Merge branch 'dropck-eyepatch' of github.com:pnkfelix/rfcs into dropck-eyepatch

Author: pnkfelix

text/1327-dropck-param-eyepatch.md

@@ -1,4 +1,4 @@
-- Feature Name: dropck_eyepatch
+- Feature Name: dropck_eyepatch, generic_param_attrs
 - Start Date: 2015-10-19
 - RFC PR: [rust-lang/rfcs#1327](https://github.com/rust-lang/rfcs/pull/1327)
 - Rust Issue: [rust-lang/rust#34761](https://github.com/rust-lang/rust/issues/34761)
@@ -19,6 +19,9 @@ and type paramters). Atop that capability, this RFC proposes adding a
 holds data that must not be accessed during the dynamic extent of that
 `drop` invocation.
 
+As a side-effect, enable adding attributes to the formal declarations
+of generic type and lifetime parameters.
+
 [RFC 1238]: https://github.com/rust-lang/rfcs/blob/master/text/1238-nonparametric-dropck.md
 [RFC 769]: https://github.com/rust-lang/rfcs/blob/master/text/0769-sound-generic-drop.md
 
@@ -140,7 +143,7 @@ storage for [cyclic graph structures][dropck_legal_cycles.rs]).
  1. Add the ability to attach attributes to syntax that binds formal
     lifetime or type parmeters. For the purposes of this RFC, the only
     place in the syntax that requires such attributes are `impl`
-    blocks, as in `impl Drop for Type { ... }`
+    blocks, as in `impl<T> Drop for Type<T> { ... }`
 
  2. Add a new fine-grained attribute, `may_dangle`, which is attached
     to the binding sites for lifetime or type parameters on an `Drop`
@@ -163,6 +166,8 @@ storage for [cyclic graph structures][dropck_legal_cycles.rs]).
 
 This is a simple extension to the syntax.
 
+It is guarded by the feature gate `generic_param_attrs`.
+
 Constructions like the following will now become legal.
 
 Example of eyepatch attribute on a single type parameter:
@@ -212,6 +217,8 @@ unsafe impl<'a, X, Y> Drop for Foo<'a, #[may_dangle] X, Y> {
 
 Add a new attribute, `#[may_dangle]` (the "eyepatch").
 
+It is guarded by the feature gate `dropck_eyepatch`.
+
 The eyepatch is similar to `unsafe_destructor_blind_to_params`: it is
 part of the `Drop` implementation, and it is meant
 to assert that a destructor is guaranteed not to access certain kinds
@@ -457,10 +464,6 @@ reflected in what he wrote in the [RFC 1238 alternatives][].)
 
 ## Make dropck "see again" via (focused) where-clauses
 
-(This alternative carries over some ideas from
-[the previous section][blacklist-not-whitelist], but it stands well on
-its own as something to consider, so I am giving it its own section.)
-
 The idea is that we keep the UGEH attribute, blunt hammer that it is.
 You first opt out of the dropck ordering constraints via that, and
 then you add back in ordering constraints via `where` clauses.