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 https://github.com/rust-lang/project-rfc-2229/issues/5

Closes https://github.com/rust-lang/project-rfc-2229/issues/3

Co-authored-by: Aman Arora <me@aman-arora.com>
Co-authored-by: Roxane Fruytier <roxane.fruytier@hotmail.com>

4 files changed, 38 insertions, 36 deletions

diff --git a/clippy_lints/src/escape.rs b/clippy_lints/src/escape.rs
index 7227683aa5a..59af475af17 100644
--- a/clippy_lints/src/escape.rs
+++ b/clippy_lints/src/escape.rs
@@ -6,7 +6,7 @@ use rustc_middle::ty::{self, Ty};
 use rustc_session::{declare_tool_lint, impl_lint_pass};
 use rustc_span::source_map::Span;
 use rustc_target::abi::LayoutOf;
-use rustc_typeck::expr_use_visitor::{ConsumeMode, Delegate, ExprUseVisitor, Place, PlaceBase};
+use rustc_typeck::expr_use_visitor::{ConsumeMode, Delegate, ExprUseVisitor, PlaceWithHirId, PlaceBase};
 
 use crate::utils::span_lint;
 
@@ -112,9 +112,9 @@ fn is_argument(map: rustc_middle::hir::map::Map<'_>, id: HirId) -> bool {
 }
 
 impl<'a, 'tcx> Delegate<'tcx> for EscapeDelegate<'a, 'tcx> {
-    fn consume(&mut self, cmt: &Place<'tcx>, mode: ConsumeMode) {
-        if cmt.projections.is_empty() {
-            if let PlaceBase::Local(lid) = cmt.base {
+    fn consume(&mut self, cmt: &PlaceWithHirId<'tcx>, mode: ConsumeMode) {
+        if cmt.place.projections.is_empty() {
+            if let PlaceBase::Local(lid) = cmt.place.base {
                 if let ConsumeMode::Move = mode {
                     // moved out or in. clearly can't be localized
                     self.set.remove(&lid);
@@ -132,16 +132,16 @@ impl<'a, 'tcx> Delegate<'tcx> for EscapeDelegate<'a, 'tcx> {
         }
     }
 
-    fn borrow(&mut self, cmt: &Place<'tcx>, _: ty::BorrowKind) {
-        if cmt.projections.is_empty() {
-            if let PlaceBase::Local(lid) = cmt.base {
+    fn borrow(&mut self, cmt: &PlaceWithHirId<'tcx>, _: ty::BorrowKind) {
+        if cmt.place.projections.is_empty() {
+            if let PlaceBase::Local(lid) = cmt.place.base {
                 self.set.remove(&lid);
             }
         }
     }
 
-    fn mutate(&mut self, cmt: &Place<'tcx>) {
-        if cmt.projections.is_empty() {
+    fn mutate(&mut self, cmt: &PlaceWithHirId<'tcx>) {
+        if cmt.place.projections.is_empty() {
             let map = &self.cx.tcx.hir();
             if is_argument(*map, cmt.hir_id) {
                 // Skip closure arguments
@@ -150,7 +150,7 @@ impl<'a, 'tcx> Delegate<'tcx> for EscapeDelegate<'a, 'tcx> {
                     return;
                 }
 
-                if is_non_trait_box(cmt.ty) && !self.is_large_box(cmt.ty) {
+                if is_non_trait_box(cmt.place.ty) && !self.is_large_box(cmt.place.ty) {
                     self.set.insert(cmt.hir_id);
                 }
                 return;
diff --git a/clippy_lints/src/loops.rs b/clippy_lints/src/loops.rs
index 771bc8d0558..83093ec51bd 100644
--- a/clippy_lints/src/loops.rs
+++ b/clippy_lints/src/loops.rs
@@ -28,7 +28,7 @@ use rustc_middle::ty::{self, Ty, TyS};
 use rustc_session::{declare_lint_pass, declare_tool_lint};
 use rustc_span::source_map::Span;
 use rustc_span::symbol::Symbol;
-use rustc_typeck::expr_use_visitor::{ConsumeMode, Delegate, ExprUseVisitor, Place, PlaceBase};
+use rustc_typeck::expr_use_visitor::{ConsumeMode, Delegate, ExprUseVisitor, PlaceWithHirId, PlaceBase};
 use std::iter::{once, Iterator};
 use std::mem;
 
@@ -1489,42 +1489,43 @@ fn check_for_loop_over_map_kv<'a, 'tcx>(
     }
 }
 
-struct MutatePairDelegate {
+struct MutatePairDelegate<'a, 'tcx> {
+    cx: &'a LateContext<'a, 'tcx>,
     hir_id_low: Option<HirId>,
     hir_id_high: Option<HirId>,
     span_low: Option<Span>,
     span_high: Option<Span>,
 }
 
-impl<'tcx> Delegate<'tcx> for MutatePairDelegate {
-    fn consume(&mut self, _: &Place<'tcx>, _: ConsumeMode) {}
+impl<'a, 'tcx> Delegate<'tcx> for MutatePairDelegate<'a, 'tcx> {
+    fn consume(&mut self, _: &PlaceWithHirId<'tcx>, _: ConsumeMode) {}
 
-    fn borrow(&mut self, cmt: &Place<'tcx>, bk: ty::BorrowKind) {
+    fn borrow(&mut self, cmt: &PlaceWithHirId<'tcx>, bk: ty::BorrowKind) {
         if let ty::BorrowKind::MutBorrow = bk {
-            if let PlaceBase::Local(id) = cmt.base {
+            if let PlaceBase::Local(id) = cmt.place.base {
                 if Some(id) == self.hir_id_low {
-                    self.span_low = Some(cmt.span)
+                    self.span_low = Some(self.cx.tcx.hir().span(cmt.hir_id))
                 }
                 if Some(id) == self.hir_id_high {
-                    self.span_high = Some(cmt.span)
+                    self.span_high = Some(self.cx.tcx.hir().span(cmt.hir_id))
                 }
             }
         }
     }
 
-    fn mutate(&mut self, cmt: &Place<'tcx>) {
-        if let PlaceBase::Local(id) = cmt.base {
+    fn mutate(&mut self, cmt: &PlaceWithHirId<'tcx>) {
+        if let PlaceBase::Local(id) = cmt.place.base {
             if Some(id) == self.hir_id_low {
-                self.span_low = Some(cmt.span)
+                self.span_low = Some(self.cx.tcx.hir().span(cmt.hir_id))
             }
             if Some(id) == self.hir_id_high {
-                self.span_high = Some(cmt.span)
+                self.span_high = Some(self.cx.tcx.hir().span(cmt.hir_id))
             }
         }
     }
 }
 
-impl<'tcx> MutatePairDelegate {
+impl<'a, 'tcx> MutatePairDelegate<'a, 'tcx> {
     fn mutation_span(&self) -> (Option<Span>, Option<Span>) {
         (self.span_low, self.span_high)
     }
@@ -1579,12 +1580,13 @@ fn check_for_mutability(cx: &LateContext<'_, '_>, bound: &Expr<'_>) -> Option<Hi
     None
 }
 
-fn check_for_mutation(
-    cx: &LateContext<'_, '_>,
+fn check_for_mutation<'a, 'tcx> (
+    cx: &LateContext<'a, 'tcx>,
     body: &Expr<'_>,
     bound_ids: &[Option<HirId>],
 ) -> (Option<Span>, Option<Span>) {
     let mut delegate = MutatePairDelegate {
+        cx: cx,
         hir_id_low: bound_ids[0],
         hir_id_high: bound_ids[1],
         span_low: None,
diff --git a/clippy_lints/src/needless_pass_by_value.rs b/clippy_lints/src/needless_pass_by_value.rs
index 218b0d27f74..ca87deac989 100644
--- a/clippy_lints/src/needless_pass_by_value.rs
+++ b/clippy_lints/src/needless_pass_by_value.rs
@@ -326,21 +326,21 @@ struct MovedVariablesCtxt {
 }
 
 impl MovedVariablesCtxt {
-    fn move_common(&mut self, cmt: &euv::Place<'_>) {
-        if let euv::PlaceBase::Local(vid) = cmt.base {
+    fn move_common(&mut self, cmt: &euv::PlaceWithHirId<'_>) {
+        if let euv::PlaceBase::Local(vid) = cmt.place.base {
             self.moved_vars.insert(vid);
         }
     }
 }
 
 impl<'tcx> euv::Delegate<'tcx> for MovedVariablesCtxt {
-    fn consume(&mut self, cmt: &euv::Place<'tcx>, mode: euv::ConsumeMode) {
+    fn consume(&mut self, cmt: &euv::PlaceWithHirId<'tcx>, mode: euv::ConsumeMode) {
         if let euv::ConsumeMode::Move = mode {
             self.move_common(cmt);
         }
     }
 
-    fn borrow(&mut self, _: &euv::Place<'tcx>, _: ty::BorrowKind) {}
+    fn borrow(&mut self, _: &euv::PlaceWithHirId<'tcx>, _: ty::BorrowKind) {}
 
-    fn mutate(&mut self, _: &euv::Place<'tcx>) {}
+    fn mutate(&mut self, _: &euv::PlaceWithHirId<'tcx>) {}
 }
diff --git a/clippy_lints/src/utils/usage.rs b/clippy_lints/src/utils/usage.rs
index 904d948ad29..6a7a1f1ceaa 100644
--- a/clippy_lints/src/utils/usage.rs
+++ b/clippy_lints/src/utils/usage.rs
@@ -8,7 +8,7 @@ use rustc_lint::LateContext;
 use rustc_middle::hir::map::Map;
 use rustc_middle::ty;
 use rustc_span::symbol::{Ident, Symbol};
-use rustc_typeck::expr_use_visitor::{ConsumeMode, Delegate, ExprUseVisitor, Place, PlaceBase};
+use rustc_typeck::expr_use_visitor::{ConsumeMode, Delegate, ExprUseVisitor, PlaceWithHirId, PlaceBase};
 
 /// Returns a set of mutated local variable IDs, or `None` if mutations could not be determined.
 pub fn mutated_variables<'a, 'tcx>(expr: &'tcx Expr<'_>, cx: &'a LateContext<'a, 'tcx>) -> Option<FxHashSet<HirId>> {
@@ -46,8 +46,8 @@ struct MutVarsDelegate {
 
 impl<'tcx> MutVarsDelegate {
     #[allow(clippy::similar_names)]
-    fn update(&mut self, cat: &Place<'tcx>) {
-        match cat.base {
+    fn update(&mut self, cat: &PlaceWithHirId<'tcx>) {
+        match cat.place.base {
             PlaceBase::Local(id) => {
                 self.used_mutably.insert(id);
             },
@@ -63,15 +63,15 @@ impl<'tcx> MutVarsDelegate {
 }
 
 impl<'tcx> Delegate<'tcx> for MutVarsDelegate {
-    fn consume(&mut self, _: &Place<'tcx>, _: ConsumeMode) {}
+    fn consume(&mut self, _: &PlaceWithHirId<'tcx>, _: ConsumeMode) {}
 
-    fn borrow(&mut self, cmt: &Place<'tcx>, bk: ty::BorrowKind) {
+    fn borrow(&mut self, cmt: &PlaceWithHirId<'tcx>, bk: ty::BorrowKind) {
         if let ty::BorrowKind::MutBorrow = bk {
             self.update(&cmt)
         }
     }
 
-    fn mutate(&mut self, cmt: &Place<'tcx>) {
+    fn mutate(&mut self, cmt: &PlaceWithHirId<'tcx>) {
         self.update(&cmt)
     }
 }