try to fix issue 57017, but not quite there yet

Co-authored-by: Eric Holk <eric@theincredibleholk.org>

Author: nikomatsakis

compiler/rustc_typeck/src/check/generator_interior.rs

@@ -13,7 +13,7 @@ use rustc_hir::def_id::DefId;
 use rustc_hir::hir_id::HirIdSet;
 use rustc_hir::intravisit::{self, Visitor};
 use rustc_hir::{Arm, Expr, ExprKind, Guard, HirId, Pat, PatKind};
-use rustc_middle::middle::region::{self, YieldData};
+use rustc_middle::middle::region::{self, Scope, ScopeData, YieldData};
 use rustc_middle::ty::{self, Ty, TyCtxt};
 use rustc_span::symbol::sym;
 use rustc_span::Span;
@@ -369,7 +369,17 @@ impl<'a, 'tcx> Visitor<'tcx> for InteriorVisitor<'a, 'tcx> {
 
         self.expr_count += 1;
 
-        let scope = self.region_scope_tree.temporary_scope(expr.hir_id.local_id);
+        debug!("is_borrowed_temporary: {:?}", self.drop_ranges.is_borrowed_temporary(expr));
+
+        let scope = if self.drop_ranges.is_borrowed_temporary(expr) {
+            self.region_scope_tree.temporary_scope(expr.hir_id.local_id)
+        } else {
+            debug!("parent_node: {:?}", self.fcx.tcx.hir().find_parent_node(expr.hir_id));
+            match self.fcx.tcx.hir().find_parent_node(expr.hir_id) {
+                Some(parent) => Some(Scope { id: parent.local_id, data: ScopeData::Node }),
+                None => self.region_scope_tree.temporary_scope(expr.hir_id.local_id),
+            }
+        };
 
         // If there are adjustments, then record the final type --
         // this is the actual value that is being produced.

compiler/rustc_typeck/src/check/generator_interior/drop_ranges.rs

@@ -18,6 +18,7 @@ use crate::check::FnCtxt;
 use hir::def_id::DefId;
 use hir::{Body, HirId, HirIdMap, Node};
 use rustc_data_structures::fx::FxHashMap;
+use rustc_data_structures::stable_set::FxHashSet;
 use rustc_hir as hir;
 use rustc_index::bit_set::BitSet;
 use rustc_index::vec::IndexVec;
@@ -41,7 +42,7 @@ pub fn compute_drop_ranges<'a, 'tcx>(
         let consumed_borrowed_places = find_consumed_and_borrowed(fcx, def_id, body);
 
         let num_exprs = fcx.tcx.region_scope_tree(def_id).body_expr_count(body.id()).unwrap_or(0);
-        let mut drop_ranges = build_control_flow_graph(
+        let (mut drop_ranges, borrowed_temporaries) = build_control_flow_graph(
             fcx.tcx.hir(),
             fcx.tcx,
             &fcx.typeck_results.borrow(),
@@ -52,11 +53,20 @@ pub fn compute_drop_ranges<'a, 'tcx>(
 
         drop_ranges.propagate_to_fixpoint();
 
-        DropRanges { tracked_value_map: drop_ranges.tracked_value_map, nodes: drop_ranges.nodes }
+        debug!("borrowed_temporaries = {borrowed_temporaries:?}");
+        DropRanges {
+            tracked_value_map: drop_ranges.tracked_value_map,
+            nodes: drop_ranges.nodes,
+            borrowed_temporaries: Some(borrowed_temporaries),
+        }
     } else {
         // If drop range tracking is not enabled, skip all the analysis and produce an
         // empty set of DropRanges.
-        DropRanges { tracked_value_map: FxHashMap::default(), nodes: IndexVec::new() }
+        DropRanges {
+            tracked_value_map: FxHashMap::default(),
+            nodes: IndexVec::new(),
+            borrowed_temporaries: None,
+        }
     }
 }
 
@@ -161,6 +171,7 @@ impl TryFrom<&PlaceWithHirId<'_>> for TrackedValue {
 pub struct DropRanges {
     tracked_value_map: FxHashMap<TrackedValue, TrackedValueIndex>,
     nodes: IndexVec<PostOrderId, NodeInfo>,
+    borrowed_temporaries: Option<FxHashSet<HirId>>,
 }
 
 impl DropRanges {
@@ -174,6 +185,10 @@ impl DropRanges {
             })
     }
 
+    pub fn is_borrowed_temporary(&self, expr: &hir::Expr<'_>) -> bool {
+        if let Some(b) = &self.borrowed_temporaries { b.contains(&expr.hir_id) } else { true }
+    }
+
     /// Returns a reference to the NodeInfo for a node, panicking if it does not exist
     fn expect_node(&self, id: PostOrderId) -> &NodeInfo {
         &self.nodes[id]

compiler/rustc_typeck/src/check/generator_interior/drop_ranges/cfg_build.rs

@@ -6,7 +6,7 @@ use hir::{
     intravisit::{self, Visitor},
     Body, Expr, ExprKind, Guard, HirId, LoopIdError,
 };
-use rustc_data_structures::fx::FxHashMap;
+use rustc_data_structures::{fx::FxHashMap, stable_set::FxHashSet};
 use rustc_hir as hir;
 use rustc_index::vec::IndexVec;
 use rustc_middle::{
@@ -27,14 +27,14 @@ pub(super) fn build_control_flow_graph<'tcx>(
     consumed_borrowed_places: ConsumedAndBorrowedPlaces,
     body: &'tcx Body<'tcx>,
     num_exprs: usize,
-) -> DropRangesBuilder {
+) -> (DropRangesBuilder, FxHashSet<HirId>) {
     let mut drop_range_visitor =
         DropRangeVisitor::new(hir, tcx, typeck_results, consumed_borrowed_places, num_exprs);
     intravisit::walk_body(&mut drop_range_visitor, body);
 
     drop_range_visitor.drop_ranges.process_deferred_edges();
 
-    drop_range_visitor.drop_ranges
+    (drop_range_visitor.drop_ranges, drop_range_visitor.places.borrowed_temporaries)
 }
 
 /// This struct is used to gather the information for `DropRanges` to determine the regions of the

compiler/rustc_typeck/src/check/generator_interior/drop_ranges/record_consumed_borrow.rs

@@ -6,6 +6,7 @@ use crate::{
 use hir::{def_id::DefId, Body, HirId, HirIdMap};
 use rustc_data_structures::stable_set::FxHashSet;
 use rustc_hir as hir;
+use rustc_middle::hir::place::PlaceBase;
 use rustc_middle::ty::{ParamEnv, TyCtxt};
 
 pub(super) fn find_consumed_and_borrowed<'a, 'tcx>(
@@ -27,8 +28,12 @@ pub(super) struct ConsumedAndBorrowedPlaces {
     /// Note that this set excludes "partial drops" -- for example, a statement like `drop(x.y)` is
     /// not considered a drop of `x`, although it would be a drop of `x.y`.
     pub(super) consumed: HirIdMap<FxHashSet<TrackedValue>>,
+
     /// A set of hir-ids of values or variables that are borrowed at some point within the body.
     pub(super) borrowed: FxHashSet<TrackedValue>,
+
+    /// A set of hir-ids of values or variables that are borrowed at some point within the body.
+    pub(super) borrowed_temporaries: FxHashSet<HirId>,
 }
 
 /// Works with ExprUseVisitor to find interesting values for the drop range analysis.
@@ -49,6 +54,7 @@ impl<'tcx> ExprUseDelegate<'tcx> {
             places: ConsumedAndBorrowedPlaces {
                 consumed: <_>::default(),
                 borrowed: <_>::default(),
+                borrowed_temporaries: <_>::default(),
             },
         }
     }
@@ -98,10 +104,19 @@ impl<'tcx> expr_use_visitor::Delegate<'tcx> for ExprUseDelegate<'tcx> {
         diag_expr_id: HirId,
         _bk: rustc_middle::ty::BorrowKind,
     ) {
-        debug!("borrow {:?}; diag_expr_id={:?}", place_with_id, diag_expr_id);
+        debug!("borrow: place_with_id = {place_with_id:?}, diag_expr_id={diag_expr_id:?}");
+
         self.places
             .borrowed
             .insert(TrackedValue::from_place_with_projections_allowed(place_with_id));
+
+        // XXX -- we need to distinguish "consuming a copy" from other borrows
+        //
+        // XXX -- we need to distinguish `&*E` where `E: &T` which is not creating a temporary
+        // even though the place-base E is an rvalue
+        if let PlaceBase::Rvalue = place_with_id.place.base {
+            self.places.borrowed_temporaries.insert(place_with_id.hir_id);
+        }
     }
 
     fn mutate(

foo.rs

@@ -0,0 +1,21 @@
+// check-pass
+#![feature(generators, negative_impls)]
+
+struct Client;
+
+impl !Sync for Client {}
+
+fn status(_client_status: &Client) -> i16 {
+    200
+}
+
+fn assert_send<T: Send>(_thing: T) {}
+
+// This is the same bug as issue 57017, but using yield instead of await
+fn main() {
+    let client = Client;
+    let g = move || match status(&client) {
+        _status => yield,
+    };
+    assert_send(g);
+}