Rollup merge of #64874 - matthewjasper:simplify-euv, r=eddyb

Simplify ExprUseVisitor

* Remove HIR const qualification
* Remove parts of ExprUseVisitor that aren't being used

r? @eddyb

19 files changed, 149 insertions, 1344 deletions

diff --git a/src/librustc/middle/expr_use_visitor.rs b/src/librustc/middle/expr_use_visitor.rs
index 45b660f5c67..bb7ac5d8dbe 100644
--- a/src/librustc/middle/expr_use_visitor.rs
+++ b/src/librustc/middle/expr_use_visitor.rs
@@ -2,25 +2,20 @@
 //! normal visitor, which just walks the entire body in one shot, the
 //! `ExprUseVisitor` determines how expressions are being used.
 
-pub use self::LoanCause::*;
 pub use self::ConsumeMode::*;
-pub use self::MoveReason::*;
-pub use self::MatchMode::*;
-use self::TrackMatchMode::*;
 use self::OverloadedCallType::*;
 
-use crate::hir::def::{CtorOf, Res, DefKind};
+use crate::hir::def::Res;
 use crate::hir::def_id::DefId;
 use crate::hir::ptr::P;
 use crate::infer::InferCtxt;
 use crate::middle::mem_categorization as mc;
 use crate::middle::region;
-use crate::ty::{self, DefIdTree, TyCtxt, adjustment};
+use crate::ty::{self, TyCtxt, adjustment};
 
 use crate::hir::{self, PatKind};
 use std::rc::Rc;
 use syntax_pos::Span;
-use crate::util::nodemap::ItemLocalSet;
 
 ///////////////////////////////////////////////////////////////////////////
 // The Delegate trait
@@ -30,161 +25,19 @@ use crate::util::nodemap::ItemLocalSet;
 pub trait Delegate<'tcx> {
     // The value found at `cmt` is either copied or moved, depending
     // on mode.
-    fn consume(&mut self,
-               consume_id: hir::HirId,
-               consume_span: Span,
-               cmt: &mc::cmt_<'tcx>,
-               mode: ConsumeMode);
-
-    // The value found at `cmt` has been determined to match the
-    // pattern binding `matched_pat`, and its subparts are being
-    // copied or moved depending on `mode`.  Note that `matched_pat`
-    // is called on all variant/structs in the pattern (i.e., the
-    // interior nodes of the pattern's tree structure) while
-    // consume_pat is called on the binding identifiers in the pattern
-    // (which are leaves of the pattern's tree structure).
-    //
-    // Note that variants/structs and identifiers are disjoint; thus
-    // `matched_pat` and `consume_pat` are never both called on the
-    // same input pattern structure (though of `consume_pat` can be
-    // called on a subpart of an input passed to `matched_pat).
-    fn matched_pat(&mut self,
-                   matched_pat: &hir::Pat,
-                   cmt: &mc::cmt_<'tcx>,
-                   mode: MatchMode);
-
-    // The value found at `cmt` is either copied or moved via the
-    // pattern binding `consume_pat`, depending on mode.
-    fn consume_pat(&mut self,
-                   consume_pat: &hir::Pat,
-                   cmt: &mc::cmt_<'tcx>,
-                   mode: ConsumeMode);
-
-    // The value found at `borrow` is being borrowed at the point
-    // `borrow_id` for the region `loan_region` with kind `bk`.
-    fn borrow(&mut self,
-              borrow_id: hir::HirId,
-              borrow_span: Span,
-              cmt: &mc::cmt_<'tcx>,
-              loan_region: ty::Region<'tcx>,
-              bk: ty::BorrowKind,
-              loan_cause: LoanCause);
-
-    // The local variable `id` is declared but not initialized.
-    fn decl_without_init(&mut self,
-                         id: hir::HirId,
-                         span: Span);
+    fn consume(&mut self, cmt: &mc::cmt_<'tcx>, mode: ConsumeMode);
 
-    // The path at `cmt` is being assigned to.
-    fn mutate(&mut self,
-              assignment_id: hir::HirId,
-              assignment_span: Span,
-              assignee_cmt: &mc::cmt_<'tcx>,
-              mode: MutateMode);
-
-    // A nested closure or generator - only one layer deep.
-    fn nested_body(&mut self, _body_id: hir::BodyId) {}
-}
+    // The value found at `cmt` is being borrowed with kind `bk`.
+    fn borrow(&mut self, cmt: &mc::cmt_<'tcx>, bk: ty::BorrowKind);
 
-#[derive(Copy, Clone, PartialEq, Debug)]
-pub enum LoanCause {
-    ClosureCapture(Span),
-    AddrOf,
-    AutoRef,
-    AutoUnsafe,
-    RefBinding,
-    OverloadedOperator,
-    ClosureInvocation,
-    ForLoop,
-    MatchDiscriminant
+    // The path at `cmt` is being assigned to.
+    fn mutate(&mut self, assignee_cmt: &mc::cmt_<'tcx>);
 }
 
 #[derive(Copy, Clone, PartialEq, Debug)]
 pub enum ConsumeMode {
     Copy,                // reference to x where x has a type that copies
-    Move(MoveReason),    // reference to x where x has a type that moves
-}
-
-#[derive(Copy, Clone, PartialEq, Debug)]
-pub enum MoveReason {
-    DirectRefMove,
-    PatBindingMove,
-    CaptureMove,
-}
-
-#[derive(Copy, Clone, PartialEq, Debug)]
-pub enum MatchMode {
-    NonBindingMatch,
-    BorrowingMatch,
-    CopyingMatch,
-    MovingMatch,
-}
-
-#[derive(Copy, Clone, PartialEq, Debug)]
-enum TrackMatchMode {
-    Unknown,
-    Definite(MatchMode),
-    Conflicting,
-}
-
-impl TrackMatchMode {
-    // Builds up the whole match mode for a pattern from its constituent
-    // parts.  The lattice looks like this:
-    //
-    //          Conflicting
-    //            /     \
-    //           /       \
-    //      Borrowing   Moving
-    //           \       /
-    //            \     /
-    //            Copying
-    //               |
-    //          NonBinding
-    //               |
-    //            Unknown
-    //
-    // examples:
-    //
-    // * `(_, some_int)` pattern is Copying, since
-    //   NonBinding + Copying => Copying
-    //
-    // * `(some_int, some_box)` pattern is Moving, since
-    //   Copying + Moving => Moving
-    //
-    // * `(ref x, some_box)` pattern is Conflicting, since
-    //   Borrowing + Moving => Conflicting
-    //
-    // Note that the `Unknown` and `Conflicting` states are
-    // represented separately from the other more interesting
-    // `Definite` states, which simplifies logic here somewhat.
-    fn lub(&mut self, mode: MatchMode) {
-        *self = match (*self, mode) {
-            // Note that clause order below is very significant.
-            (Unknown, new) => Definite(new),
-            (Definite(old), new) if old == new => Definite(old),
-
-            (Definite(old), NonBindingMatch) => Definite(old),
-            (Definite(NonBindingMatch), new) => Definite(new),
-
-            (Definite(old), CopyingMatch) => Definite(old),
-            (Definite(CopyingMatch), new) => Definite(new),
-
-            (Definite(_), _) => Conflicting,
-            (Conflicting, _) => *self,
-        };
-    }
-
-    fn match_mode(&self) -> MatchMode {
-        match *self {
-            Unknown => NonBindingMatch,
-            Definite(mode) => mode,
-            Conflicting => {
-                // Conservatively return MovingMatch to let the
-                // compiler continue to make progress.
-                MovingMatch
-            }
-        }
-    }
+    Move,                // reference to x where x has a type that moves
 }
 
 #[derive(Copy, Clone, PartialEq, Debug)]
@@ -261,9 +114,6 @@ impl<'a, 'tcx> ExprUseVisitor<'a, 'tcx> {
     /// - `param_env` --- parameter environment for trait lookups (esp. pertaining to `Copy`)
     /// - `region_scope_tree` --- region scope tree for the code being analyzed
     /// - `tables` --- typeck results for the code being analyzed
-    /// - `rvalue_promotable_map` --- if you care about rvalue promotion, then provide
-    ///   the map here (it can be computed with `tcx.rvalue_promotable_map(def_id)`).
-    ///   `None` means that rvalues will be given more conservative lifetimes.
     ///
     /// See also `with_infer`, which is used *during* typeck.
     pub fn new(
@@ -273,15 +123,13 @@ impl<'a, 'tcx> ExprUseVisitor<'a, 'tcx> {
         param_env: ty::ParamEnv<'tcx>,
         region_scope_tree: &'a region::ScopeTree,
         tables: &'a ty::TypeckTables<'tcx>,
-        rvalue_promotable_map: Option<&'tcx ItemLocalSet>,
     ) -> Self {
         ExprUseVisitor {
             mc: mc::MemCategorizationContext::new(tcx,
                                                   param_env,
                                                   body_owner,
                                                   region_scope_tree,
-                                                  tables,
-                                                  rvalue_promotable_map),
+                                                  tables),
             delegate,
             param_env,
         }
@@ -317,16 +165,9 @@ impl<'a, 'tcx> ExprUseVisitor<'a, 'tcx> {
             let param_ty = return_if_err!(self.mc.pat_ty_adjusted(&param.pat));
             debug!("consume_body: param_ty = {:?}", param_ty);
 
-            let fn_body_scope_r =
-                self.tcx().mk_region(ty::ReScope(
-                    region::Scope {
-                        id: body.value.hir_id.local_id,
-                        data: region::ScopeData::Node
-                }));
             let param_cmt = Rc::new(self.mc.cat_rvalue(
                 param.hir_id,
                 param.pat.span,
-                fn_body_scope_r, // Parameters live only as long as the fn body.
                 param_ty));
 
             self.walk_irrefutable_pat(param_cmt, &param.pat);
@@ -339,15 +180,11 @@ impl<'a, 'tcx> ExprUseVisitor<'a, 'tcx> {
         self.mc.tcx
     }
 
-    fn delegate_consume(&mut self,
-                        consume_id: hir::HirId,
-                        consume_span: Span,
-                        cmt: &mc::cmt_<'tcx>) {
-        debug!("delegate_consume(consume_id={}, cmt={:?})",
-               consume_id, cmt);
+    fn delegate_consume(&mut self, cmt: &mc::cmt_<'tcx>) {
+        debug!("delegate_consume(cmt={:?})", cmt);
 
-        let mode = copy_or_move(&self.mc, self.param_env, cmt, DirectRefMove);
-        self.delegate.consume(consume_id, consume_span, cmt, mode);
+        let mode = copy_or_move(&self.mc, self.param_env, cmt);
+        self.delegate.consume(cmt, mode);
     }
 
     fn consume_exprs(&mut self, exprs: &[hir::Expr]) {
@@ -360,30 +197,21 @@ impl<'a, 'tcx> ExprUseVisitor<'a, 'tcx> {
         debug!("consume_expr(expr={:?})", expr);
 
         let cmt = return_if_err!(self.mc.cat_expr(expr));
-        self.delegate_consume(expr.hir_id, expr.span, &cmt);
+        self.delegate_consume(&cmt);
         self.walk_expr(expr);
     }
 
-    fn mutate_expr(&mut self,
-                   span: Span,
-                   assignment_expr: &hir::Expr,
-                   expr: &hir::Expr,
-                   mode: MutateMode) {
+    fn mutate_expr(&mut self, expr: &hir::Expr) {
         let cmt = return_if_err!(self.mc.cat_expr(expr));
-        self.delegate.mutate(assignment_expr.hir_id, span, &cmt, mode);
+        self.delegate.mutate(&cmt);
         self.walk_expr(expr);
     }
 
-    fn borrow_expr(&mut self,
-                   expr: &hir::Expr,
-                   r: ty::Region<'tcx>,
-                   bk: ty::BorrowKind,
-                   cause: LoanCause) {
-        debug!("borrow_expr(expr={:?}, r={:?}, bk={:?})",
-               expr, r, bk);
+    fn borrow_expr(&mut self, expr: &hir::Expr, bk: ty::BorrowKind) {
+        debug!("borrow_expr(expr={:?}, bk={:?})", expr, bk);
 
         let cmt = return_if_err!(self.mc.cat_expr(expr));
-        self.delegate.borrow(expr.hir_id, expr.span, &cmt, r, bk, cause);
+        self.delegate.borrow(&cmt, bk);
 
         self.walk_expr(expr)
     }
@@ -401,24 +229,24 @@ impl<'a, 'tcx> ExprUseVisitor<'a, 'tcx> {
             hir::ExprKind::Path(_) => { }
 
             hir::ExprKind::Type(ref subexpr, _) => {
-                self.walk_expr(&subexpr)
+                self.walk_expr(subexpr)
             }
 
             hir::ExprKind::Unary(hir::UnDeref, ref base) => { // *base
-                self.select_from_expr(&base);
+                self.select_from_expr(base);
             }
 
             hir::ExprKind::Field(ref base, _) => { // base.f
-                self.select_from_expr(&base);
+                self.select_from_expr(base);
             }
 
             hir::ExprKind::Index(ref lhs, ref rhs) => { // lhs[rhs]
-                self.select_from_expr(&lhs);
-                self.consume_expr(&rhs);
+                self.select_from_expr(lhs);
+                self.consume_expr(rhs);
             }
 
             hir::ExprKind::Call(ref callee, ref args) => { // callee(args)
-                self.walk_callee(expr, &callee);
+                self.walk_callee(expr, callee);
                 self.consume_exprs(args);
             }
 
@@ -436,14 +264,11 @@ impl<'a, 'tcx> ExprUseVisitor<'a, 'tcx> {
 
             hir::ExprKind::Match(ref discr, ref arms, _) => {
                 let discr_cmt = Rc::new(return_if_err!(self.mc.cat_expr(&discr)));
-                let r = self.tcx().lifetimes.re_empty;
-                self.borrow_expr(&discr, r, ty::ImmBorrow, MatchDiscriminant);
+                self.borrow_expr(&discr, ty::ImmBorrow);
 
                 // treatment of the discriminant is handled while walking the arms.
                 for arm in arms {
-                    let mode = self.arm_move_mode(discr_cmt.clone(), arm);
-                    let mode = mode.match_mode();
-                    self.walk_arm(discr_cmt.clone(), arm, mode);
+                    self.walk_arm(discr_cmt.clone(), arm);
                 }
             }
 
@@ -454,11 +279,8 @@ impl<'a, 'tcx> ExprUseVisitor<'a, 'tcx> {
             hir::ExprKind::AddrOf(m, ref base) => {   // &base
                 // make sure that the thing we are pointing out stays valid
                 // for the lifetime `scope_r` of the resulting ptr:
-                let expr_ty = return_if_err!(self.mc.expr_ty(expr));
-                if let ty::Ref(r, _, _) = expr_ty.kind {
-                    let bk = ty::BorrowKind::from_mutbl(m);
-                    self.borrow_expr(&base, r, bk, AddrOf);
-                }
+                let bk = ty::BorrowKind::from_mutbl(m);
+                self.borrow_expr(&base, bk);
             }
 
             hir::ExprKind::InlineAsm(ref ia, ref outputs, ref inputs) => {
@@ -466,16 +288,7 @@ impl<'a, 'tcx> ExprUseVisitor<'a, 'tcx> {
                     if o.is_indirect {
                         self.consume_expr(output);
                     } else {
-                        self.mutate_expr(
-                            output.span,
-                            expr,
-                            output,
-                            if o.is_rw {
-                                MutateMode::WriteAndRead
-                            } else {
-                                MutateMode::JustWrite
-                            },
-                        );
+                        self.mutate_expr(output);
                     }
                 }
                 self.consume_exprs(inputs);
@@ -486,65 +299,64 @@ impl<'a, 'tcx> ExprUseVisitor<'a, 'tcx> {
             hir::ExprKind::Err => {}
 
             hir::ExprKind::Loop(ref blk, _, _) => {
-                self.walk_block(&blk);
+                self.walk_block(blk);
             }
 
             hir::ExprKind::Unary(_, ref lhs) => {
-                self.consume_expr(&lhs);
+                self.consume_expr(lhs);
             }
 
             hir::ExprKind::Binary(_, ref lhs, ref rhs) => {
-                self.consume_expr(&lhs);
-                self.consume_expr(&rhs);
+                self.consume_expr(lhs);
+                self.consume_expr(rhs);
             }
 
             hir::ExprKind::Block(ref blk, _) => {
-                self.walk_block(&blk);
+                self.walk_block(blk);
             }
 
             hir::ExprKind::Break(_, ref opt_expr) | hir::ExprKind::Ret(ref opt_expr) => {
                 if let Some(ref expr) = *opt_expr {
-                    self.consume_expr(&expr);
+                    self.consume_expr(expr);
                 }
             }
 
             hir::ExprKind::Assign(ref lhs, ref rhs) => {
-                self.mutate_expr(expr.span, expr, &lhs, MutateMode::JustWrite);
-                self.consume_expr(&rhs);
+                self.mutate_expr(lhs);
+                self.consume_expr(rhs);
             }
 
             hir::ExprKind::Cast(ref base, _) => {
-                self.consume_expr(&base);
+                self.consume_expr(base);
             }
 
             hir::ExprKind::DropTemps(ref expr) => {
-                self.consume_expr(&expr);
+                self.consume_expr(expr);
             }
 
             hir::ExprKind::AssignOp(_, ref lhs, ref rhs) => {
                 if self.mc.tables.is_method_call(expr) {
                     self.consume_expr(lhs);
                 } else {
-                    self.mutate_expr(expr.span, expr, &lhs, MutateMode::WriteAndRead);
+                    self.mutate_expr(lhs);
                 }
-                self.consume_expr(&rhs);
+                self.consume_expr(rhs);
             }
 
             hir::ExprKind::Repeat(ref base, _) => {
-                self.consume_expr(&base);
+                self.consume_expr(base);
             }
 
-            hir::ExprKind::Closure(_, _, body_id, fn_decl_span, _) => {
-                self.delegate.nested_body(body_id);
+            hir::ExprKind::Closure(_, _, _, fn_decl_span, _) => {
                 self.walk_captures(expr, fn_decl_span);
             }
 
             hir::ExprKind::Box(ref base) => {
-                self.consume_expr(&base);
+                self.consume_expr(base);
             }
 
             hir::ExprKind::Yield(ref value, _) => {
-                self.consume_expr(&value);
+                self.consume_expr(value);
             }
         }
     }
@@ -560,24 +372,12 @@ impl<'a, 'tcx> ExprUseVisitor<'a, 'tcx> {
             ty::Error => { }
             _ => {
                 if let Some(def_id) = self.mc.tables.type_dependent_def_id(call.hir_id) {
-                    let call_scope = region::Scope {
-                        id: call.hir_id.local_id,
-                        data: region::ScopeData::Node
-                    };
                     match OverloadedCallType::from_method_id(self.tcx(), def_id) {
                         FnMutOverloadedCall => {
-                            let call_scope_r = self.tcx().mk_region(ty::ReScope(call_scope));
-                            self.borrow_expr(callee,
-                                            call_scope_r,
-                                            ty::MutBorrow,
-                                            ClosureInvocation);
+                            self.borrow_expr(callee, ty::MutBorrow);
                         }
                         FnOverloadedCall => {
-                            let call_scope_r = self.tcx().mk_region(ty::ReScope(call_scope));
-                            self.borrow_expr(callee,
-                                            call_scope_r,
-                                            ty::ImmBorrow,
-                                            ClosureInvocation);
+                            self.borrow_expr(callee, ty::ImmBorrow);
                         }
                         FnOnceOverloadedCall => self.consume_expr(callee),
                     }
@@ -608,22 +408,14 @@ impl<'a, 'tcx> ExprUseVisitor<'a, 'tcx> {
     }
 
     fn walk_local(&mut self, local: &hir::Local) {
-        match local.init {
-            None => {
-                local.pat.each_binding(|_, hir_id, span, _| {
-                    self.delegate.decl_without_init(hir_id, span);
-                })
-            }
-
-            Some(ref expr) => {
-                // Variable declarations with
-                // initializers are considered
-                // "assigns", which is handled by
-                // `walk_pat`:
-                self.walk_expr(&expr);
-                let init_cmt = Rc::new(return_if_err!(self.mc.cat_expr(&expr)));
-                self.walk_irrefutable_pat(init_cmt, &local.pat);
-            }
+        if let Some(ref expr) = local.init {
+            // Variable declarations with
+            // initializers are considered
+            // "assigns", which is handled by
+            // `walk_pat`:
+            self.walk_expr(&expr);
+            let init_cmt = Rc::new(return_if_err!(self.mc.cat_expr(&expr)));
+            self.walk_irrefutable_pat(init_cmt, &local.pat);
         }
     }
 
@@ -673,7 +465,7 @@ impl<'a, 'tcx> ExprUseVisitor<'a, 'tcx> {
                             with_field.ident,
                             with_field.ty(self.tcx(), substs)
                         );
-                        self.delegate_consume(with_expr.hir_id, with_expr.span, &cmt_field);
+                        self.delegate_consume(&cmt_field);
                     }
                 }
             }
@@ -708,7 +500,7 @@ impl<'a, 'tcx> ExprUseVisitor<'a, 'tcx> {
                 adjustment::Adjust::Pointer(_)  => {
                     // Creating a closure/fn-pointer or unsizing consumes
                     // the input and stores it into the resulting rvalue.
-                    self.delegate_consume(expr.hir_id, expr.span, &cmt);
+                    self.delegate_consume(&cmt);
                 }
 
                 adjustment::Adjust::Deref(None) => {}
@@ -720,7 +512,7 @@ impl<'a, 'tcx> ExprUseVisitor<'a, 'tcx> {
                 // this is an autoref of `x`.
                 adjustment::Adjust::Deref(Some(ref deref)) => {
                     let bk = ty::BorrowKind::from_mutbl(deref.mutbl);
-                    self.delegate.borrow(expr.hir_id, expr.span, &cmt, deref.region, bk, AutoRef);
+                    self.delegate.borrow(&cmt, bk);
                 }
 
                 adjustment::Adjust::Borrow(ref autoref) => {
@@ -744,13 +536,8 @@ impl<'a, 'tcx> ExprUseVisitor<'a, 'tcx> {
                autoref);
 
         match *autoref {
-            adjustment::AutoBorrow::Ref(r, m) => {
-                self.delegate.borrow(expr.hir_id,
-                                     expr.span,
-                                     cmt_base,
-                                     r,
-                                     ty::BorrowKind::from_mutbl(m.into()),
-                                     AutoRef);
+            adjustment::AutoBorrow::Ref(_, m) => {
+                self.delegate.borrow(cmt_base, ty::BorrowKind::from_mutbl(m.into()));
             }
 
             adjustment::AutoBorrow::RawPtr(m) => {
@@ -758,33 +545,14 @@ impl<'a, 'tcx> ExprUseVisitor<'a, 'tcx> {
                        expr.hir_id,
                        cmt_base);
 
-                // Converting from a &T to *T (or &mut T to *mut T) is
-                // treated as borrowing it for the enclosing temporary
-                // scope.
-                let r = self.tcx().mk_region(ty::ReScope(
-                    region::Scope {
-                        id: expr.hir_id.local_id,
-                        data: region::ScopeData::Node
-                    }));
-
-                self.delegate.borrow(expr.hir_id,
-                                     expr.span,
-                                     cmt_base,
-                                     r,
-                                     ty::BorrowKind::from_mutbl(m),
-                                     AutoUnsafe);
+
+                self.delegate.borrow(cmt_base, ty::BorrowKind::from_mutbl(m));
             }
         }
     }
 
-    fn arm_move_mode(&mut self, discr_cmt: mc::cmt<'tcx>, arm: &hir::Arm) -> TrackMatchMode {
-        let mut mode = Unknown;
-        self.determine_pat_move_mode(discr_cmt.clone(), &arm.pat, &mut mode);
-        mode
-    }
-
-    fn walk_arm(&mut self, discr_cmt: mc::cmt<'tcx>, arm: &hir::Arm, mode: MatchMode) {
-        self.walk_pat(discr_cmt.clone(), &arm.pat, mode);
+    fn walk_arm(&mut self, discr_cmt: mc::cmt<'tcx>, arm: &hir::Arm) {
+        self.walk_pat(discr_cmt.clone(), &arm.pat);
 
         if let Some(hir::Guard::If(ref e)) = arm.guard {
             self.consume_expr(e)
@@ -796,44 +564,12 @@ impl<'a, 'tcx> ExprUseVisitor<'a, 'tcx> {
     /// Walks a pat that occurs in isolation (i.e., top-level of fn argument or
     /// let binding, and *not* a match arm or nested pat.)
     fn walk_irrefutable_pat(&mut self, cmt_discr: mc::cmt<'tcx>, pat: &hir::Pat) {
-        let mut mode = Unknown;
-        self.determine_pat_move_mode(cmt_discr.clone(), pat, &mut mode);
-        let mode = mode.match_mode();
-        self.walk_pat(cmt_discr, pat, mode);
+        self.walk_pat(cmt_discr, pat);
     }
 
-    /// Identifies any bindings within `pat` and accumulates within
-    /// `mode` whether the overall pattern/match structure is a move,
-    /// copy, or borrow.
-    fn determine_pat_move_mode(&mut self,
-                               cmt_discr: mc::cmt<'tcx>,
-                               pat: &hir::Pat,
-                               mode: &mut TrackMatchMode) {
-        debug!("determine_pat_move_mode cmt_discr={:?} pat={:?}", cmt_discr, pat);
-
-        return_if_err!(self.mc.cat_pattern(cmt_discr, pat, |cmt_pat, pat| {
-            if let PatKind::Binding(..) = pat.kind {
-                let bm = *self.mc.tables.pat_binding_modes()
-                                        .get(pat.hir_id)
-                                        .expect("missing binding mode");
-                match bm {
-                    ty::BindByReference(..) =>
-                        mode.lub(BorrowingMatch),
-                    ty::BindByValue(..) => {
-                        match copy_or_move(&self.mc, self.param_env, &cmt_pat, PatBindingMove) {
-                            Copy => mode.lub(CopyingMatch),
-                            Move(..) => mode.lub(MovingMatch),
-                        }
-                    }
-                }
-            }
-        }));
-    }
 
-    /// The core driver for walking a pattern; `match_mode` must be
-    /// established up front, e.g., via `determine_pat_move_mode` (see
-    /// also `walk_irrefutable_pat` for patterns that stand alone).
-    fn walk_pat(&mut self, cmt_discr: mc::cmt<'tcx>, pat: &hir::Pat, match_mode: MatchMode) {
+    /// The core driver for walking a pattern
+    fn walk_pat(&mut self, cmt_discr: mc::cmt<'tcx>, pat: &hir::Pat) {
         debug!("walk_pat(cmt_discr={:?}, pat={:?})", cmt_discr, pat);
 
         let tcx = self.tcx();
@@ -841,10 +577,9 @@ impl<'a, 'tcx> ExprUseVisitor<'a, 'tcx> {
         return_if_err!(mc.cat_pattern(cmt_discr.clone(), pat, |cmt_pat, pat| {
             if let PatKind::Binding(_, canonical_id, ..) = pat.kind {
                 debug!(
-                    "walk_pat: binding cmt_pat={:?} pat={:?} match_mode={:?}",
+                    "walk_pat: binding cmt_pat={:?} pat={:?}",
                     cmt_pat,
                     pat,
-                    match_mode,
                 );
                 if let Some(&bm) = mc.tables.pat_binding_modes().get(pat.hir_id) {
                     debug!("walk_pat: pat.hir_id={:?} bm={:?}", pat.hir_id, bm);
@@ -857,21 +592,19 @@ impl<'a, 'tcx> ExprUseVisitor<'a, 'tcx> {
                     // binding being produced.
                     let def = Res::Local(canonical_id);
                     if let Ok(ref binding_cmt) = mc.cat_res(pat.hir_id, pat.span, pat_ty, def) {
-                        delegate.mutate(pat.hir_id, pat.span, binding_cmt, MutateMode::Init);
+                        delegate.mutate(binding_cmt);
                     }
 
                     // It is also a borrow or copy/move of the value being matched.
                     match bm {
                         ty::BindByReference(m) => {
-                            if let ty::Ref(r, _, _) = pat_ty.kind {
-                                let bk = ty::BorrowKind::from_mutbl(m);
-                                delegate.borrow(pat.hir_id, pat.span, &cmt_pat, r, bk, RefBinding);
-                            }
+                            let bk = ty::BorrowKind::from_mutbl(m);
+                            delegate.borrow(&cmt_pat, bk);
                         }
                         ty::BindByValue(..) => {
-                            let mode = copy_or_move(mc, param_env, &cmt_pat, PatBindingMove);
+                            let mode = copy_or_move(mc, param_env, &cmt_pat);
                             debug!("walk_pat binding consuming pat");
-                            delegate.consume_pat(pat, &cmt_pat, mode);
+                            delegate.consume(&cmt_pat, mode);
                         }
                     }
                 } else {
@@ -879,45 +612,6 @@ impl<'a, 'tcx> ExprUseVisitor<'a, 'tcx> {
                 }
             }
         }));
-
-        // Do a second pass over the pattern, calling `matched_pat` on
-        // the interior nodes (enum variants and structs), as opposed
-        // to the above loop's visit of than the bindings that form
-        // the leaves of the pattern tree structure.
-        return_if_err!(mc.cat_pattern(cmt_discr, pat, |cmt_pat, pat| {
-            let qpath = match pat.kind {
-                PatKind::Path(ref qpath) |
-                PatKind::TupleStruct(ref qpath, ..) |
-                PatKind::Struct(ref qpath, ..) => qpath,
-                _ => return
-            };
-            let res = mc.tables.qpath_res(qpath, pat.hir_id);
-            match res {
-                Res::Def(DefKind::Ctor(CtorOf::Variant, ..), variant_ctor_did) => {
-                    let variant_did = mc.tcx.parent(variant_ctor_did).unwrap();
-                    let downcast_cmt = mc.cat_downcast_if_needed(pat, cmt_pat, variant_did);
-
-                    debug!("variantctor downcast_cmt={:?} pat={:?}", downcast_cmt, pat);
-                    delegate.matched_pat(pat, &downcast_cmt, match_mode);
-                }
-                Res::Def(DefKind::Variant, variant_did) => {
-                    let downcast_cmt = mc.cat_downcast_if_needed(pat, cmt_pat, variant_did);
-
-                    debug!("variant downcast_cmt={:?} pat={:?}", downcast_cmt, pat);
-                    delegate.matched_pat(pat, &downcast_cmt, match_mode);
-                }
-                Res::Def(DefKind::Struct, _)
-                | Res::Def(DefKind::Ctor(..), _)
-                | Res::Def(DefKind::Union, _)
-                | Res::Def(DefKind::TyAlias, _)
-                | Res::Def(DefKind::AssocTy, _)
-                | Res::SelfTy(..) => {
-                    debug!("struct cmt_pat={:?} pat={:?}", cmt_pat, pat);
-                    delegate.matched_pat(pat, &cmt_pat, match_mode);
-                }
-                _ => {}
-            }
-        }));
     }
 
     fn walk_captures(&mut self, closure_expr: &hir::Expr, fn_decl_span: Span) {
@@ -925,7 +619,7 @@ impl<'a, 'tcx> ExprUseVisitor<'a, 'tcx> {
 
         let closure_def_id = self.tcx().hir().local_def_id(closure_expr.hir_id);
         if let Some(upvars) = self.tcx().upvars(closure_def_id) {
-            for (&var_id, upvar) in upvars.iter() {
+            for &var_id in upvars.keys() {
                 let upvar_id = ty::UpvarId {
                     var_path: ty::UpvarPath { hir_id: var_id },
                     closure_expr_id: closure_def_id.to_local(),
@@ -936,19 +630,11 @@ impl<'a, 'tcx> ExprUseVisitor<'a, 'tcx> {
                                                                    var_id));
                 match upvar_capture {
                     ty::UpvarCapture::ByValue => {
-                        let mode = copy_or_move(&self.mc,
-                                                self.param_env,
-                                                &cmt_var,
-                                                CaptureMove);
-                        self.delegate.consume(closure_expr.hir_id, upvar.span, &cmt_var, mode);
+                        let mode = copy_or_move(&self.mc, self.param_env, &cmt_var);
+                        self.delegate.consume(&cmt_var, mode);
                     }
                     ty::UpvarCapture::ByRef(upvar_borrow) => {
-                        self.delegate.borrow(closure_expr.hir_id,
-                                             fn_decl_span,
-                                             &cmt_var,
-                                             upvar_borrow.region,
-                                             upvar_borrow.kind,
-                                             ClosureCapture(upvar.span));
+                        self.delegate.borrow(&cmt_var, upvar_borrow.kind);
                     }
                 }
             }
@@ -971,10 +657,9 @@ fn copy_or_move<'a, 'tcx>(
     mc: &mc::MemCategorizationContext<'a, 'tcx>,
     param_env: ty::ParamEnv<'tcx>,
     cmt: &mc::cmt_<'tcx>,
-    move_reason: MoveReason,
 ) -> ConsumeMode {
     if !mc.type_is_copy_modulo_regions(param_env, cmt.ty, cmt.span) {
-        Move(move_reason)
+        Move
     } else {
         Copy
     }
diff --git a/src/librustc/middle/mem_categorization.rs b/src/librustc/middle/mem_categorization.rs
index 355bf97e6ed..8f79b8aa295 100644
--- a/src/librustc/middle/mem_categorization.rs
+++ b/src/librustc/middle/mem_categorization.rs
@@ -79,12 +79,11 @@ use std::fmt;
 use std::hash::{Hash, Hasher};
 use rustc_data_structures::fx::FxIndexMap;
 use std::rc::Rc;
-use crate::util::nodemap::ItemLocalSet;
 
 #[derive(Clone, Debug, PartialEq)]
 pub enum Categorization<'tcx> {
-    Rvalue(ty::Region<'tcx>),            // temporary val, argument is its scope
-    ThreadLocal(ty::Region<'tcx>),       // value that cannot move, but still restricted in scope
+    Rvalue,                              // temporary val
+    ThreadLocal,                         // value that cannot move, but still restricted in scope
     StaticItem,
     Upvar(Upvar),                        // upvar referenced by closure env
     Local(hir::HirId),                   // local variable
@@ -219,7 +218,6 @@ pub struct MemCategorizationContext<'a, 'tcx> {
     pub upvars: Option<&'tcx FxIndexMap<hir::HirId, hir::Upvar>>,
     pub region_scope_tree: &'a region::ScopeTree,
     pub tables: &'a ty::TypeckTables<'tcx>,
-    rvalue_promotable_map: Option<&'tcx ItemLocalSet>,
     infcx: Option<&'a InferCtxt<'a, 'tcx>>,
 }
 
@@ -335,7 +333,6 @@ impl<'a, 'tcx> MemCategorizationContext<'a, 'tcx> {
         body_owner: DefId,
         region_scope_tree: &'a region::ScopeTree,
         tables: &'a ty::TypeckTables<'tcx>,
-        rvalue_promotable_map: Option<&'tcx ItemLocalSet>,
     ) -> MemCategorizationContext<'a, 'tcx> {
         MemCategorizationContext {
             tcx,
@@ -343,7 +340,6 @@ impl<'a, 'tcx> MemCategorizationContext<'a, 'tcx> {
             upvars: tcx.upvars(body_owner),
             region_scope_tree,
             tables,
-            rvalue_promotable_map,
             infcx: None,
             param_env,
         }
@@ -369,19 +365,12 @@ impl<'a, 'tcx> MemCategorizationContext<'a, 'tcx> {
     ) -> MemCategorizationContext<'a, 'tcx> {
         let tcx = infcx.tcx;
 
-        // Subtle: we can't do rvalue promotion analysis until the
-        // typeck phase is complete, which means that you can't trust
-        // the rvalue lifetimes that result, but that's ok, since we
-        // don't need to know those during type inference.
-        let rvalue_promotable_map = None;
-
         MemCategorizationContext {
             tcx,
             body_owner,
             upvars: tcx.upvars(body_owner),
             region_scope_tree,
             tables,
-            rvalue_promotable_map,
             infcx: Some(infcx),
             param_env,
         }
@@ -664,8 +653,7 @@ impl<'a, 'tcx> MemCategorizationContext<'a, 'tcx> {
                     .any(|attr| attr.check_name(sym::thread_local));
 
                 let cat = if is_thread_local {
-                    let re = self.temporary_scope(hir_id.local_id);
-                    Categorization::ThreadLocal(re)
+                    Categorization::ThreadLocal
                 } else {
                     Categorization::StaticItem
                 };
@@ -878,16 +866,6 @@ impl<'a, 'tcx> MemCategorizationContext<'a, 'tcx> {
         ret
     }
 
-    /// Returns the lifetime of a temporary created by expr with id `id`.
-    /// This could be `'static` if `id` is part of a constant expression.
-    pub fn temporary_scope(&self, id: hir::ItemLocalId) -> ty::Region<'tcx> {
-        let scope = self.region_scope_tree.temporary_scope(id);
-        self.tcx.mk_region(match scope {
-            Some(scope) => ty::ReScope(scope),
-            None => ty::ReStatic
-        })
-    }
-
     pub fn cat_rvalue_node(&self,
                            hir_id: hir::HirId,
                            span: Span,
@@ -896,28 +874,7 @@ impl<'a, 'tcx> MemCategorizationContext<'a, 'tcx> {
         debug!("cat_rvalue_node(id={:?}, span={:?}, expr_ty={:?})",
                hir_id, span, expr_ty);
 
-        let promotable = self.rvalue_promotable_map.as_ref().map(|m| m.contains(&hir_id.local_id))
-                                                            .unwrap_or(false);
-
-        debug!("cat_rvalue_node: promotable = {:?}", promotable);
-
-        // Always promote `[T; 0]` (even when e.g., borrowed mutably).
-        let promotable = match expr_ty.kind {
-            ty::Array(_, len) if len.try_eval_usize(self.tcx, self.param_env) == Some(0) => true,
-            _ => promotable,
-        };
-
-        debug!("cat_rvalue_node: promotable = {:?} (2)", promotable);
-
-        // Compute maximum lifetime of this rvalue. This is 'static if
-        // we can promote to a constant, otherwise equal to enclosing temp
-        // lifetime.
-        let re = if promotable {
-            self.tcx.lifetimes.re_static
-        } else {
-            self.temporary_scope(hir_id.local_id)
-        };
-        let ret = self.cat_rvalue(hir_id, span, re, expr_ty);
+        let ret = self.cat_rvalue(hir_id, span, expr_ty);
         debug!("cat_rvalue_node ret {:?}", ret);
         ret
     }
@@ -925,12 +882,11 @@ impl<'a, 'tcx> MemCategorizationContext<'a, 'tcx> {
     pub fn cat_rvalue(&self,
                       cmt_hir_id: hir::HirId,
                       span: Span,
-                      temp_scope: ty::Region<'tcx>,
                       expr_ty: Ty<'tcx>) -> cmt_<'tcx> {
         let ret = cmt_ {
             hir_id: cmt_hir_id,
             span:span,
-            cat:Categorization::Rvalue(temp_scope),
+            cat:Categorization::Rvalue,
             mutbl:McDeclared,
             ty:expr_ty,
             note: NoteNone
@@ -1378,9 +1334,9 @@ impl<'tcx> cmt_<'tcx> {
         //! determines how long the value in `self` remains live.
 
         match self.cat {
-            Categorization::Rvalue(..) |
+            Categorization::Rvalue |
             Categorization::StaticItem |
-            Categorization::ThreadLocal(..) |
+            Categorization::ThreadLocal |
             Categorization::Local(..) |
             Categorization::Deref(_, UnsafePtr(..)) |
             Categorization::Deref(_, BorrowedPtr(..)) |
@@ -1411,8 +1367,8 @@ impl<'tcx> cmt_<'tcx> {
                 b.freely_aliasable()
             }
 
-            Categorization::Rvalue(..) |
-            Categorization::ThreadLocal(..) |
+            Categorization::Rvalue |
+            Categorization::ThreadLocal |
             Categorization::Local(..) |
             Categorization::Upvar(..) |
             Categorization::Deref(_, UnsafePtr(..)) => { // yes, it's aliasable, but...
@@ -1459,10 +1415,10 @@ impl<'tcx> cmt_<'tcx> {
             Categorization::StaticItem => {
                 "static item".into()
             }
-            Categorization::ThreadLocal(..) => {
+            Categorization::ThreadLocal => {
                 "thread-local static item".into()
             }
-            Categorization::Rvalue(..) => {
+            Categorization::Rvalue => {
                 "non-place".into()
             }
             Categorization::Local(vid) => {
diff --git a/src/librustc/query/mod.rs b/src/librustc/query/mod.rs
index e463810b7af..c95652f274e 100644
--- a/src/librustc/query/mod.rs
+++ b/src/librustc/query/mod.rs
@@ -94,6 +94,7 @@ rustc_queries! {
         /// of the MIR qualify_consts pass. The actual meaning of
         /// the value isn't known except to the pass itself.
         query mir_const_qualif(key: DefId) -> (u8, &'tcx BitSet<mir::Local>) {
+            desc { |tcx| "const checking `{}`", tcx.def_path_str(key) }
             cache_on_disk_if { key.is_local() }
         }
 
@@ -530,19 +531,6 @@ rustc_queries! {
 
     TypeChecking {
         query trait_of_item(_: DefId) -> Option<DefId> {}
-        query const_is_rvalue_promotable_to_static(key: DefId) -> bool {
-            desc { |tcx|
-                "const checking if rvalue is promotable to static `{}`",
-                tcx.def_path_str(key)
-            }
-            cache_on_disk_if { true }
-        }
-        query rvalue_promotable_map(key: DefId) -> &'tcx ItemLocalSet {
-            desc { |tcx|
-                "checking which parts of `{}` are promotable to static",
-                tcx.def_path_str(key)
-            }
-        }
     }
 
     Codegen {
diff --git a/src/librustc/ty/query/mod.rs b/src/librustc/ty/query/mod.rs
index 863721a5b4b..4279ca8c3da 100644
--- a/src/librustc/ty/query/mod.rs
+++ b/src/librustc/ty/query/mod.rs
@@ -37,7 +37,7 @@ use crate::ty::{self, CrateInherentImpls, ParamEnvAnd, Ty, TyCtxt, AdtSizedConst
 use crate::ty::steal::Steal;
 use crate::ty::util::NeedsDrop;
 use crate::ty::subst::SubstsRef;
-use crate::util::nodemap::{DefIdSet, DefIdMap, ItemLocalSet};
+use crate::util::nodemap::{DefIdSet, DefIdMap};
 use crate::util::common::ErrorReported;
 use crate::util::profiling::ProfileCategory::*;
 
diff --git a/src/librustc_interface/passes.rs b/src/librustc_interface/passes.rs
index 0055e0a8b2e..bf5e86017fc 100644
--- a/src/librustc_interface/passes.rs
+++ b/src/librustc_interface/passes.rs
@@ -917,9 +917,8 @@ fn analysis(tcx: TyCtxt<'_>, cnum: CrateNum) -> Result<()> {
 
     time(sess, "misc checking 2", || {
         parallel!({
-            time(sess, "rvalue promotion + match checking", || {
+            time(sess, "match checking", || {
                 tcx.par_body_owners(|def_id| {
-                    tcx.ensure().const_is_rvalue_promotable_to_static(def_id);
                     tcx.ensure().check_match(def_id);
                 });
             });
diff --git a/src/librustc_metadata/cstore_impl.rs b/src/librustc_metadata/cstore_impl.rs
index edb6f594fdd..0f80540b11e 100644
--- a/src/librustc_metadata/cstore_impl.rs
+++ b/src/librustc_metadata/cstore_impl.rs
@@ -154,9 +154,6 @@ provide! { <'tcx> tcx, def_id, other, cdata,
     rendered_const => { cdata.get_rendered_const(def_id.index) }
     impl_parent => { cdata.get_parent_impl(def_id.index) }
     trait_of_item => { cdata.get_trait_of_item(def_id.index) }
-    const_is_rvalue_promotable_to_static => {
-        cdata.const_is_rvalue_promotable_to_static(def_id.index)
-    }
     is_mir_available => { cdata.is_item_mir_available(def_id.index) }
 
     dylib_dependency_formats => { cdata.get_dylib_dependency_formats(tcx) }
diff --git a/src/librustc_metadata/decoder.rs b/src/librustc_metadata/decoder.rs
index 9fcc3101545..da0c7493b5c 100644
--- a/src/librustc_metadata/decoder.rs
+++ b/src/librustc_metadata/decoder.rs
@@ -915,14 +915,6 @@ impl<'a, 'tcx> CrateMetadata {
         }
     }
 
-    pub fn const_is_rvalue_promotable_to_static(&self, id: DefIndex) -> bool {
-        match self.entry(id).kind {
-            EntryKind::AssocConst(_, data, _) |
-            EntryKind::Const(data, _) => data.ast_promotable,
-            _ => bug!(),
-        }
-    }
-
     pub fn is_item_mir_available(&self, id: DefIndex) -> bool {
         !self.is_proc_macro(id) &&
         self.maybe_entry(id).and_then(|item| item.decode(self).mir).is_some()
diff --git a/src/librustc_metadata/encoder.rs b/src/librustc_metadata/encoder.rs
index 49577b56b14..bbfbba2e0d8 100644
--- a/src/librustc_metadata/encoder.rs
+++ b/src/librustc_metadata/encoder.rs
@@ -861,18 +861,11 @@ impl EncodeContext<'tcx> {
 
         let kind = match trait_item.kind {
             ty::AssocKind::Const => {
-                let const_qualif =
-                    if let hir::TraitItemKind::Const(_, Some(body)) = ast_item.kind {
-                        self.const_qualif(0, body)
-                    } else {
-                        ConstQualif { mir: 0, ast_promotable: false }
-                    };
-
                 let rendered =
                     hir::print::to_string(self.tcx.hir(), |s| s.print_trait_item(ast_item));
                 let rendered_const = self.lazy(RenderedConst(rendered));
 
-                EntryKind::AssocConst(container, const_qualif, rendered_const)
+                EntryKind::AssocConst(container, ConstQualif { mir: 0 }, rendered_const)
             }
             ty::AssocKind::Method => {
                 let fn_data = if let hir::TraitItemKind::Method(method_sig, m) = &ast_item.kind {
@@ -946,13 +939,6 @@ impl EncodeContext<'tcx> {
         !self.tcx.sess.opts.output_types.should_codegen()
     }
 
-    fn const_qualif(&self, mir: u8, body_id: hir::BodyId) -> ConstQualif {
-        let body_owner_def_id = self.tcx.hir().body_owner_def_id(body_id);
-        let ast_promotable = self.tcx.const_is_rvalue_promotable_to_static(body_owner_def_id);
-
-        ConstQualif { mir, ast_promotable }
-    }
-
     fn encode_info_for_impl_item(&mut self, def_id: DefId) -> Entry<'tcx> {
         debug!("EncodeContext::encode_info_for_impl_item({:?})", def_id);
         let tcx = self.tcx;
@@ -974,7 +960,7 @@ impl EncodeContext<'tcx> {
                     let mir = self.tcx.at(ast_item.span).mir_const_qualif(def_id).0;
 
                     EntryKind::AssocConst(container,
-                        self.const_qualif(mir, body_id),
+                        ConstQualif { mir },
                         self.encode_rendered_const_for_body(body_id))
                 } else {
                     bug!()
@@ -1123,7 +1109,7 @@ impl EncodeContext<'tcx> {
             hir::ItemKind::Const(_, body_id) => {
                 let mir = tcx.at(item.span).mir_const_qualif(def_id).0;
                 EntryKind::Const(
-                    self.const_qualif(mir, body_id),
+                    ConstQualif { mir },
                     self.encode_rendered_const_for_body(body_id)
                 )
             }
@@ -1475,7 +1461,7 @@ impl EncodeContext<'tcx> {
         let mir = tcx.mir_const_qualif(def_id).0;
 
         Entry {
-            kind: EntryKind::Const(self.const_qualif(mir, body_id), const_data),
+            kind: EntryKind::Const(ConstQualif { mir }, const_data),
             visibility: self.lazy(ty::Visibility::Public),
             span: self.lazy(tcx.def_span(def_id)),
             attributes: Lazy::empty(),
diff --git a/src/librustc_metadata/schema.rs b/src/librustc_metadata/schema.rs
index 2069adea021..4fe9c466cb6 100644
--- a/src/librustc_metadata/schema.rs
+++ b/src/librustc_metadata/schema.rs
@@ -274,7 +274,6 @@ pub enum EntryKind<'tcx> {
 #[derive(Clone, Copy, RustcEncodable, RustcDecodable)]
 pub struct ConstQualif {
     pub mir: u8,
-    pub ast_promotable: bool,
 }
 
 /// Contains a constant which has been rendered to a String.
diff --git a/src/librustc_passes/lib.rs b/src/librustc_passes/lib.rs
index 4e29706714f..6c7958fb365 100644
--- a/src/librustc_passes/lib.rs
+++ b/src/librustc_passes/lib.rs
@@ -19,12 +19,10 @@ use rustc::ty::query::Providers;
 pub mod error_codes;
 
 pub mod ast_validation;
-pub mod rvalue_promotion;
 pub mod hir_stats;
 pub mod layout_test;
 pub mod loops;
 
 pub fn provide(providers: &mut Providers<'_>) {
-    rvalue_promotion::provide(providers);
     loops::provide(providers);
 }
diff --git a/src/librustc_passes/rvalue_promotion.rs b/src/librustc_passes/rvalue_promotion.rs
deleted file mode 100644
index a93ca7847d6..00000000000
--- a/src/librustc_passes/rvalue_promotion.rs
+++ /dev/null
@@ -1,658 +0,0 @@
-// Verifies that the types and values of const and static items
-// are safe. The rules enforced by this module are:
-//
-// - For each *mutable* static item, it checks that its **type**:
-//     - doesn't have a destructor
-//     - doesn't own a box
-//
-// - For each *immutable* static item, it checks that its **value**:
-//       - doesn't own a box
-//       - doesn't contain a struct literal or a call to an enum variant / struct constructor where
-//           - the type of the struct/enum has a dtor
-//
-// Rules Enforced Elsewhere:
-// - It's not possible to take the address of a static item with unsafe interior. This is enforced
-// by borrowck::gather_loans
-
-use rustc::ty::cast::CastTy;
-use rustc::hir::def::{Res, DefKind, CtorKind};
-use rustc::hir::def_id::DefId;
-use rustc::middle::expr_use_visitor as euv;
-use rustc::middle::mem_categorization as mc;
-use rustc::middle::mem_categorization::Categorization;
-use rustc::ty::{self, Ty, TyCtxt};
-use rustc::ty::query::Providers;
-use rustc::ty::subst::{InternalSubsts, SubstsRef};
-use rustc::util::nodemap::{ItemLocalSet, HirIdSet};
-use rustc::hir;
-use syntax::symbol::sym;
-use syntax_pos::{Span, DUMMY_SP};
-use log::debug;
-use Promotability::*;
-use std::ops::{BitAnd, BitAndAssign, BitOr};
-
-pub fn provide(providers: &mut Providers<'_>) {
-    *providers = Providers {
-        rvalue_promotable_map,
-        const_is_rvalue_promotable_to_static,
-        ..*providers
-    };
-}
-
-fn const_is_rvalue_promotable_to_static(tcx: TyCtxt<'_>, def_id: DefId) -> bool {
-    assert!(def_id.is_local());
-
-    let hir_id = tcx.hir().as_local_hir_id(def_id)
-        .expect("rvalue_promotable_map invoked with non-local def-id");
-    let body_id = tcx.hir().body_owned_by(hir_id);
-    tcx.rvalue_promotable_map(def_id).contains(&body_id.hir_id.local_id)
-}
-
-fn rvalue_promotable_map(tcx: TyCtxt<'_>, def_id: DefId) -> &ItemLocalSet {
-    let outer_def_id = tcx.closure_base_def_id(def_id);
-    if outer_def_id != def_id {
-        return tcx.rvalue_promotable_map(outer_def_id);
-    }
-
-    let mut visitor = CheckCrateVisitor {
-        tcx,
-        tables: &ty::TypeckTables::empty(None),
-        in_fn: false,
-        in_static: false,
-        mut_rvalue_borrows: Default::default(),
-        param_env: ty::ParamEnv::empty(),
-        identity_substs: InternalSubsts::empty(),
-        result: ItemLocalSet::default(),
-    };
-
-    // `def_id` should be a `Body` owner
-    let hir_id = tcx.hir().as_local_hir_id(def_id)
-        .expect("rvalue_promotable_map invoked with non-local def-id");
-    let body_id = tcx.hir().body_owned_by(hir_id);
-    let _ = visitor.check_nested_body(body_id);
-
-    tcx.arena.alloc(visitor.result)
-}
-
-struct CheckCrateVisitor<'a, 'tcx> {
-    tcx: TyCtxt<'tcx>,
-    in_fn: bool,
-    in_static: bool,
-    mut_rvalue_borrows: HirIdSet,
-    param_env: ty::ParamEnv<'tcx>,
-    identity_substs: SubstsRef<'tcx>,
-    tables: &'a ty::TypeckTables<'tcx>,
-    result: ItemLocalSet,
-}
-
-#[must_use]
-#[derive(Debug, Clone, Copy, PartialEq)]
-enum Promotability {
-    Promotable,
-    NotPromotable
-}
-
-impl BitAnd for Promotability {
-    type Output = Self;
-
-    fn bitand(self, rhs: Self) -> Self {
-        match (self, rhs) {
-            (Promotable, Promotable) => Promotable,
-            _ => NotPromotable,
-        }
-    }
-}
-
-impl BitAndAssign for Promotability {
-    fn bitand_assign(&mut self, rhs: Self) {
-        *self = *self & rhs
-    }
-}
-
-impl BitOr for Promotability {
-    type Output = Self;
-
-    fn bitor(self, rhs: Self) -> Self {
-        match (self, rhs) {
-            (NotPromotable, NotPromotable) => NotPromotable,
-            _ => Promotable,
-        }
-    }
-}
-
-impl<'a, 'tcx> CheckCrateVisitor<'a, 'tcx> {
-    // Returns true iff all the values of the type are promotable.
-    fn type_promotability(&mut self, ty: Ty<'tcx>) -> Promotability {
-        debug!("type_promotability({})", ty);
-
-        if ty.is_freeze(self.tcx, self.param_env, DUMMY_SP) &&
-            !ty.needs_drop(self.tcx, self.param_env) {
-            Promotable
-        } else {
-            NotPromotable
-        }
-    }
-
-    fn handle_const_fn_call(
-        &mut self,
-        def_id: DefId,
-    ) -> Promotability {
-        if self.tcx.is_promotable_const_fn(def_id) {
-            Promotable
-        } else {
-            NotPromotable
-        }
-    }
-
-    /// While the `ExprUseVisitor` walks, we will identify which
-    /// expressions are borrowed, and insert their IDs into this
-    /// table. Actually, we insert the "borrow-id", which is normally
-    /// the ID of the expression being borrowed: but in the case of
-    /// `ref mut` borrows, the `id` of the pattern is
-    /// inserted. Therefore, later we remove that entry from the table
-    /// and transfer it over to the value being matched. This will
-    /// then prevent said value from being promoted.
-    fn remove_mut_rvalue_borrow(&mut self, pat: &hir::Pat) -> bool {
-        let mut any_removed = false;
-        pat.walk(|p| {
-            any_removed |= self.mut_rvalue_borrows.remove(&p.hir_id);
-            true
-        });
-        any_removed
-    }
-}
-
-impl<'a, 'tcx> CheckCrateVisitor<'a, 'tcx> {
-    fn check_nested_body(&mut self, body_id: hir::BodyId) -> Promotability {
-        let item_id = self.tcx.hir().body_owner(body_id);
-        let item_def_id = self.tcx.hir().local_def_id(item_id);
-
-        let outer_in_fn = self.in_fn;
-        let outer_tables = self.tables;
-        let outer_param_env = self.param_env;
-        let outer_identity_substs = self.identity_substs;
-
-        self.in_fn = false;
-        self.in_static = false;
-
-        match self.tcx.hir().body_owner_kind(item_id) {
-            hir::BodyOwnerKind::Closure |
-            hir::BodyOwnerKind::Fn => self.in_fn = true,
-            hir::BodyOwnerKind::Static(_) => self.in_static = true,
-            _ => {}
-        };
-
-
-        self.tables = self.tcx.typeck_tables_of(item_def_id);
-        self.param_env = self.tcx.param_env(item_def_id);
-        self.identity_substs = InternalSubsts::identity_for_item(self.tcx, item_def_id);
-
-        let body = self.tcx.hir().body(body_id);
-
-        let tcx = self.tcx;
-        let param_env = self.param_env;
-        let region_scope_tree = self.tcx.region_scope_tree(item_def_id);
-        let tables = self.tables;
-        euv::ExprUseVisitor::new(
-            self,
-            tcx,
-            item_def_id,
-            param_env,
-            &region_scope_tree,
-            tables,
-            None,
-        ).consume_body(body);
-
-        let body_promotable = self.check_expr(&body.value);
-        self.in_fn = outer_in_fn;
-        self.tables = outer_tables;
-        self.param_env = outer_param_env;
-        self.identity_substs = outer_identity_substs;
-        body_promotable
-    }
-
-    fn check_stmt(&mut self, stmt: &'tcx hir::Stmt) -> Promotability {
-        match stmt.kind {
-            hir::StmtKind::Local(ref local) => {
-                if self.remove_mut_rvalue_borrow(&local.pat) {
-                    if let Some(init) = &local.init {
-                        self.mut_rvalue_borrows.insert(init.hir_id);
-                    }
-                }
-
-                if let Some(ref expr) = local.init {
-                    let _ = self.check_expr(&expr);
-                }
-                NotPromotable
-            }
-            // Item statements are allowed
-            hir::StmtKind::Item(..) => Promotable,
-            hir::StmtKind::Expr(ref box_expr) |
-            hir::StmtKind::Semi(ref box_expr) => {
-                let _ = self.check_expr(box_expr);
-                NotPromotable
-            }
-        }
-    }
-
-    fn check_expr(&mut self, ex: &'tcx hir::Expr) -> Promotability {
-        let node_ty = self.tables.node_type(ex.hir_id);
-        let mut outer = check_expr_kind(self, ex, node_ty);
-        outer &= check_adjustments(self, ex);
-
-        // Handle borrows on (or inside the autorefs of) this expression.
-        if self.mut_rvalue_borrows.remove(&ex.hir_id) {
-            outer = NotPromotable
-        }
-
-        if outer == Promotable {
-            self.result.insert(ex.hir_id.local_id);
-        }
-        outer
-    }
-
-    fn check_block(&mut self, block: &'tcx hir::Block) -> Promotability {
-        let mut iter_result = Promotable;
-        for index in block.stmts.iter() {
-            iter_result &= self.check_stmt(index);
-        }
-        match block.expr {
-            Some(ref box_expr) => iter_result & self.check_expr(&*box_expr),
-            None => iter_result,
-        }
-    }
-}
-
-/// This function is used to enforce the constraints on
-/// const/static items. It walks through the *value*
-/// of the item walking down the expression and evaluating
-/// every nested expression. If the expression is not part
-/// of a const/static item, it is qualified for promotion
-/// instead of producing errors.
-fn check_expr_kind<'a, 'tcx>(
-    v: &mut CheckCrateVisitor<'a, 'tcx>,
-    e: &'tcx hir::Expr, node_ty: Ty<'tcx>) -> Promotability {
-
-    let ty_result = match node_ty.kind {
-        ty::Adt(def, _) if def.has_dtor(v.tcx) => {
-            NotPromotable
-        }
-        _ => Promotable
-    };
-
-    let kind_result = match e.kind {
-        hir::ExprKind::Box(ref expr) => {
-            let _ = v.check_expr(&expr);
-            NotPromotable
-        }
-        hir::ExprKind::Unary(op, ref expr) => {
-            let expr_promotability = v.check_expr(expr);
-            if v.tables.is_method_call(e) || op == hir::UnDeref {
-                return NotPromotable;
-            }
-            expr_promotability
-        }
-        hir::ExprKind::Binary(op, ref lhs, ref rhs) => {
-            let lefty = v.check_expr(lhs);
-            let righty = v.check_expr(rhs);
-            if v.tables.is_method_call(e) {
-                return NotPromotable;
-            }
-            match v.tables.node_type(lhs.hir_id).kind {
-                ty::RawPtr(_) | ty::FnPtr(..) => {
-                    assert!(op.node == hir::BinOpKind::Eq || op.node == hir::BinOpKind::Ne ||
-                            op.node == hir::BinOpKind::Le || op.node == hir::BinOpKind::Lt ||
-                            op.node == hir::BinOpKind::Ge || op.node == hir::BinOpKind::Gt);
-
-                    NotPromotable
-                }
-                _ => lefty & righty
-            }
-        }
-        hir::ExprKind::Cast(ref from, _) => {
-            let expr_promotability = v.check_expr(from);
-            debug!("checking const cast(id={})", from.hir_id);
-            let cast_in = CastTy::from_ty(v.tables.expr_ty(from));
-            let cast_out = CastTy::from_ty(v.tables.expr_ty(e));
-            match (cast_in, cast_out) {
-                (Some(CastTy::FnPtr), Some(CastTy::Int(_))) |
-                (Some(CastTy::Ptr(_)), Some(CastTy::Int(_))) => NotPromotable,
-                (_, _) => expr_promotability
-            }
-        }
-        hir::ExprKind::Path(ref qpath) => {
-            let res = v.tables.qpath_res(qpath, e.hir_id);
-            match res {
-                Res::Def(DefKind::Ctor(..), _)
-                | Res::Def(DefKind::Fn, _)
-                | Res::Def(DefKind::Method, _)
-                | Res::SelfCtor(..) =>
-                    Promotable,
-
-                // References to a static that are themselves within a static
-                // are inherently promotable with the exception
-                //  of "#[thread_local]" statics, which may not
-                // outlive the current function
-                Res::Def(DefKind::Static, did) => {
-
-                    if v.in_static {
-                        for attr in &v.tcx.get_attrs(did)[..] {
-                            if attr.check_name(sym::thread_local) {
-                                debug!("reference to `Static(id={:?})` is unpromotable \
-                                        due to a `#[thread_local]` attribute", did);
-                                return NotPromotable;
-                            }
-                        }
-                        Promotable
-                    } else {
-                        debug!("reference to `Static(id={:?})` is unpromotable as it is not \
-                                referenced from a static", did);
-                        NotPromotable
-                    }
-                }
-
-                Res::Def(DefKind::Const, did) |
-                Res::Def(DefKind::AssocConst, did) => {
-                    let promotable = if v.tcx.trait_of_item(did).is_some() {
-                        // Don't peek inside trait associated constants.
-                        NotPromotable
-                    } else if v.tcx.at(e.span).const_is_rvalue_promotable_to_static(did) {
-                        Promotable
-                    } else {
-                        NotPromotable
-                    };
-                    // Just in case the type is more specific than the definition,
-                    // e.g., impl associated const with type parameters, check it.
-                    // Also, trait associated consts are relaxed by this.
-                    promotable | v.type_promotability(node_ty)
-                }
-                _ => NotPromotable
-            }
-        }
-        hir::ExprKind::Call(ref callee, ref hirvec) => {
-            let mut call_result = v.check_expr(callee);
-            for index in hirvec.iter() {
-                call_result &= v.check_expr(index);
-            }
-            let mut callee = &**callee;
-            loop {
-                callee = match callee.kind {
-                    hir::ExprKind::Block(ref block, _) => match block.expr {
-                        Some(ref tail) => &tail,
-                        None => break
-                    },
-                    _ => break
-                };
-            }
-            // The callee is an arbitrary expression, it doesn't necessarily have a definition.
-            let def = if let hir::ExprKind::Path(ref qpath) = callee.kind {
-                v.tables.qpath_res(qpath, callee.hir_id)
-            } else {
-                Res::Err
-            };
-            let def_result = match def {
-                Res::Def(DefKind::Ctor(_, CtorKind::Fn), _) |
-                Res::SelfCtor(..) => Promotable,
-                Res::Def(DefKind::Fn, did) => v.handle_const_fn_call(did),
-                Res::Def(DefKind::Method, did) => {
-                    match v.tcx.associated_item(did).container {
-                        ty::ImplContainer(_) => v.handle_const_fn_call(did),
-                        ty::TraitContainer(_) => NotPromotable,
-                    }
-                }
-                _ => NotPromotable,
-            };
-            def_result & call_result
-        }
-        hir::ExprKind::MethodCall(ref _pathsegment, ref _span, ref hirvec) => {
-            let mut method_call_result = Promotable;
-            for index in hirvec.iter() {
-                method_call_result &= v.check_expr(index);
-            }
-            if let Some(def_id) = v.tables.type_dependent_def_id(e.hir_id) {
-                match v.tcx.associated_item(def_id).container {
-                    ty::ImplContainer(_) => method_call_result & v.handle_const_fn_call(def_id),
-                    ty::TraitContainer(_) => NotPromotable,
-                }
-            } else {
-                v.tcx.sess.delay_span_bug(e.span, "no type-dependent def for method call");
-                NotPromotable
-            }
-        }
-        hir::ExprKind::Struct(ref _qpath, ref hirvec, ref option_expr) => {
-            let mut struct_result = Promotable;
-            for index in hirvec.iter() {
-                struct_result &= v.check_expr(&index.expr);
-            }
-            if let Some(ref expr) = *option_expr {
-                struct_result &= v.check_expr(&expr);
-            }
-            if let ty::Adt(adt, ..) = v.tables.expr_ty(e).kind {
-                // unsafe_cell_type doesn't necessarily exist with no_core
-                if Some(adt.did) == v.tcx.lang_items().unsafe_cell_type() {
-                    return NotPromotable;
-                }
-            }
-            struct_result
-        }
-
-        hir::ExprKind::Lit(_) |
-        hir::ExprKind::Err => Promotable,
-
-        hir::ExprKind::AddrOf(_, ref expr) |
-        hir::ExprKind::Repeat(ref expr, _) |
-        hir::ExprKind::Type(ref expr, _) |
-        hir::ExprKind::DropTemps(ref expr) => {
-            v.check_expr(&expr)
-        }
-
-        hir::ExprKind::Closure(_capture_clause, ref _box_fn_decl,
-                               body_id, _span, _option_generator_movability) => {
-            let nested_body_promotable = v.check_nested_body(body_id);
-            // Paths in constant contexts cannot refer to local variables,
-            // as there are none, and thus closures can't have upvars there.
-            let closure_def_id = v.tcx.hir().local_def_id(e.hir_id);
-            if !v.tcx.upvars(closure_def_id).map_or(true, |v| v.is_empty()) {
-                NotPromotable
-            } else {
-                nested_body_promotable
-            }
-        }
-
-        hir::ExprKind::Field(ref expr, _ident) => {
-            let expr_promotability = v.check_expr(&expr);
-            if let Some(def) = v.tables.expr_ty(expr).ty_adt_def() {
-                if def.is_union() {
-                    return NotPromotable;
-                }
-            }
-            expr_promotability
-        }
-
-        hir::ExprKind::Block(ref box_block, ref _option_label) => {
-            v.check_block(box_block)
-        }
-
-        hir::ExprKind::Index(ref lhs, ref rhs) => {
-            let lefty = v.check_expr(lhs);
-            let righty = v.check_expr(rhs);
-            if v.tables.is_method_call(e) {
-                return NotPromotable;
-            }
-            lefty & righty
-        }
-
-        hir::ExprKind::Array(ref hirvec) => {
-            let mut array_result = Promotable;
-            for index in hirvec.iter() {
-                array_result &= v.check_expr(index);
-            }
-            array_result
-        }
-
-        hir::ExprKind::Tup(ref hirvec) => {
-            let mut tup_result = Promotable;
-            for index in hirvec.iter() {
-                tup_result &= v.check_expr(index);
-            }
-            tup_result
-        }
-
-        // Conditional control flow (possible to implement).
-        hir::ExprKind::Match(ref expr, ref arms, ref _match_source) => {
-            // Compute the most demanding borrow from all the arms'
-            // patterns and set that on the discriminator.
-            if arms.iter().fold(false, |_, arm| v.remove_mut_rvalue_borrow(&arm.pat)) {
-                v.mut_rvalue_borrows.insert(expr.hir_id);
-            }
-
-            let _ = v.check_expr(expr);
-            for index in arms.iter() {
-                let _ = v.check_expr(&*index.body);
-                if let Some(hir::Guard::If(ref expr)) = index.guard {
-                    let _ = v.check_expr(&expr);
-                }
-            }
-            NotPromotable
-        }
-
-        hir::ExprKind::Loop(ref box_block, ref _option_label, ref _loop_source) => {
-            let _ = v.check_block(box_block);
-            NotPromotable
-        }
-
-        // More control flow (also not very meaningful).
-        hir::ExprKind::Break(_, ref option_expr) | hir::ExprKind::Ret(ref option_expr) => {
-            if let Some(ref expr) = *option_expr {
-                 let _ = v.check_expr(&expr);
-            }
-            NotPromotable
-        }
-
-        hir::ExprKind::Continue(_) => {
-            NotPromotable
-        }
-
-        // Generator expressions
-        hir::ExprKind::Yield(ref expr, _) => {
-            let _ = v.check_expr(&expr);
-            NotPromotable
-        }
-
-        // Expressions with side-effects.
-        hir::ExprKind::AssignOp(_, ref lhs, ref rhs) | hir::ExprKind::Assign(ref lhs, ref rhs) => {
-            let _ = v.check_expr(lhs);
-            let _ = v.check_expr(rhs);
-            NotPromotable
-        }
-
-        hir::ExprKind::InlineAsm(ref _inline_asm, ref hirvec_lhs, ref hirvec_rhs) => {
-            for index in hirvec_lhs.iter().chain(hirvec_rhs.iter()) {
-                let _ = v.check_expr(index);
-            }
-            NotPromotable
-        }
-    };
-    ty_result & kind_result
-}
-
-/// Checks the adjustments of an expression.
-fn check_adjustments<'a, 'tcx>(
-    v: &mut CheckCrateVisitor<'a, 'tcx>,
-    e: &hir::Expr) -> Promotability {
-    use rustc::ty::adjustment::*;
-
-    let mut adjustments = v.tables.expr_adjustments(e).iter().peekable();
-    while let Some(adjustment) = adjustments.next() {
-        match adjustment.kind {
-            Adjust::NeverToAny |
-            Adjust::Pointer(_) |
-            Adjust::Borrow(_) => {}
-
-            Adjust::Deref(_) => {
-                if let Some(next_adjustment) = adjustments.peek() {
-                    if let Adjust::Borrow(_) = next_adjustment.kind {
-                        continue;
-                    }
-                }
-                return NotPromotable;
-            }
-        }
-    }
-    Promotable
-}
-
-impl<'a, 'tcx> euv::Delegate<'tcx> for CheckCrateVisitor<'a, 'tcx> {
-    fn consume(&mut self,
-               _consume_id: hir::HirId,
-               _consume_span: Span,
-               _cmt: &mc::cmt_<'_>,
-               _mode: euv::ConsumeMode) {}
-
-    fn borrow(&mut self,
-              borrow_id: hir::HirId,
-              _borrow_span: Span,
-              cmt: &mc::cmt_<'tcx>,
-              _loan_region: ty::Region<'tcx>,
-              bk: ty::BorrowKind,
-              loan_cause: euv::LoanCause) {
-        debug!(
-            "borrow(borrow_id={:?}, cmt={:?}, bk={:?}, loan_cause={:?})",
-            borrow_id,
-            cmt,
-            bk,
-            loan_cause,
-        );
-
-        // Kind of hacky, but we allow Unsafe coercions in constants.
-        // These occur when we convert a &T or *T to a *U, as well as
-        // when making a thin pointer (e.g., `*T`) into a fat pointer
-        // (e.g., `*Trait`).
-        if let euv::LoanCause::AutoUnsafe = loan_cause {
-            return;
-        }
-
-        let mut cur = cmt;
-        loop {
-            match cur.cat {
-                Categorization::ThreadLocal(..) |
-                Categorization::Rvalue(..) => {
-                    if loan_cause == euv::MatchDiscriminant {
-                        // Ignore the dummy immutable borrow created by EUV.
-                        break;
-                    }
-                    if bk.to_mutbl_lossy() == hir::MutMutable {
-                        self.mut_rvalue_borrows.insert(borrow_id);
-                    }
-                    break;
-                }
-                Categorization::StaticItem => {
-                    break;
-                }
-                Categorization::Deref(ref cmt, _) |
-                Categorization::Downcast(ref cmt, _) |
-                Categorization::Interior(ref cmt, _) => {
-                    cur = cmt;
-                }
-
-                Categorization::Upvar(..) |
-                Categorization::Local(..) => break,
-            }
-        }
-    }
-
-    fn decl_without_init(&mut self, _id: hir::HirId, _span: Span) {}
-    fn mutate(&mut self,
-              _assignment_id: hir::HirId,
-              _assignment_span: Span,
-              _assignee_cmt: &mc::cmt_<'_>,
-              _mode: euv::MutateMode) {
-    }
-
-    fn matched_pat(&mut self, _: &hir::Pat, _: &mc::cmt_<'_>, _: euv::MatchMode) {}
-
-    fn consume_pat(&mut self,
-                   _consume_pat: &hir::Pat,
-                   _cmt: &mc::cmt_<'_>,
-                   _mode: euv::ConsumeMode) {}
-}
diff --git a/src/librustc_typeck/check/dropck.rs b/src/librustc_typeck/check/dropck.rs
index cb03af46f3d..d46ac4a39a3 100644
--- a/src/librustc_typeck/check/dropck.rs
+++ b/src/librustc_typeck/check/dropck.rs
@@ -3,10 +3,10 @@ use crate::check::regionck::RegionCtxt;
 use crate::hir;
 use crate::hir::def_id::DefId;
 use rustc::infer::outlives::env::OutlivesEnvironment;
-use rustc::infer::{self, InferOk, SuppressRegionErrors};
+use rustc::infer::{InferOk, SuppressRegionErrors};
 use rustc::middle::region;
 use rustc::traits::{ObligationCause, TraitEngine, TraitEngineExt};
-use rustc::ty::subst::{Subst, SubstsRef, GenericArgKind};
+use rustc::ty::subst::{Subst, SubstsRef};
 use rustc::ty::{self, Ty, TyCtxt};
 use crate::util::common::ErrorReported;
 
@@ -233,87 +233,21 @@ fn ensure_drop_predicates_are_implied_by_item_defn<'tcx>(
     result
 }
 
-/// This function confirms that the type
-/// expression `typ` conforms to the "Drop Check Rule" from the Sound
-/// Generic Drop RFC (#769).
-///
-/// ----
-///
-/// The simplified (*) Drop Check Rule is the following:
-///
-/// Let `v` be some value (either temporary or named) and 'a be some
-/// lifetime (scope). If the type of `v` owns data of type `D`, where
-///
-/// * (1.) `D` has a lifetime- or type-parametric Drop implementation,
-///        (where that `Drop` implementation does not opt-out of
-///         this check via the `may_dangle`
-///         attribute), and
-/// * (2.) the structure of `D` can reach a reference of type `&'a _`,
-///
-/// then 'a must strictly outlive the scope of v.
-///
-/// ----
-///
-/// This function is meant to by applied to the type for every
-/// expression in the program.
-///
-/// ----
-///
-/// (*) The qualifier "simplified" is attached to the above
-/// definition of the Drop Check Rule, because it is a simplification
-/// of the original Drop Check rule, which attempted to prove that
-/// some `Drop` implementations could not possibly access data even if
-/// it was technically reachable, due to parametricity.
-///
-/// However, (1.) parametricity on its own turned out to be a
-/// necessary but insufficient condition, and (2.)  future changes to
-/// the language are expected to make it impossible to ensure that a
-/// `Drop` implementation is actually parametric with respect to any
-/// particular type parameter. (In particular, impl specialization is
-/// expected to break the needed parametricity property beyond
-/// repair.)
-///
-/// Therefore, we have scaled back Drop-Check to a more conservative
-/// rule that does not attempt to deduce whether a `Drop`
-/// implementation could not possible access data of a given lifetime;
-/// instead Drop-Check now simply assumes that if a destructor has
-/// access (direct or indirect) to a lifetime parameter, then that
-/// lifetime must be forced to outlive that destructor's dynamic
-/// extent. We then provide the `may_dangle`
-/// attribute as a way for destructor implementations to opt-out of
-/// this conservative assumption (and thus assume the obligation of
-/// ensuring that they do not access data nor invoke methods of
-/// values that have been previously dropped).
-pub fn check_safety_of_destructor_if_necessary<'a, 'tcx>(
+/// This function is not only checking that the dropck obligations are met for
+/// the given type, but it's also currently preventing non-regular recursion in
+/// types from causing stack overflows (dropck_no_diverge_on_nonregular_*.rs).
+crate fn check_drop_obligations<'a, 'tcx>(
     rcx: &mut RegionCtxt<'a, 'tcx>,
     ty: Ty<'tcx>,
     span: Span,
     body_id: hir::HirId,
-    scope: region::Scope,
 ) -> Result<(), ErrorReported> {
-    debug!("check_safety_of_destructor_if_necessary typ: {:?} scope: {:?}",
-           ty, scope);
+    debug!("check_drop_obligations typ: {:?}", ty);
 
-    let parent_scope = match rcx.region_scope_tree.opt_encl_scope(scope) {
-        Some(parent_scope) => parent_scope,
-        // If no enclosing scope, then it must be the root scope
-        // which cannot be outlived.
-        None => return Ok(()),
-    };
-    let parent_scope = rcx.tcx.mk_region(ty::ReScope(parent_scope));
-    let origin = || infer::SubregionOrigin::SafeDestructor(span);
     let cause = &ObligationCause::misc(span, body_id);
     let infer_ok = rcx.infcx.at(cause, rcx.fcx.param_env).dropck_outlives(ty);
     debug!("dropck_outlives = {:#?}", infer_ok);
-    let kinds = rcx.fcx.register_infer_ok_obligations(infer_ok);
-    for kind in kinds {
-        match kind.unpack() {
-            GenericArgKind::Lifetime(r) => rcx.sub_regions(origin(), parent_scope, r),
-            GenericArgKind::Type(ty) => rcx.type_must_outlive(origin(), ty, parent_scope),
-            GenericArgKind::Const(_) => {
-                // Generic consts don't add constraints.
-            }
-        }
-    }
+    rcx.fcx.register_infer_ok_obligations(infer_ok);
+
     Ok(())
 }
diff --git a/src/librustc_typeck/check/regionck.rs b/src/librustc_typeck/check/regionck.rs
index 90407780a30..2f9091282b7 100644
--- a/src/librustc_typeck/check/regionck.rs
+++ b/src/librustc_typeck/check/regionck.rs
@@ -347,13 +347,7 @@ impl<'a, 'tcx> RegionCtxt<'a, 'tcx> {
         );
         self.outlives_environment
             .save_implied_bounds(body_id.hir_id);
-        self.link_fn_params(
-            region::Scope {
-                id: body.value.hir_id.local_id,
-                data: region::ScopeData::Node,
-            },
-            &body.params,
-        );
+        self.link_fn_params(&body.params);
         self.visit_body(body);
         self.visit_region_obligations(body_id.hir_id);
 
@@ -430,8 +424,8 @@ impl<'a, 'tcx> RegionCtxt<'a, 'tcx> {
 
             let typ = self.resolve_node_type(hir_id);
             let body_id = self.body_id;
-            let _ = dropck::check_safety_of_destructor_if_necessary(
-                self, typ, span, body_id, var_scope,
+            let _ = dropck::check_drop_obligations(
+                self, typ, span, body_id,
             );
         })
     }
@@ -928,29 +922,15 @@ impl<'a, 'tcx> RegionCtxt<'a, 'tcx> {
     }
 
     fn check_safety_of_rvalue_destructor_if_necessary(&mut self, cmt: &mc::cmt_<'tcx>, span: Span) {
-        if let Categorization::Rvalue(region) = cmt.cat {
-            match *region {
-                ty::ReScope(rvalue_scope) => {
-                    let typ = self.resolve_type(cmt.ty);
-                    let body_id = self.body_id;
-                    let _ = dropck::check_safety_of_destructor_if_necessary(
-                        self,
-                        typ,
-                        span,
-                        body_id,
-                        rvalue_scope,
-                    );
-                }
-                ty::ReStatic => {}
-                _ => {
-                    span_bug!(
-                        span,
-                        "unexpected rvalue region in rvalue \
-                         destructor safety checking: `{:?}`",
-                        region
-                    );
-                }
-            }
+        if let Categorization::Rvalue = cmt.cat {
+            let typ = self.resolve_type(cmt.ty);
+            let body_id = self.body_id;
+            let _ = dropck::check_drop_obligations(
+                self,
+                typ,
+                span,
+                body_id,
+            );
         }
     }
 
@@ -1074,13 +1054,11 @@ impl<'a, 'tcx> RegionCtxt<'a, 'tcx> {
     /// Computes the guarantors for any ref bindings in a match and
     /// then ensures that the lifetime of the resulting pointer is
     /// linked to the lifetime of its guarantor (if any).
-    fn link_fn_params(&self, body_scope: region::Scope, params: &[hir::Param]) {
-        debug!("regionck::link_fn_params(body_scope={:?})", body_scope);
+    fn link_fn_params(&self, params: &[hir::Param]) {
         for param in params {
             let param_ty = self.node_ty(param.hir_id);
-            let re_scope = self.tcx.mk_region(ty::ReScope(body_scope));
             let param_cmt = self.with_mc(|mc| {
-                Rc::new(mc.cat_rvalue(param.hir_id, param.pat.span, re_scope, param_ty))
+                Rc::new(mc.cat_rvalue(param.hir_id, param.pat.span, param_ty))
             });
             debug!("param_ty={:?} param_cmt={:?} param={:?}", param_ty, param_cmt, param);
             self.link_pattern(param_cmt, &param.pat);
@@ -1222,8 +1200,8 @@ impl<'a, 'tcx> RegionCtxt<'a, 'tcx> {
                 | Categorization::StaticItem
                 | Categorization::Upvar(..)
                 | Categorization::Local(..)
-                | Categorization::ThreadLocal(..)
-                | Categorization::Rvalue(..) => {
+                | Categorization::ThreadLocal
+                | Categorization::Rvalue => {
                     // These are all "base cases" with independent lifetimes
                     // that are not subject to inference
                     return;
diff --git a/src/librustc_typeck/check/upvar.rs b/src/librustc_typeck/check/upvar.rs
index 3f218e1d9fa..97e59664df0 100644
--- a/src/librustc_typeck/check/upvar.rs
+++ b/src/librustc_typeck/check/upvar.rs
@@ -325,7 +325,7 @@ impl<'a, 'tcx> InferBorrowKind<'a, 'tcx> {
             euv::Copy => {
                 return;
             }
-            euv::Move(_) => {}
+            euv::Move => {}
         }
 
         let tcx = self.fcx.tcx;
@@ -412,8 +412,8 @@ impl<'a, 'tcx> InferBorrowKind<'a, 'tcx> {
 
             Categorization::Deref(_, mc::UnsafePtr(..))
             | Categorization::StaticItem
-            | Categorization::ThreadLocal(..)
-            | Categorization::Rvalue(..)
+            | Categorization::ThreadLocal
+            | Categorization::Rvalue
             | Categorization::Local(_)
             | Categorization::Upvar(..) => {
                 return;
@@ -443,8 +443,8 @@ impl<'a, 'tcx> InferBorrowKind<'a, 'tcx> {
 
             Categorization::Deref(_, mc::UnsafePtr(..))
             | Categorization::StaticItem
-            | Categorization::ThreadLocal(..)
-            | Categorization::Rvalue(..)
+            | Categorization::ThreadLocal
+            | Categorization::Rvalue
             | Categorization::Local(_)
             | Categorization::Upvar(..) => {}
         }
@@ -586,48 +586,13 @@ impl<'a, 'tcx> InferBorrowKind<'a, 'tcx> {
 }
 
 impl<'a, 'tcx> euv::Delegate<'tcx> for InferBorrowKind<'a, 'tcx> {
-    fn consume(
-        &mut self,
-        _consume_id: hir::HirId,
-        _consume_span: Span,
-        cmt: &mc::cmt_<'tcx>,
-        mode: euv::ConsumeMode,
-    ) {
+    fn consume(&mut self, cmt: &mc::cmt_<'tcx>,mode: euv::ConsumeMode) {
         debug!("consume(cmt={:?},mode={:?})", cmt, mode);
         self.adjust_upvar_borrow_kind_for_consume(cmt, mode);
     }
 
-    fn matched_pat(
-        &mut self,
-        _matched_pat: &hir::Pat,
-        _cmt: &mc::cmt_<'tcx>,
-        _mode: euv::MatchMode,
-    ) {
-    }
-
-    fn consume_pat(
-        &mut self,
-        _consume_pat: &hir::Pat,
-        cmt: &mc::cmt_<'tcx>,
-        mode: euv::ConsumeMode,
-    ) {
-        debug!("consume_pat(cmt={:?},mode={:?})", cmt, mode);
-        self.adjust_upvar_borrow_kind_for_consume(cmt, mode);
-    }
-
-    fn borrow(
-        &mut self,
-        borrow_id: hir::HirId,
-        _borrow_span: Span,
-        cmt: &mc::cmt_<'tcx>,
-        _loan_region: ty::Region<'tcx>,
-        bk: ty::BorrowKind,
-        _loan_cause: euv::LoanCause,
-    ) {
-        debug!(
-            "borrow(borrow_id={}, cmt={:?}, bk={:?})",
-            borrow_id, cmt, bk
-        );
+    fn borrow(&mut self, cmt: &mc::cmt_<'tcx>, bk: ty::BorrowKind) {
+        debug!("borrow(cmt={:?}, bk={:?})", cmt, bk);
 
         match bk {
             ty::ImmBorrow => {}
@@ -640,15 +605,7 @@ impl<'a, 'tcx> euv::Delegate<'tcx> for InferBorrowKind<'a, 'tcx> {
         }
     }
 
-    fn decl_without_init(&mut self, _id: hir::HirId, _span: Span) {}
-
-    fn mutate(
-        &mut self,
-        _assignment_id: hir::HirId,
-        _assignment_span: Span,
-        assignee_cmt: &mc::cmt_<'tcx>,
-        _mode: euv::MutateMode,
-    ) {
+    fn mutate(&mut self, assignee_cmt: &mc::cmt_<'tcx>) {
         debug!("mutate(assignee_cmt={:?})", assignee_cmt);
 
         self.adjust_upvar_borrow_kind_for_mut(assignee_cmt);
diff --git a/src/test/ui/issues/issue-17252.stderr b/src/test/ui/issues/issue-17252.stderr
index da3e2e763af..8fd67b19d6a 100644
--- a/src/test/ui/issues/issue-17252.stderr
+++ b/src/test/ui/issues/issue-17252.stderr
@@ -1,11 +1,11 @@
-error[E0391]: cycle detected when processing `FOO`
+error[E0391]: cycle detected when const checking `FOO`
   --> $DIR/issue-17252.rs:1:20
    |
 LL | const FOO: usize = FOO;
    |                    ^^^
    |
-   = note: ...which again requires processing `FOO`, completing the cycle
-note: cycle used when processing `main::{{constant}}#0`
+   = note: ...which again requires const checking `FOO`, completing the cycle
+note: cycle used when const checking `main::{{constant}}#0`
   --> $DIR/issue-17252.rs:4:18
    |
 LL |     let _x: [u8; FOO]; // caused stack overflow prior to fix
diff --git a/src/test/ui/issues/issue-23302-1.stderr b/src/test/ui/issues/issue-23302-1.stderr
index bbdb13a9500..f2457774326 100644
--- a/src/test/ui/issues/issue-23302-1.stderr
+++ b/src/test/ui/issues/issue-23302-1.stderr
@@ -1,10 +1,10 @@
-error[E0391]: cycle detected when processing `X::A::{{constant}}#0`
+error[E0391]: cycle detected when const checking `X::A::{{constant}}#0`
   --> $DIR/issue-23302-1.rs:4:9
    |
 LL |     A = X::A as isize,
    |         ^^^^^^^^^^^^^
    |
-   = note: ...which again requires processing `X::A::{{constant}}#0`, completing the cycle
+   = note: ...which again requires const checking `X::A::{{constant}}#0`, completing the cycle
 note: cycle used when processing `X::A::{{constant}}#0`
   --> $DIR/issue-23302-1.rs:4:9
    |
diff --git a/src/test/ui/issues/issue-23302-2.stderr b/src/test/ui/issues/issue-23302-2.stderr
index 03afd82211a..c121c17b904 100644
--- a/src/test/ui/issues/issue-23302-2.stderr
+++ b/src/test/ui/issues/issue-23302-2.stderr
@@ -1,10 +1,10 @@
-error[E0391]: cycle detected when processing `Y::A::{{constant}}#0`
+error[E0391]: cycle detected when const checking `Y::A::{{constant}}#0`
   --> $DIR/issue-23302-2.rs:4:9
    |
 LL |     A = Y::B as isize,
    |         ^^^^^^^^^^^^^
    |
-   = note: ...which again requires processing `Y::A::{{constant}}#0`, completing the cycle
+   = note: ...which again requires const checking `Y::A::{{constant}}#0`, completing the cycle
 note: cycle used when processing `Y::A::{{constant}}#0`
   --> $DIR/issue-23302-2.rs:4:9
    |
diff --git a/src/test/ui/issues/issue-23302-3.stderr b/src/test/ui/issues/issue-23302-3.stderr
index a7d643987f7..0229469f041 100644
--- a/src/test/ui/issues/issue-23302-3.stderr
+++ b/src/test/ui/issues/issue-23302-3.stderr
@@ -1,26 +1,20 @@
-error[E0391]: cycle detected when const checking if rvalue is promotable to static `A`
-  --> $DIR/issue-23302-3.rs:1:1
-   |
-LL | const A: i32 = B;
-   | ^^^^^^^^^^^^^^^^^
-   |
-note: ...which requires checking which parts of `A` are promotable to static...
+error[E0391]: cycle detected when const checking `A`
   --> $DIR/issue-23302-3.rs:1:16
    |
 LL | const A: i32 = B;
    |                ^
-note: ...which requires const checking if rvalue is promotable to static `B`...
-  --> $DIR/issue-23302-3.rs:3:1
    |
-LL | const B: i32 = A;
-   | ^^^^^^^^^^^^^^^^^
-note: ...which requires checking which parts of `B` are promotable to static...
+note: ...which requires const checking `B`...
   --> $DIR/issue-23302-3.rs:3:16
    |
 LL | const B: i32 = A;
    |                ^
-   = note: ...which again requires const checking if rvalue is promotable to static `A`, completing the cycle
-   = note: cycle used when running analysis passes on this crate
+   = note: ...which again requires const checking `A`, completing the cycle
+note: cycle used when processing `A`
+  --> $DIR/issue-23302-3.rs:1:1
+   |
+LL | const A: i32 = B;
+   | ^^^^^^^^^^^^^^^^^
 
 error: aborting due to previous error
 
diff --git a/src/test/ui/issues/issue-36163.stderr b/src/test/ui/issues/issue-36163.stderr
index 50e8cf6e88c..3866243914b 100644
--- a/src/test/ui/issues/issue-36163.stderr
+++ b/src/test/ui/issues/issue-36163.stderr
@@ -1,15 +1,15 @@
-error[E0391]: cycle detected when processing `Foo::B::{{constant}}#0`
+error[E0391]: cycle detected when const checking `Foo::B::{{constant}}#0`
   --> $DIR/issue-36163.rs:4:9
    |
 LL |     B = A,
    |         ^
    |
-note: ...which requires processing `A`...
+note: ...which requires const checking `A`...
   --> $DIR/issue-36163.rs:1:18
    |
 LL | const A: isize = Foo::B as isize;
    |                  ^^^^^^^^^^^^^^^
-   = note: ...which again requires processing `Foo::B::{{constant}}#0`, completing the cycle
+   = note: ...which again requires const checking `Foo::B::{{constant}}#0`, completing the cycle
 note: cycle used when processing `Foo::B::{{constant}}#0`
   --> $DIR/issue-36163.rs:4:9
    |