From a21d2027e1cba01c3d46bf020b7b1411f6e9d3e4 Mon Sep 17 00:00:00 2001
From: Lucian Popescu <lucian.popescu@tecnico.ulisboa.pt>
Date: Sat, 19 Sep 2026 21:00:38 +0100
Subject: [PATCH] Ignore explicit casts to reference types

---
 cpp2rust/converter/converter.cpp        |  5 +++
 tests/unit/out/refcount/refs_as_args.rs | 57 +++++++++++++++++++++++++
 tests/unit/out/unsafe/refs_as_args.rs   | 30 +++++++++++++
 tests/unit/refs_as_args.cpp             | 12 ++++++
 4 files changed, 104 insertions(+)

diff --git a/cpp2rust/converter/converter.cpp b/cpp2rust/converter/converter.cpp
index cf33029e6..b7cb0d64c 100644
--- a/cpp2rust/converter/converter.cpp
+++ b/cpp2rust/converter/converter.cpp
@@ -2520,6 +2520,11 @@ bool Converter::VisitExplicitCastExpr(clang::ExplicitCastExpr *expr) {
     Convert(expr->getSubExpr());
     return false;
   }
+  // A cast to a reference type only rebinds the operand, it converts nothing
+  if (type->isReferenceType()) {
+    Convert(sub_expr);
+    return false;
+  }
   switch (expr->getStmtClass()) {
   case clang::Stmt::CXXReinterpretCastExprClass:
   case clang::Stmt::CXXStaticCastExprClass:
diff --git a/tests/unit/out/refcount/refs_as_args.rs b/tests/unit/out/refcount/refs_as_args.rs
index 1e2b439a8..43edc9a44 100644
--- a/tests/unit/out/refcount/refs_as_args.rs
+++ b/tests/unit/out/refcount/refs_as_args.rs
@@ -42,6 +42,37 @@ pub fn more_refs_0(x1: i32, x2: i32, r1: Ptr<i32>, r2: Ptr<i32>) {
     let __rhs = (rx2.read());
     r1.write(__rhs);
 }
+#[derive(Default)]
+pub struct Val {
+    pub x: Value<i32>,
+}
+impl Clone for Val {
+    fn clone(&self) -> Self {
+        let __this: Value<Val> = Rc::new(RefCell::new(Self {
+            x: Rc::new(RefCell::new((*self.x.borrow()))),
+        }));
+        let this: Ptr<Val> = __this.as_pointer();
+        Rc::try_unwrap(__this).ok().unwrap().into_inner()
+    }
+}
+impl ByteRepr for Val {
+    fn byte_size() -> usize {
+        4
+    }
+    fn to_bytes(&self, buf: &mut [u8]) {
+        (*self.x.borrow()).to_bytes(&mut buf[0..4]);
+    }
+    fn from_bytes(buf: &[u8]) -> Self {
+        Self {
+            x: Rc::new(RefCell::new(<i32>::from_bytes(&buf[0..4]))),
+        }
+    }
+}
+pub fn sum_1(a: Val, b: Val) -> i32 {
+    let a: Value<Val> = Rc::new(RefCell::new(a));
+    let b: Value<Val> = Rc::new(RefCell::new(b));
+    return ((*(*a.borrow()).x.borrow()) + (*(*b.borrow()).x.borrow()));
+}
 pub fn main() {
     __cpp2rust_init_globals();
     std::process::exit(main_0());
@@ -51,6 +82,32 @@ fn main_0() -> i32 {
     let x2: Value<i32> = Rc::new(RefCell::new(2));
     ({ more_refs_0(3, 4, x1.as_pointer(), x2.as_pointer()) });
     assert!((((*x1.borrow()) + (*x2.borrow())) == 21));
+    let v: Value<Val> = Rc::new(RefCell::new(Val {
+        x: Rc::new(RefCell::new(5)),
+    }));
+    let acc: Value<i32> = Rc::new(RefCell::new(
+        ({
+            let _a: Val = (*v.borrow()).clone();
+            let _b: Val = (*v.borrow()).clone();
+            sum_1(_a, _b)
+        }),
+    ));
+    (*acc.borrow_mut()) += ({
+        let _a: Val = (*v.borrow()).clone();
+        let _b: Val = (*v.borrow()).clone();
+        sum_1(_a, _b)
+    });
+    (*acc.borrow_mut()) += ({
+        let _a: Val = (*v.borrow()).clone();
+        let _b: Val = (*v.borrow()).clone();
+        sum_1(_a, _b)
+    });
+    (*acc.borrow_mut()) += ({
+        let _a: Val = (*v.borrow()).clone();
+        let _b: Val = (*v.borrow()).clone();
+        sum_1(_a, _b)
+    });
+    assert!(((*acc.borrow()) == 40));
     return 0;
 }
 pub fn __cpp2rust_init_globals() {}
diff --git a/tests/unit/out/unsafe/refs_as_args.rs b/tests/unit/out/unsafe/refs_as_args.rs
index d75586040..0d6d91a1a 100644
--- a/tests/unit/out/unsafe/refs_as_args.rs
+++ b/tests/unit/out/unsafe/refs_as_args.rs
@@ -17,6 +17,14 @@ pub unsafe fn more_refs_0(mut x1: i32, mut x2: i32, r1: *mut i32, r2: *const i32
     (*rx2) += ((((((((1) + (*rx1)) + (*rx2)) + (*pr1)) + (*pr2)) + (*rpr1)) + (*rpr2)) + (*r));
     (*r1) = (*rx2);
 }
+#[repr(C)]
+#[derive(Copy, Clone, Default)]
+pub struct Val {
+    pub x: i32,
+}
+pub unsafe fn sum_1(mut a: Val, mut b: Val) -> i32 {
+    return ((a.x) + (b.x));
+}
 pub fn main() {
     unsafe {
         __cpp2rust_init_globals();
@@ -28,6 +36,28 @@ unsafe fn main_0() -> i32 {
     let x2: i32 = 2;
     (unsafe { more_refs_0(3, 4, &mut x1, &x2) });
     assert!((((x1) + (x2)) == (21)));
+    let mut v: Val = Val { x: 5 };
+    let mut acc: i32 = (unsafe {
+        let _a: Val = v;
+        let _b: Val = v;
+        sum_1(_a, _b)
+    });
+    acc += (unsafe {
+        let _a: Val = v;
+        let _b: Val = v;
+        sum_1(_a, _b)
+    });
+    acc += (unsafe {
+        let _a: Val = v;
+        let _b: Val = v;
+        sum_1(_a, _b)
+    });
+    acc += (unsafe {
+        let _a: Val = v;
+        let _b: Val = v;
+        sum_1(_a, _b)
+    });
+    assert!(((acc) == (40)));
     return 0;
 }
 pub unsafe fn __cpp2rust_init_globals() {}
diff --git a/tests/unit/refs_as_args.cpp b/tests/unit/refs_as_args.cpp
index 065a279b1..b6afd4205 100644
--- a/tests/unit/refs_as_args.cpp
+++ b/tests/unit/refs_as_args.cpp
@@ -12,10 +12,22 @@ void more_refs(int x1, int x2, int &r1, const int &r2) {
   r1 = rx2;
 }
 
+struct Val {
+  int x;
+};
+
+static int sum(Val a, Val b) { return a.x + b.x; }
+
 int main() {
   int x1 = 1;
   const int x2 = 2;
   more_refs(3, 4, x1, x2);
   assert(x1 + x2 == 21);
+  Val v{5};
+  int acc = sum(static_cast<Val &>(v), v);
+  acc += sum(static_cast<const Val &>(v), v);
+  acc += sum(static_cast<Val &&>(v), v);
+  acc += sum((const Val &)v, v);
+  assert(acc == 40);
   return 0;
 }