
+    }
+}
+
+struct Seven;
+
+impl TotalSum for Seven {
+    fn total_sum(&self) -> isize {
+        7
+    }
+}
+
+#[derive(TotalSum)]
+struct Foo {
+    seven: Seven,
+    bar: Bar,
+    baz: isize,
+}
+
+#[derive(TotalSum)]
+struct Bar {
+    quux: isize,
+    bleh: isize,
+}
+
+
+pub fn main() {
+    let v = Foo {
+        seven: Seven,
+        bar: Bar {
+            quux: 9,
+            bleh: 3,
+        },
+        baz: 80,
+    };
+    assert_eq!(v.total_sum(), 99);
+}

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

@@ -11,7 +11,7 @@
 // aux-build:macro_crate_test.rs
 // ignore-stage1
 
-#![feature(plugin)]
+#![feature(plugin, custom_attribute)]
 #![plugin(macro_crate_test)]
 
 #[macro_use] #[no_link]

src/test/run-pass/deprecated-derive.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.
+
+#[derive(Show)]
+//~^ WARNING derive(Show) is deprecated
+struct Test1;
+
+fn main() { }

src/test/run-pass/single-derive-attr-with-gate.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.
+
+#![feature(custom_derive)]
+
+#[derive_Clone]
+struct Test;
+
+pub fn main() {
+    Test.clone();
+}