auto trait future compatibility lint

Author: leoyvens

src/libcore/marker.rs

@@ -46,6 +46,8 @@ pub unsafe trait Send {
 }
 
 #[stable(feature = "rust1", since = "1.0.0")]
+#[allow(unknown_lints)]
+#[allow(auto_impl)]
 unsafe impl Send for .. { }
 
 #[stable(feature = "rust1", since = "1.0.0")]
@@ -349,6 +351,8 @@ pub unsafe trait Sync {
 }
 
 #[stable(feature = "rust1", since = "1.0.0")]
+#[allow(unknown_lints)]
+#[allow(auto_impl)]
 unsafe impl Sync for .. { }
 
 #[stable(feature = "rust1", since = "1.0.0")]
@@ -562,6 +566,8 @@ mod impls {
 #[lang = "freeze"]
 unsafe trait Freeze {}
 
+#[allow(unknown_lints)]
+#[allow(auto_impl)]
 unsafe impl Freeze for .. {}
 
 impl<T: ?Sized> !Freeze for UnsafeCell<T> {}

src/librustc_lint/builtin.rs

@@ -55,6 +55,31 @@ use bad_style::{MethodLateContext, method_context};
 // hardwired lints from librustc
 pub use lint::builtin::*;
 
+declare_lint! {
+    pub AUTO_IMPL,
+    Deny,
+    "The form `impl Foo for .. {}` will be removed, please use `auto trait Foo {}`"
+}
+
+#[derive(Copy, Clone)]
+pub struct AutoImpl;
+
+impl LintPass for AutoImpl {
+    fn get_lints(&self) -> LintArray {
+        lint_array!(AUTO_IMPL)
+    }
+}
+
+impl EarlyLintPass for AutoImpl {
+    fn check_item(&mut self, cx: &EarlyContext, item: &ast::Item) {
+        let msg = "The form `impl Foo for .. {}` will be removed, please use `auto trait Foo {}`";
+        match item.node {
+            ast::ItemKind::AutoImpl(..) => cx.span_lint(AUTO_IMPL, item.span, msg),
+            _ => ()
+        }
+     }
+}
+
 declare_lint! {
     WHILE_TRUE,
     Warn,

src/librustc_lint/lib.rs

@@ -109,6 +109,7 @@ pub fn register_builtins(store: &mut lint::LintStore, sess: Option<&Session>) {
                        AnonymousParameters,
                        IllegalFloatLiteralPattern,
                        UnusedDocComment,
+                       AutoImpl,
                        );
 
     add_early_builtin_with_new!(sess,
@@ -181,6 +182,10 @@ pub fn register_builtins(store: &mut lint::LintStore, sess: Option<&Session>) {
     // - Eventually, remove lint
     store.register_future_incompatible(sess,
                                        vec![
+        FutureIncompatibleInfo {
+            id: LintId::of(AUTO_IMPL),
+            reference: "issue #13231 <https://github.com/rust-lang/rust/issues/13231>",
+        },
         FutureIncompatibleInfo {
             id: LintId::of(PRIVATE_IN_PUBLIC),
             reference: "issue #34537 <https://github.com/rust-lang/rust/issues/34537>",

src/libstd/panic.rs

@@ -188,6 +188,8 @@ pub struct AssertUnwindSafe<T>(
 // * Types like Mutex/RwLock which are explicilty poisoned are unwind safe
 // * Our custom AssertUnwindSafe wrapper is indeed unwind safe
 #[stable(feature = "catch_unwind", since = "1.9.0")]
+#[allow(unknown_lints)]
+#[allow(auto_impl)]
 impl UnwindSafe for .. {}
 #[stable(feature = "catch_unwind", since = "1.9.0")]
 impl<'a, T: ?Sized> !UnwindSafe for &'a mut T {}
@@ -221,6 +223,8 @@ impl<T: RefUnwindSafe + ?Sized> UnwindSafe for Arc<T> {}
 // only thing which doesn't implement it (which then transitively applies to
 // everything else).
 #[stable(feature = "catch_unwind", since = "1.9.0")]
+#[allow(unknown_lints)]
+#[allow(auto_impl)]
 impl RefUnwindSafe for .. {}
 #[stable(feature = "catch_unwind", since = "1.9.0")]
 impl<T: ?Sized> !RefUnwindSafe for UnsafeCell<T> {}

src/rtstartup/rsbegin.rs

@@ -14,7 +14,7 @@
 // When an executable or dylib image is linked, all user code and libraries are
 // "sandwiched" between these two object files, so code or data from rsbegin.o
 // become first in the respective sections of the image, whereas code and data
-// from rsend.o become the last ones.  This effect can be used to place symbols
+// from rsend.o become the last ones. This effect can be used to place symbols
 // at the beginning or at the end of a section, as well as to insert any required
 // headers or footers.
 //
@@ -31,11 +31,15 @@
 trait Sized {}
 #[lang = "sync"]
 trait Sync {}
+#[allow(unknown_lints)]
+#[allow(auto_impl)]
 impl Sync for .. {}
 #[lang = "copy"]
 trait Copy {}
 #[lang = "freeze"]
 trait Freeze {}
+#[allow(unknown_lints)]
+#[allow(auto_impl)]
 impl Freeze for .. {}
 
 #[lang = "drop_in_place"]

src/rtstartup/rsend.rs

@@ -23,6 +23,8 @@ impl<T> Sync for T {}
 trait Copy {}
 #[lang = "freeze"]
 trait Freeze {}
+#[allow(unknown_lints)]
+#[allow(auto_impl)]
 impl Freeze for .. {}
 
 #[lang = "drop_in_place"]

src/test/compile-fail/auto-impl-future-compat.rs

@@ -0,0 +1,12 @@
+// Copyright 2017 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.
+
+trait Foo {}
+impl Foo for .. {}

src/test/compile-fail/coherence-default-trait-impl.rs

@@ -12,18 +12,22 @@
 
 trait MyTrait { fn foo() {} }
 
+#[allow(auto_impl)]
 impl MyTrait for .. {}
 //~^ ERROR redundant auto implementations of trait `MyTrait`
 
+#[allow(auto_impl)]
 impl MyTrait for .. {}
 
 trait MySafeTrait {}
 
+#[allow(auto_impl)]
 unsafe impl MySafeTrait for .. {}
 //~^ ERROR implementing the trait `MySafeTrait` is not unsafe
 
 unsafe trait MyUnsafeTrait {}
 
+#[allow(auto_impl)]
 impl MyUnsafeTrait for .. {}
 //~^ ERROR the trait `MyUnsafeTrait` requires an `unsafe impl` declaration
 

src/test/compile-fail/feature-gate-optin-builtin-traits.rs

@@ -20,6 +20,7 @@ trait DummyTrait {
 auto trait AutoDummyTrait {}
 //~^ ERROR auto traits are experimental and possibly buggy
 
+#[allow(auto_impl)]
 impl DummyTrait for .. {}
 //~^ ERROR auto trait implementations are experimental and possibly buggy
 

src/test/compile-fail/issue-23080-2.rs

@@ -17,6 +17,7 @@ unsafe trait Trait {
     type Output;
 }
 
+#[allow(auto_impl)]
 unsafe impl Trait for .. {}
 
 fn call_method<T: Trait>(x: T) {}