auto merge of #19683 : nikomatsakis/rust/generalized-where-clauses, r=nrc

This patch does not itself enable generalized where clauses, but it lays the groundwork. Rather than storing a list of bounds per type parameter, the trait selection and other logic is now driven by a unified list of predicates. All predicate handling is now driven through a common interface. This also fixes a number of bugs where region predicates were being dropped on the floor. As a drive-by, this patch also fixes some bugs in the opt-out-copy feature flag.

That said, this patch does not change the parser or AST in any way, so we still *generate* the list of predicates by walking a list of bounds (and we still *store* the bounds on the `TypeParameterDef` and so on). Those will get patched in a follow-up.

The commits in this case are standalone; the first few are simple refactorings.

r? @nick29581 
cc @aturon 

1 files changed, 1 insertions, 1 deletions

diff --git a/src/libcore/kinds.rs b/src/libcore/kinds.rs
index f932acffd3c..2b92ae8af0a 100644
--- a/src/libcore/kinds.rs
+++ b/src/libcore/kinds.rs
@@ -19,7 +19,7 @@
 
 /// Types able to be transferred across task boundaries.
 #[lang="send"]
-pub trait Send for Sized? {
+pub trait Send for Sized? : 'static {
     // empty.
 }