Refactor hir::Place

For the following code
```rust
let c = || bar(foo.x, foo.x)
```

We generate two different `hir::Place`s for both `foo.x`.
Handling this adds overhead for analysis we need to do for RFC 2229.

We also want to store type information at each Projection to support
analysis as part of the RFC. This resembles what we have for
`mir::Place`

This commit modifies the Place as follows:
- Rename to `PlaceWithHirId`, where there `hir_id` is that of the
expressioin.
- Move any other information that describes the access out to another
struct now called `Place`.
- Removed `Span`, it can be accessed using the [hir
API](https://doc.rust-lang.org/nightly/nightly-rustc/rustc_middle/hir/map/struct.Map.html#method.span)
- Modify `Projection` to be a strucutre of its own, that currently only
contains the `ProjectionKind`.

Adding type information to projections wil be completed as part of rust-lang/project-rfc-2229#5

Closes rust-lang/project-rfc-2229#3

Co-authored-by: Aman Arora <[email protected]>
Co-authored-by: Roxane Fruytier <[email protected]>

Author: arora-aman

src/librustc_typeck/check/regionck.rs

@@ -439,7 +439,10 @@ impl<'a, 'tcx> RegionCtxt<'a, 'tcx> {
 
     /// Invoked on any adjustments that occur. Checks that if this is a region pointer being
     /// dereferenced, the lifetime of the pointer includes the deref expr.
-    fn constrain_adjustments(&mut self, expr: &hir::Expr<'_>) -> mc::McResult<mc::Place<'tcx>> {
+    fn constrain_adjustments(
+        &mut self,
+        expr: &hir::Expr<'_>,
+    ) -> mc::McResult<mc::PlaceWithHirId<'tcx>> {
         debug!("constrain_adjustments(expr={:?})", expr);
 
         let mut place = self.with_mc(|mc| mc.cat_expr_unadjusted(expr))?;
@@ -480,12 +483,12 @@ impl<'a, 'tcx> RegionCtxt<'a, 'tcx> {
 
     fn check_safety_of_rvalue_destructor_if_necessary(
         &mut self,
-        place: &mc::Place<'tcx>,
+        place_with_id: &mc::PlaceWithHirId<'tcx>,
         span: Span,
     ) {
-        if let mc::PlaceBase::Rvalue = place.base {
-            if place.projections.is_empty() {
-                let typ = self.resolve_type(place.ty);
+        if let mc::PlaceBase::Rvalue = place_with_id.place.base {
+            if place_with_id.place.projections.is_empty() {
+                let typ = self.resolve_type(place_with_id.place.ty);
                 let body_id = self.body_id;
                 let _ = dropck::check_drop_obligations(self, typ, span, body_id);
             }
@@ -570,7 +573,7 @@ impl<'a, 'tcx> RegionCtxt<'a, 'tcx> {
 
     /// Link lifetimes of any ref bindings in `root_pat` to the pointers found
     /// in the discriminant, if needed.
-    fn link_pattern(&self, discr_cmt: mc::Place<'tcx>, root_pat: &hir::Pat<'_>) {
+    fn link_pattern(&self, discr_cmt: mc::PlaceWithHirId<'tcx>, root_pat: &hir::Pat<'_>) {
         debug!("link_pattern(discr_cmt={:?}, root_pat={:?})", discr_cmt, root_pat);
         ignore_err!(self.with_mc(|mc| {
             mc.cat_pattern(discr_cmt, root_pat, |sub_cmt, hir::Pat { kind, span, hir_id }| {
@@ -591,7 +594,7 @@ impl<'a, 'tcx> RegionCtxt<'a, 'tcx> {
     fn link_autoref(
         &self,
         expr: &hir::Expr<'_>,
-        expr_cmt: &mc::Place<'tcx>,
+        expr_cmt: &mc::PlaceWithHirId<'tcx>,
         autoref: &adjustment::AutoBorrow<'tcx>,
     ) {
         debug!("link_autoref(autoref={:?}, expr_cmt={:?})", autoref, expr_cmt);
@@ -612,7 +615,7 @@ impl<'a, 'tcx> RegionCtxt<'a, 'tcx> {
         span: Span,
         id: hir::HirId,
         mutbl: hir::Mutability,
-        cmt_borrowed: &mc::Place<'tcx>,
+        cmt_borrowed: &mc::PlaceWithHirId<'tcx>,
     ) {
         debug!(
             "link_region_from_node_type(id={:?}, mutbl={:?}, cmt_borrowed={:?})",
@@ -635,12 +638,12 @@ impl<'a, 'tcx> RegionCtxt<'a, 'tcx> {
         span: Span,
         borrow_region: ty::Region<'tcx>,
         borrow_kind: ty::BorrowKind,
-        borrow_place: &mc::Place<'tcx>,
+        borrow_place: &mc::PlaceWithHirId<'tcx>,
     ) {
-        let origin = infer::DataBorrowed(borrow_place.ty, span);
-        self.type_must_outlive(origin, borrow_place.ty, borrow_region);
+        let origin = infer::DataBorrowed(borrow_place.place.ty, span);
+        self.type_must_outlive(origin, borrow_place.place.ty, borrow_region);
 
-        for pointer_ty in borrow_place.deref_tys() {
+        for pointer_ty in borrow_place.place.deref_tys() {
             debug!(
                 "link_region(borrow_region={:?}, borrow_kind={:?}, pointer_ty={:?})",
                 borrow_region, borrow_kind, borrow_place
@@ -656,7 +659,7 @@ impl<'a, 'tcx> RegionCtxt<'a, 'tcx> {
                 _ => assert!(pointer_ty.is_box(), "unexpected built-in deref type {}", pointer_ty),
             }
         }
-        if let mc::PlaceBase::Upvar(upvar_id) = borrow_place.base {
+        if let mc::PlaceBase::Upvar(upvar_id) = borrow_place.place.base {
             self.link_upvar_region(span, borrow_region, upvar_id);
         }
     }

src/librustc_typeck/check/upvar.rs

@@ -270,10 +270,13 @@ struct InferBorrowKind<'a, 'tcx> {
 impl<'a, 'tcx> InferBorrowKind<'a, 'tcx> {
     fn adjust_upvar_borrow_kind_for_consume(
         &mut self,
-        place: &mc::Place<'tcx>,
+        place_with_id: &mc::PlaceWithHirId<'tcx>,
         mode: euv::ConsumeMode,
     ) {
-        debug!("adjust_upvar_borrow_kind_for_consume(place={:?}, mode={:?})", place, mode);
+        debug!(
+            "adjust_upvar_borrow_kind_for_consume(place_with_id={:?}, mode={:?})",
+            place_with_id, mode
+        );
 
         // we only care about moves
         match mode {
@@ -284,7 +287,7 @@ impl<'a, 'tcx> InferBorrowKind<'a, 'tcx> {
         }
 
         let tcx = self.fcx.tcx;
-        let upvar_id = if let PlaceBase::Upvar(upvar_id) = place.base {
+        let upvar_id = if let PlaceBase::Upvar(upvar_id) = place_with_id.place.base {
             upvar_id
         } else {
             return;
@@ -296,22 +299,22 @@ impl<'a, 'tcx> InferBorrowKind<'a, 'tcx> {
         self.adjust_closure_kind(
             upvar_id.closure_expr_id,
             ty::ClosureKind::FnOnce,
-            place.span,
+            tcx.hir().span(place_with_id.hir_id),
             var_name(tcx, upvar_id.var_path.hir_id),
         );
 
         self.adjust_upvar_captures.insert(upvar_id, ty::UpvarCapture::ByValue);
     }
 
-    /// Indicates that `place` is being directly mutated (e.g., assigned
+    /// Indicates that `place_with_id` is being directly mutated (e.g., assigned
     /// to). If the place is based on a by-ref upvar, this implies that
     /// the upvar must be borrowed using an `&mut` borrow.
-    fn adjust_upvar_borrow_kind_for_mut(&mut self, place: &mc::Place<'tcx>) {
-        debug!("adjust_upvar_borrow_kind_for_mut(place={:?})", place);
+    fn adjust_upvar_borrow_kind_for_mut(&mut self, place_with_id: &mc::PlaceWithHirId<'tcx>) {
+        debug!("adjust_upvar_borrow_kind_for_mut(place_with_id={:?})", place_with_id);
 
-        if let PlaceBase::Upvar(upvar_id) = place.base {
+        if let PlaceBase::Upvar(upvar_id) = place_with_id.place.base {
             let mut borrow_kind = ty::MutBorrow;
-            for pointer_ty in place.deref_tys() {
+            for pointer_ty in place_with_id.place.deref_tys() {
                 match pointer_ty.kind {
                     // Raw pointers don't inherit mutability.
                     ty::RawPtr(_) => return,
@@ -323,20 +326,28 @@ impl<'a, 'tcx> InferBorrowKind<'a, 'tcx> {
                     _ => (),
                 }
             }
-            self.adjust_upvar_deref(upvar_id, place.span, borrow_kind);
+            self.adjust_upvar_deref(
+                upvar_id,
+                self.fcx.tcx.hir().span(place_with_id.hir_id),
+                borrow_kind,
+            );
         }
     }
 
-    fn adjust_upvar_borrow_kind_for_unique(&mut self, place: &mc::Place<'tcx>) {
-        debug!("adjust_upvar_borrow_kind_for_unique(place={:?})", place);
+    fn adjust_upvar_borrow_kind_for_unique(&mut self, place_with_id: &mc::PlaceWithHirId<'tcx>) {
+        debug!("adjust_upvar_borrow_kind_for_unique(place_with_id={:?})", place_with_id);
 
-        if let PlaceBase::Upvar(upvar_id) = place.base {
-            if place.deref_tys().any(ty::TyS::is_unsafe_ptr) {
+        if let PlaceBase::Upvar(upvar_id) = place_with_id.place.base {
+            if place_with_id.place.deref_tys().any(ty::TyS::is_unsafe_ptr) {
                 // Raw pointers don't inherit mutability.
                 return;
             }
             // for a borrowed pointer to be unique, its base must be unique
-            self.adjust_upvar_deref(upvar_id, place.span, ty::UniqueImmBorrow);
+            self.adjust_upvar_deref(
+                upvar_id,
+                self.fcx.tcx.hir().span(place_with_id.hir_id),
+                ty::UniqueImmBorrow,
+            );
         }
     }
 
@@ -453,26 +464,26 @@ impl<'a, 'tcx> InferBorrowKind<'a, 'tcx> {
 }
 
 impl<'a, 'tcx> euv::Delegate<'tcx> for InferBorrowKind<'a, 'tcx> {
-    fn consume(&mut self, place: &mc::Place<'tcx>, mode: euv::ConsumeMode) {
-        debug!("consume(place={:?},mode={:?})", place, mode);
-        self.adjust_upvar_borrow_kind_for_consume(place, mode);
+    fn consume(&mut self, place_with_id: &mc::PlaceWithHirId<'tcx>, mode: euv::ConsumeMode) {
+        debug!("consume(place_with_id={:?},mode={:?})", place_with_id, mode);
+        self.adjust_upvar_borrow_kind_for_consume(place_with_id, mode);
     }
 
-    fn borrow(&mut self, place: &mc::Place<'tcx>, bk: ty::BorrowKind) {
-        debug!("borrow(place={:?}, bk={:?})", place, bk);
+    fn borrow(&mut self, place_with_id: &mc::PlaceWithHirId<'tcx>, bk: ty::BorrowKind) {
+        debug!("borrow(place_with_id={:?}, bk={:?})", place_with_id, bk);
 
         match bk {
             ty::ImmBorrow => {}
             ty::UniqueImmBorrow => {
-                self.adjust_upvar_borrow_kind_for_unique(place);
+                self.adjust_upvar_borrow_kind_for_unique(place_with_id);
             }
             ty::MutBorrow => {
-                self.adjust_upvar_borrow_kind_for_mut(place);
+                self.adjust_upvar_borrow_kind_for_mut(place_with_id);
             }
         }
     }
 
-    fn mutate(&mut self, assignee_place: &mc::Place<'tcx>) {
+    fn mutate(&mut self, assignee_place: &mc::PlaceWithHirId<'tcx>) {
         debug!("mutate(assignee_place={:?})", assignee_place);
 
         self.adjust_upvar_borrow_kind_for_mut(assignee_place);

src/librustc_typeck/expr_use_visitor.rs

@@ -5,7 +5,7 @@
 pub use self::ConsumeMode::*;
 
 // Export these here so that Clippy can use them.
-pub use mc::{Place, PlaceBase, Projection};
+pub use mc::{PlaceBase, PlaceWithHirId, Projection};
 
 use rustc_hir as hir;
 use rustc_hir::def::Res;
@@ -25,13 +25,13 @@ use rustc_span::Span;
 pub trait Delegate<'tcx> {
     // The value found at `place` is either copied or moved, depending
     // on mode.
-    fn consume(&mut self, place: &mc::Place<'tcx>, mode: ConsumeMode);
+    fn consume(&mut self, place_with_id: &mc::PlaceWithHirId<'tcx>, mode: ConsumeMode);
 
     // The value found at `place` is being borrowed with kind `bk`.
-    fn borrow(&mut self, place: &mc::Place<'tcx>, bk: ty::BorrowKind);
+    fn borrow(&mut self, place_with_id: &mc::PlaceWithHirId<'tcx>, bk: ty::BorrowKind);
 
-    // The path at `place` is being assigned to.
-    fn mutate(&mut self, assignee_place: &mc::Place<'tcx>);
+    // The path at `place_with_id` is being assigned to.
+    fn mutate(&mut self, assignee_place: &mc::PlaceWithHirId<'tcx>);
 }
 
 #[derive(Copy, Clone, PartialEq, Debug)]
@@ -113,11 +113,11 @@ impl<'a, 'tcx> ExprUseVisitor<'a, 'tcx> {
         self.mc.tcx()
     }
 
-    fn delegate_consume(&mut self, place: &Place<'tcx>) {
-        debug!("delegate_consume(place={:?})", place);
+    fn delegate_consume(&mut self, place_with_id: &PlaceWithHirId<'tcx>) {
+        debug!("delegate_consume(place_with_id={:?})", place_with_id);
 
-        let mode = copy_or_move(&self.mc, place);
-        self.delegate.consume(place, mode);
+        let mode = copy_or_move(&self.mc, place_with_id);
+        self.delegate.consume(place_with_id, mode);
     }
 
     fn consume_exprs(&mut self, exprs: &[hir::Expr<'_>]) {
@@ -129,22 +129,22 @@ impl<'a, 'tcx> ExprUseVisitor<'a, 'tcx> {
     pub fn consume_expr(&mut self, expr: &hir::Expr<'_>) {
         debug!("consume_expr(expr={:?})", expr);
 
-        let place = return_if_err!(self.mc.cat_expr(expr));
-        self.delegate_consume(&place);
+        let place_with_id = return_if_err!(self.mc.cat_expr(expr));
+        self.delegate_consume(&place_with_id);
         self.walk_expr(expr);
     }
 
     fn mutate_expr(&mut self, expr: &hir::Expr<'_>) {
-        let place = return_if_err!(self.mc.cat_expr(expr));
-        self.delegate.mutate(&place);
+        let place_with_id = return_if_err!(self.mc.cat_expr(expr));
+        self.delegate.mutate(&place_with_id);
         self.walk_expr(expr);
     }
 
     fn borrow_expr(&mut self, expr: &hir::Expr<'_>, bk: ty::BorrowKind) {
         debug!("borrow_expr(expr={:?}, bk={:?})", expr, bk);
 
-        let place = return_if_err!(self.mc.cat_expr(expr));
-        self.delegate.borrow(&place, bk);
+        let place_with_id = return_if_err!(self.mc.cat_expr(expr));
+        self.delegate.borrow(&place_with_id, bk);
 
         self.walk_expr(expr)
     }
@@ -384,7 +384,7 @@ impl<'a, 'tcx> ExprUseVisitor<'a, 'tcx> {
 
         // Select just those fields of the `with`
         // expression that will actually be used
-        match with_place.ty.kind {
+        match with_place.place.ty.kind {
             ty::Adt(adt, substs) if adt.is_struct() => {
                 // Consume those fields of the with expression that are needed.
                 for (f_index, with_field) in adt.non_enum_variant().fields.iter().enumerate() {
@@ -422,14 +422,14 @@ impl<'a, 'tcx> ExprUseVisitor<'a, 'tcx> {
     // process.
     fn walk_adjustment(&mut self, expr: &hir::Expr<'_>) {
         let adjustments = self.mc.tables.expr_adjustments(expr);
-        let mut place = return_if_err!(self.mc.cat_expr_unadjusted(expr));
+        let mut place_with_id = return_if_err!(self.mc.cat_expr_unadjusted(expr));
         for adjustment in adjustments {
             debug!("walk_adjustment expr={:?} adj={:?}", expr, adjustment);
             match adjustment.kind {
                 adjustment::Adjust::NeverToAny | adjustment::Adjust::Pointer(_) => {
                     // Creating a closure/fn-pointer or unsizing consumes
                     // the input and stores it into the resulting rvalue.
-                    self.delegate_consume(&place);
+                    self.delegate_consume(&place_with_id);
                 }
 
                 adjustment::Adjust::Deref(None) => {}
@@ -441,14 +441,15 @@ 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(&place, bk);
+                    self.delegate.borrow(&place_with_id, bk);
                 }
 
                 adjustment::Adjust::Borrow(ref autoref) => {
-                    self.walk_autoref(expr, &place, autoref);
+                    self.walk_autoref(expr, &place_with_id, autoref);
                 }
             }
-            place = return_if_err!(self.mc.cat_expr_adjusted(expr, place, &adjustment));
+            place_with_id =
+                return_if_err!(self.mc.cat_expr_adjusted(expr, place_with_id, &adjustment));
         }
     }
 
@@ -458,7 +459,7 @@ impl<'a, 'tcx> ExprUseVisitor<'a, 'tcx> {
     fn walk_autoref(
         &mut self,
         expr: &hir::Expr<'_>,
-        base_place: &mc::Place<'tcx>,
+        base_place: &mc::PlaceWithHirId<'tcx>,
         autoref: &adjustment::AutoBorrow<'tcx>,
     ) {
         debug!(
@@ -479,7 +480,7 @@ impl<'a, 'tcx> ExprUseVisitor<'a, 'tcx> {
         }
     }
 
-    fn walk_arm(&mut self, discr_place: &Place<'tcx>, arm: &hir::Arm<'_>) {
+    fn walk_arm(&mut self, discr_place: &PlaceWithHirId<'tcx>, arm: &hir::Arm<'_>) {
         self.walk_pat(discr_place, &arm.pat);
 
         if let Some(hir::Guard::If(ref e)) = arm.guard {
@@ -491,12 +492,12 @@ 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, discr_place: &Place<'tcx>, pat: &hir::Pat<'_>) {
+    fn walk_irrefutable_pat(&mut self, discr_place: &PlaceWithHirId<'tcx>, pat: &hir::Pat<'_>) {
         self.walk_pat(discr_place, pat);
     }
 
     /// The core driver for walking a pattern
-    fn walk_pat(&mut self, discr_place: &Place<'tcx>, pat: &hir::Pat<'_>) {
+    fn walk_pat(&mut self, discr_place: &PlaceWithHirId<'tcx>, pat: &hir::Pat<'_>) {
         debug!("walk_pat(discr_place={:?}, pat={:?})", discr_place, pat);
 
         let tcx = self.tcx();
@@ -569,7 +570,7 @@ impl<'a, 'tcx> ExprUseVisitor<'a, 'tcx> {
         closure_hir_id: hir::HirId,
         closure_span: Span,
         var_id: hir::HirId,
-    ) -> mc::McResult<mc::Place<'tcx>> {
+    ) -> mc::McResult<mc::PlaceWithHirId<'tcx>> {
         // Create the place for the variable being borrowed, from the
         // perspective of the creator (parent) of the closure.
         let var_ty = self.mc.node_ty(var_id)?;
@@ -579,7 +580,14 @@ impl<'a, 'tcx> ExprUseVisitor<'a, 'tcx> {
 
 fn copy_or_move<'a, 'tcx>(
     mc: &mc::MemCategorizationContext<'a, 'tcx>,
-    place: &Place<'tcx>,
+    place_with_id: &PlaceWithHirId<'tcx>,
 ) -> ConsumeMode {
-    if !mc.type_is_copy_modulo_regions(place.ty, place.span) { Move } else { Copy }
+    if !mc.type_is_copy_modulo_regions(
+        place_with_id.place.ty,
+        mc.tcx().hir().span(place_with_id.hir_id),
+    ) {
+        Move
+    } else {
+        Copy
+    }
 }