remove Clone from FnCtxt

Author: nikomatsakis

src/librustc_typeck/check/coercion.rs

@@ -914,7 +914,6 @@ impl<'a, 'gcx, 'tcx> FnCtxt<'a, 'gcx, 'tcx> {
 /// }
 /// let final_ty = coerce.complete(fcx);
 /// ```
-#[derive(Clone)] // (*)
 pub struct CoerceMany<'gcx, 'tcx, 'exprs, E>
     where 'gcx: 'tcx, E: 'exprs + AsCoercionSite,
 {
@@ -928,16 +927,13 @@ pub struct CoerceMany<'gcx, 'tcx, 'exprs, E>
 /// a buffer. We use this in `check/mod.rs` for things like `break`.
 pub type DynamicCoerceMany<'gcx, 'tcx> = CoerceMany<'gcx, 'tcx, 'gcx, P<hir::Expr>>;
 
-#[derive(Clone)] // (*)
 enum Expressions<'gcx, 'exprs, E>
     where E: 'exprs + AsCoercionSite,
 {
     Dynamic(Vec<&'gcx hir::Expr>),
     UpFront(&'exprs [E]),
 }
 
-// (*) this is clone because `FnCtxt` is clone, but it seems dubious -- nmatsakis
-
 impl<'gcx, 'tcx, 'exprs, E> CoerceMany<'gcx, 'tcx, 'exprs, E>
     where 'gcx: 'tcx, E: 'exprs + AsCoercionSite,
 {

src/librustc_typeck/check/mod.rs

@@ -415,7 +415,6 @@ impl Diverges {
     }
 }
 
-#[derive(Clone)]
 pub struct BreakableCtxt<'gcx: 'tcx, 'tcx> {
     may_break: bool,
 
@@ -424,7 +423,6 @@ pub struct BreakableCtxt<'gcx: 'tcx, 'tcx> {
     coerce: Option<DynamicCoerceMany<'gcx, 'tcx>>,
 }
 
-#[derive(Clone)]
 pub struct EnclosingBreakables<'gcx: 'tcx, 'tcx> {
     stack: Vec<BreakableCtxt<'gcx, 'tcx>>,
     by_id: NodeMap<usize>,
@@ -439,7 +437,6 @@ impl<'gcx, 'tcx> EnclosingBreakables<'gcx, 'tcx> {
     }
 }
 
-#[derive(Clone)]
 pub struct FnCtxt<'a, 'gcx: 'a+'tcx, 'tcx: 'a> {
     ast_ty_to_ty_cache: RefCell<NodeMap<Ty<'tcx>>>,