Reenable generator drop tracking tests and fix mutation handling

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

@@ -6,14 +6,14 @@ 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::map::Map;
+use rustc_middle::ty::{ParamEnv, TyCtxt};
 
 pub(super) fn find_consumed_and_borrowed<'a, 'tcx>(
     fcx: &'a FnCtxt<'a, 'tcx>,
     def_id: DefId,
     body: &'tcx Body<'tcx>,
 ) -> ConsumedAndBorrowedPlaces {
-    let mut expr_use_visitor = ExprUseDelegate::new(fcx.tcx.hir());
+    let mut expr_use_visitor = ExprUseDelegate::new(fcx.tcx, fcx.param_env);
     expr_use_visitor.consume_body(fcx, def_id, body);
     expr_use_visitor.places
 }
@@ -36,14 +36,16 @@ pub(super) struct ConsumedAndBorrowedPlaces {
 /// Interesting values are those that are either dropped or borrowed. For dropped values, we also
 /// record the parent expression, which is the point where the drop actually takes place.
 struct ExprUseDelegate<'tcx> {
-    hir: Map<'tcx>,
+    tcx: TyCtxt<'tcx>,
+    param_env: ParamEnv<'tcx>,
     places: ConsumedAndBorrowedPlaces,
 }
 
 impl<'tcx> ExprUseDelegate<'tcx> {
-    fn new(hir: Map<'tcx>) -> Self {
+    fn new(tcx: TyCtxt<'tcx>, param_env: ParamEnv<'tcx>) -> Self {
         Self {
-            hir,
+            tcx,
+            param_env,
             places: ConsumedAndBorrowedPlaces {
                 consumed: <_>::default(),
                 borrowed: <_>::default(),
@@ -77,7 +79,7 @@ impl<'tcx> expr_use_visitor::Delegate<'tcx> for ExprUseDelegate<'tcx> {
         place_with_id: &expr_use_visitor::PlaceWithHirId<'tcx>,
         diag_expr_id: HirId,
     ) {
-        let parent = match self.hir.find_parent_node(place_with_id.hir_id) {
+        let parent = match self.tcx.hir().find_parent_node(place_with_id.hir_id) {
             Some(parent) => parent,
             None => place_with_id.hir_id,
         };
@@ -107,11 +109,22 @@ impl<'tcx> expr_use_visitor::Delegate<'tcx> for ExprUseDelegate<'tcx> {
         assignee_place: &expr_use_visitor::PlaceWithHirId<'tcx>,
         diag_expr_id: HirId,
     ) {
-        debug!("mutate {:?}; diag_expr_id={:?}", assignee_place, diag_expr_id);
-        // Count mutations as a borrow.
-        self.places
-            .borrowed
-            .insert(TrackedValue::from_place_with_projections_allowed(assignee_place));
+        debug!("mutate {assignee_place:?}; diag_expr_id={diag_expr_id:?}");
+        // If the type being assigned needs dropped, then the mutation counts as a borrow
+        // since it is essentially doing `Drop::drop(&mut x); x = new_value;`.
+        if assignee_place.place.base_ty.needs_drop(self.tcx, self.param_env) {
+            self.places
+                .borrowed
+                .insert(TrackedValue::from_place_with_projections_allowed(assignee_place));
+        }
+    }
+
+    fn bind(
+        &mut self,
+        binding_place: &expr_use_visitor::PlaceWithHirId<'tcx>,
+        diag_expr_id: HirId,
+    ) {
+        debug!("bind {binding_place:?}; diag_expr_id={diag_expr_id:?}");
     }
 
     fn fake_read(

compiler/rustc_typeck/src/expr_use_visitor.rs

@@ -51,6 +51,15 @@ pub trait Delegate<'tcx> {
     /// `diag_expr_id` is the id used for diagnostics (see `consume` for more details).
     fn mutate(&mut self, assignee_place: &PlaceWithHirId<'tcx>, diag_expr_id: hir::HirId);
 
+    /// The path at `binding_place` is a binding that is being initialized.
+    ///
+    /// This covers cases such as `let x = 42;`
+    fn bind(&mut self, binding_place: &PlaceWithHirId<'tcx>, diag_expr_id: hir::HirId) {
+        // Bindings can normally be treated as a regular assignment, so by default we
+        // forward this to the mutate callback.
+        self.mutate(binding_place, diag_expr_id)
+    }
+
     /// The `place` should be a fake read because of specified `cause`.
     fn fake_read(&mut self, place: Place<'tcx>, cause: FakeReadCause, diag_expr_id: hir::HirId);
 }
@@ -648,11 +657,9 @@ impl<'a, 'tcx> ExprUseVisitor<'a, 'tcx> {
                     let pat_ty = return_if_err!(mc.node_ty(pat.hir_id));
                     debug!("walk_pat: pat_ty={:?}", pat_ty);
 
-                    // Each match binding is effectively an assignment to the
-                    // binding being produced.
                     let def = Res::Local(canonical_id);
                     if let Ok(ref binding_place) = mc.cat_res(pat.hir_id, pat.span, pat_ty, def) {
-                        delegate.mutate(binding_place, binding_place.hir_id);
+                        delegate.bind(binding_place, binding_place.hir_id);
                     }
 
                     // It is also a borrow or copy/move of the value being matched.

src/test/ui/async-await/async-fn-nonsend.rs

@@ -1,9 +1,5 @@
 // edition:2018
-// compile-flags: --crate-type lib
-
-// FIXME(eholk): temporarily disabled while drop range tracking is disabled
-// (see generator_interior.rs:27)
-// ignore-test
+// compile-flags: --crate-type lib -Zdrop-tracking
 
 use std::{cell::RefCell, fmt::Debug, rc::Rc};
 

src/test/ui/async-await/drop-and-assign.rs

@@ -0,0 +1,19 @@
+// edition:2021
+// compile-flags: -Zdrop-tracking
+// build-pass
+
+struct A;
+impl Drop for A { fn drop(&mut self) {} }
+
+pub async fn f() {
+    let mut a = A;
+    a = A;
+    drop(a);
+    async {}.await;
+}
+
+fn assert_send<T: Send>(_: T) {}
+
+fn main() {
+    let _ = f();
+}

src/test/ui/async-await/unresolved_type_param.rs

@@ -2,10 +2,7 @@
 // Error message should pinpoint the type parameter T as needing to be bound
 // (rather than give a general error message)
 // edition:2018
-
-// FIXME(eholk): temporarily disabled while drop range tracking is disabled
-// (see generator_interior.rs:27)
-// ignore-test
+// compile-flags: -Zdrop-tracking
 
 async fn bar<T>() -> () {}
 

src/test/ui/async-await/unresolved_type_param.stderr

@@ -1,35 +1,35 @@
 error[E0698]: type inside `async fn` body must be known in this context
-  --> $DIR/unresolved_type_param.rs:9:5
+  --> $DIR/unresolved_type_param.rs:10:5
    |
 LL |     bar().await;
    |     ^^^ cannot infer type for type parameter `T` declared on the function `bar`
    |
 note: the type is part of the `async fn` body because of this `await`
-  --> $DIR/unresolved_type_param.rs:9:10
+  --> $DIR/unresolved_type_param.rs:10:10
    |
 LL |     bar().await;
    |          ^^^^^^
 
 error[E0698]: type inside `async fn` body must be known in this context
-  --> $DIR/unresolved_type_param.rs:9:5
+  --> $DIR/unresolved_type_param.rs:10:5
    |
 LL |     bar().await;
    |     ^^^ cannot infer type for type parameter `T` declared on the function `bar`
    |
 note: the type is part of the `async fn` body because of this `await`
-  --> $DIR/unresolved_type_param.rs:9:10
+  --> $DIR/unresolved_type_param.rs:10:10
    |
 LL |     bar().await;
    |          ^^^^^^
 
 error[E0698]: type inside `async fn` body must be known in this context
-  --> $DIR/unresolved_type_param.rs:9:5
+  --> $DIR/unresolved_type_param.rs:10:5
    |
 LL |     bar().await;
    |     ^^^ cannot infer type for type parameter `T` declared on the function `bar`
    |
 note: the type is part of the `async fn` body because of this `await`
-  --> $DIR/unresolved_type_param.rs:9:10
+  --> $DIR/unresolved_type_param.rs:10:10
    |
 LL |     bar().await;
    |          ^^^^^^

src/test/ui/generator/drop-control-flow.rs

@@ -1,10 +1,6 @@
 // build-pass
 // compile-flags: -Zdrop-tracking
 
-// FIXME(eholk): temporarily disabled while drop range tracking is disabled
-// (see generator_interior.rs:27)
-// ignore-test
-
 // A test to ensure generators capture values that were conditionally dropped,
 // and also that values that are dropped along all paths to a yield do not get
 // included in the generator type.

src/test/ui/generator/issue-57478.rs

@@ -1,8 +1,5 @@
 // check-pass
-
-// FIXME(eholk): temporarily disabled while drop range tracking is disabled
-// (see generator_interior.rs:27)
-// ignore-test
+// compile-flags: -Zdrop-tracking
 
 #![feature(negative_impls, generators)]
 

src/test/ui/generator/partial-drop.rs

@@ -1,6 +1,4 @@
-// FIXME(eholk): temporarily disabled while drop range tracking is disabled
-// (see generator_interior.rs:27)
-// ignore-test
+// compile-flags: -Zdrop-tracking
 
 #![feature(negative_impls, generators)]
 

src/test/ui/generator/partial-drop.stderr

@@ -1,12 +1,12 @@
 error: generator cannot be sent between threads safely
-  --> $DIR/partial-drop.rs:12:5
+  --> $DIR/partial-drop.rs:14:5
    |
 LL |     assert_send(|| {
    |     ^^^^^^^^^^^ generator is not `Send`
    |
-   = help: within `[generator@$DIR/partial-drop.rs:12:17: 18:6]`, the trait `Send` is not implemented for `Foo`
+   = help: within `[generator@$DIR/partial-drop.rs:14:17: 20:6]`, the trait `Send` is not implemented for `Foo`
 note: generator is not `Send` as this value is used across a yield
-  --> $DIR/partial-drop.rs:17:9
+  --> $DIR/partial-drop.rs:19:9
    |
 LL |         let guard = Bar { foo: Foo, x: 42 };
    |             ----- has type `Bar` which is not `Send`
@@ -16,20 +16,20 @@ LL |         yield;
 LL |     });
    |     - `guard` is later dropped here
 note: required by a bound in `assert_send`
-  --> $DIR/partial-drop.rs:40:19
+  --> $DIR/partial-drop.rs:42:19
    |
 LL | fn assert_send<T: Send>(_: T) {}
    |                   ^^^^ required by this bound in `assert_send`
 
 error: generator cannot be sent between threads safely
-  --> $DIR/partial-drop.rs:20:5
+  --> $DIR/partial-drop.rs:22:5
    |
 LL |     assert_send(|| {
    |     ^^^^^^^^^^^ generator is not `Send`
    |
-   = help: within `[generator@$DIR/partial-drop.rs:20:17: 28:6]`, the trait `Send` is not implemented for `Foo`
+   = help: within `[generator@$DIR/partial-drop.rs:22:17: 30:6]`, the trait `Send` is not implemented for `Foo`
 note: generator is not `Send` as this value is used across a yield
-  --> $DIR/partial-drop.rs:27:9
+  --> $DIR/partial-drop.rs:29:9
    |
 LL |         let guard = Bar { foo: Foo, x: 42 };
    |             ----- has type `Bar` which is not `Send`
@@ -39,20 +39,20 @@ LL |         yield;
 LL |     });
    |     - `guard` is later dropped here
 note: required by a bound in `assert_send`
-  --> $DIR/partial-drop.rs:40:19
+  --> $DIR/partial-drop.rs:42:19
    |
 LL | fn assert_send<T: Send>(_: T) {}
    |                   ^^^^ required by this bound in `assert_send`
 
 error: generator cannot be sent between threads safely
-  --> $DIR/partial-drop.rs:30:5
+  --> $DIR/partial-drop.rs:32:5
    |
 LL |     assert_send(|| {
    |     ^^^^^^^^^^^ generator is not `Send`
    |
-   = help: within `[generator@$DIR/partial-drop.rs:30:17: 37:6]`, the trait `Send` is not implemented for `Foo`
+   = help: within `[generator@$DIR/partial-drop.rs:32:17: 39:6]`, the trait `Send` is not implemented for `Foo`
 note: generator is not `Send` as this value is used across a yield
-  --> $DIR/partial-drop.rs:36:9
+  --> $DIR/partial-drop.rs:38:9
    |
 LL |         let guard = Bar { foo: Foo, x: 42 };
    |             ----- has type `Bar` which is not `Send`
@@ -62,7 +62,7 @@ LL |         yield;
 LL |     });
    |     - `guard` is later dropped here
 note: required by a bound in `assert_send`
-  --> $DIR/partial-drop.rs:40:19
+  --> $DIR/partial-drop.rs:42:19
    |
 LL | fn assert_send<T: Send>(_: T) {}
    |                   ^^^^ required by this bound in `assert_send`