From 1702c000562b914e926e4b586f1fb4a6945ab345 Mon Sep 17 00:00:00 2001
From: Santiago Pastorino <spastorino@gmail.com>
Date: Fri, 21 Feb 2025 18:27:58 -0300
Subject: [PATCH] Make captures in ByUse context be always
 ty::UpvarCapture::ByUse

---
 .../rustc_hir_typeck/src/expr_use_visitor.rs  | 27 ++++++++++++-------
 compiler/rustc_hir_typeck/src/upvar.rs        | 23 +++++++++++-----
 2 files changed, 33 insertions(+), 17 deletions(-)

diff --git a/compiler/rustc_hir_typeck/src/expr_use_visitor.rs b/compiler/rustc_hir_typeck/src/expr_use_visitor.rs
index 4b6174769ea6..e7e648dc26b0 100644
--- a/compiler/rustc_hir_typeck/src/expr_use_visitor.rs
+++ b/compiler/rustc_hir_typeck/src/expr_use_visitor.rs
@@ -324,6 +324,18 @@ impl<'tcx, Cx: TypeInformationCtxt<'tcx>, D: Delegate<'tcx>> ExprUseVisitor<'tcx
         }
     }
 
+    pub fn consume_clone_or_copy(&self, place_with_id: &PlaceWithHirId<'tcx>, diag_expr_id: HirId) {
+        debug!("delegate_consume_or_clone(place_with_id={:?})", place_with_id);
+
+        if self.cx.type_is_copy_modulo_regions(place_with_id.place.ty()) {
+            self.delegate.borrow_mut().copy(place_with_id, diag_expr_id);
+        } else if self.cx.type_is_use_cloned_modulo_regions(place_with_id.place.ty()) {
+            self.delegate.borrow_mut().use_cloned(place_with_id, diag_expr_id);
+        } else {
+            self.delegate.borrow_mut().consume(place_with_id, diag_expr_id);
+        }
+    }
+
     fn consume_exprs(&self, exprs: &[hir::Expr<'_>]) -> Result<(), Cx::Error> {
         for expr in exprs {
             self.consume_expr(expr)?;
@@ -346,15 +358,7 @@ impl<'tcx, Cx: TypeInformationCtxt<'tcx>, D: Delegate<'tcx>> ExprUseVisitor<'tcx
         debug!("consume_or_clone_expr(expr={:?})", expr);
 
         let place_with_id = self.cat_expr(expr)?;
-
-        if self.cx.type_is_copy_modulo_regions(place_with_id.place.ty()) {
-            self.delegate.borrow_mut().copy(&place_with_id, place_with_id.hir_id);
-        } else if self.cx.type_is_use_cloned_modulo_regions(place_with_id.place.ty()) {
-            self.delegate.borrow_mut().use_cloned(&place_with_id, place_with_id.hir_id);
-        } else {
-            self.delegate.borrow_mut().consume(&place_with_id, place_with_id.hir_id);
-        }
-
+        self.consume_clone_or_copy(&place_with_id, place_with_id.hir_id);
         self.walk_expr(expr)?;
         Ok(())
     }
@@ -1132,9 +1136,12 @@ impl<'tcx, Cx: TypeInformationCtxt<'tcx>, D: Delegate<'tcx>> ExprUseVisitor<'tcx
                     );
 
                     match capture_info.capture_kind {
-                        ty::UpvarCapture::ByValue | ty::UpvarCapture::ByUse => {
+                        ty::UpvarCapture::ByValue => {
                             self.consume_or_copy(&place_with_id, place_with_id.hir_id);
                         }
+                        ty::UpvarCapture::ByUse => {
+                            self.consume_clone_or_copy(&place_with_id, place_with_id.hir_id);
+                        }
                         ty::UpvarCapture::ByRef(upvar_borrow) => {
                             self.delegate.borrow_mut().borrow(
                                 &place_with_id,
diff --git a/compiler/rustc_hir_typeck/src/upvar.rs b/compiler/rustc_hir_typeck/src/upvar.rs
index 40a935afbac2..f570d0d8a0d3 100644
--- a/compiler/rustc_hir_typeck/src/upvar.rs
+++ b/compiler/rustc_hir_typeck/src/upvar.rs
@@ -1709,11 +1709,12 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
             // Otherwise you'd get an error in 2021 immediately because you'd be trying to take
             // ownership of the (borrowed) String or else you'd take ownership of b, as in 2018 and
             // before, which is also an error.
-            hir::CaptureBy::Value { .. } | hir::CaptureBy::Use { .. }
-                if !place.deref_tys().any(Ty::is_ref) =>
-            {
+            hir::CaptureBy::Value { .. } if !place.deref_tys().any(Ty::is_ref) => {
                 ty::UpvarCapture::ByValue
             }
+            hir::CaptureBy::Use { .. } if !place.deref_tys().any(Ty::is_ref) => {
+                ty::UpvarCapture::ByUse
+            }
             hir::CaptureBy::Value { .. } | hir::CaptureBy::Use { .. } | hir::CaptureBy::Ref => {
                 ty::UpvarCapture::ByRef(BorrowKind::Immutable)
             }
@@ -2404,10 +2405,18 @@ fn determine_capture_info(
         // We select the CaptureKind which ranks higher based the following priority order:
         // (ByUse | ByValue) > MutBorrow > UniqueImmBorrow > ImmBorrow
         match (capture_info_a.capture_kind, capture_info_b.capture_kind) {
-            (ty::UpvarCapture::ByUse, _) => capture_info_a,
-            (_, ty::UpvarCapture::ByUse) => capture_info_b,
-            (ty::UpvarCapture::ByValue, _) => capture_info_a,
-            (_, ty::UpvarCapture::ByValue) => capture_info_b,
+            (ty::UpvarCapture::ByUse, ty::UpvarCapture::ByValue)
+            | (ty::UpvarCapture::ByValue, ty::UpvarCapture::ByUse) => {
+                bug!("Same capture can't be ByUse and ByValue at the same time")
+            }
+            (ty::UpvarCapture::ByValue, ty::UpvarCapture::ByValue)
+            | (ty::UpvarCapture::ByUse, ty::UpvarCapture::ByUse)
+            | (ty::UpvarCapture::ByValue | ty::UpvarCapture::ByUse, ty::UpvarCapture::ByRef(_)) => {
+                capture_info_a
+            }
+            (ty::UpvarCapture::ByRef(_), ty::UpvarCapture::ByValue | ty::UpvarCapture::ByUse) => {
+                capture_info_b
+            }
             (ty::UpvarCapture::ByRef(ref_a), ty::UpvarCapture::ByRef(ref_b)) => {
                 match (ref_a, ref_b) {
                     // Take LHS: