From b4738a6b572c0aa3752a6a9bf6c4036de7feee19 Mon Sep 17 00:00:00 2001
From: Samuel Moelius <sam@moeli.us>
Date: Sat, 8 Jul 2023 19:11:15 -0400
Subject: [PATCH 1/2] Add test for #10535

---
 tests/ui/needless_borrow.fixed | 12 ++++++++++++
 tests/ui/needless_borrow.rs    | 12 ++++++++++++
 2 files changed, 24 insertions(+)

diff --git a/tests/ui/needless_borrow.fixed b/tests/ui/needless_borrow.fixed
index 80cdb4e47..1dfbee150 100644
--- a/tests/ui/needless_borrow.fixed
+++ b/tests/ui/needless_borrow.fixed
@@ -492,3 +492,15 @@ mod issue_9782_method_variant {
         S.foo::<&[u8; 100]>(&a);
     }
 }
+
+mod issue_10535 {
+    static SOME_STATIC: String = String::new();
+
+    static UNIT: () = compute(&SOME_STATIC);
+
+    pub const fn compute<T>(_: T)
+    where
+        T: Copy,
+    {
+    }
+}
diff --git a/tests/ui/needless_borrow.rs b/tests/ui/needless_borrow.rs
index 99f735127..3c0d73f5f 100644
--- a/tests/ui/needless_borrow.rs
+++ b/tests/ui/needless_borrow.rs
@@ -492,3 +492,15 @@ mod issue_9782_method_variant {
         S.foo::<&[u8; 100]>(&a);
     }
 }
+
+mod issue_10535 {
+    static SOME_STATIC: String = String::new();
+
+    static UNIT: () = compute(&SOME_STATIC);
+
+    pub const fn compute<T>(_: T)
+    where
+        T: Copy,
+    {
+    }
+}

From 3bf2138289151bb400b53a9817d6e6ab2cf12f13 Mon Sep 17 00:00:00 2001
From: Samuel Moelius <sam@moeli.us>
Date: Sat, 8 Jul 2023 19:12:10 -0400
Subject: [PATCH 2/2] Fix #10535

---
 clippy_lints/src/dereference.rs |  4 ++--
 clippy_utils/src/mir/mod.rs     | 23 ++++++++++++++---------
 2 files changed, 16 insertions(+), 11 deletions(-)

diff --git a/clippy_lints/src/dereference.rs b/clippy_lints/src/dereference.rs
index 73556c105..12f2f37e3 100644
--- a/clippy_lints/src/dereference.rs
+++ b/clippy_lints/src/dereference.rs
@@ -1296,8 +1296,8 @@ fn referent_used_exactly_once<'tcx>(
     possible_borrowers: &mut Vec<(LocalDefId, PossibleBorrowerMap<'tcx, 'tcx>)>,
     reference: &Expr<'tcx>,
 ) -> bool {
-    let mir = enclosing_mir(cx.tcx, reference.hir_id);
-    if let Some(local) = expr_local(cx.tcx, reference)
+    if let Some(mir) = enclosing_mir(cx.tcx, reference.hir_id)
+        && let Some(local) = expr_local(cx.tcx, reference)
         && let [location] = *local_assignments(mir, local).as_slice()
         && let Some(statement) = mir.basic_blocks[location.block].statements.get(location.statement_index)
         && let StatementKind::Assign(box (_, Rvalue::Ref(_, _, place))) = statement.kind
diff --git a/clippy_utils/src/mir/mod.rs b/clippy_utils/src/mir/mod.rs
index 26c0015e8..131f3c0aa 100644
--- a/clippy_utils/src/mir/mod.rs
+++ b/clippy_utils/src/mir/mod.rs
@@ -101,21 +101,26 @@ pub fn used_exactly_once(mir: &rustc_middle::mir::Body<'_>, local: rustc_middle:
 
 /// Returns the `mir::Body` containing the node associated with `hir_id`.
 #[allow(clippy::module_name_repetitions)]
-pub fn enclosing_mir(tcx: TyCtxt<'_>, hir_id: HirId) -> &Body<'_> {
+pub fn enclosing_mir(tcx: TyCtxt<'_>, hir_id: HirId) -> Option<&Body<'_>> {
     let body_owner_local_def_id = tcx.hir().enclosing_body_owner(hir_id);
-    tcx.optimized_mir(body_owner_local_def_id.to_def_id())
+    if tcx.hir().body_owner_kind(body_owner_local_def_id).is_fn_or_closure() {
+        Some(tcx.optimized_mir(body_owner_local_def_id.to_def_id()))
+    } else {
+        None
+    }
 }
 
 /// Tries to determine the `Local` corresponding to `expr`, if any.
 /// This function is expensive and should be used sparingly.
 pub fn expr_local(tcx: TyCtxt<'_>, expr: &Expr<'_>) -> Option<Local> {
-    let mir = enclosing_mir(tcx, expr.hir_id);
-    mir.local_decls.iter_enumerated().find_map(|(local, local_decl)| {
-        if local_decl.source_info.span == expr.span {
-            Some(local)
-        } else {
-            None
-        }
+    enclosing_mir(tcx, expr.hir_id).and_then(|mir| {
+        mir.local_decls.iter_enumerated().find_map(|(local, local_decl)| {
+            if local_decl.source_info.span == expr.span {
+                Some(local)
+            } else {
+                None
+            }
+        })
     })
 }