Convert operand as lvalue in array-to-pointer decay (#404)

Author: lucic71

cpp2rust/converter/converter.cpp

@@ -2457,7 +2457,10 @@ bool Converter::VisitImplicitCastExpr(clang::ImplicitCastExpr *expr) {
     }
     bool dest_pointee_const =
         expr->getType()->getPointeeType().isConstQualified();
-    Convert(sub_expr);
+    {
+      PushExprKind push(*this, ExprKind::LValue);
+      Convert(sub_expr);
+    }
     if (IsStringLiteralExpr(sub_expr)) {
       StrCat(".as_ptr()");
       if (!dest_pointee_const) {

tests/unit/array_reference.cpp

@@ -26,6 +26,14 @@ void fill(int (&a)[3], int v) {
 
 int sum_twice(const int (&a)[3]) { return sum(a) + sum(a); }
 
+int sum_ptr(const int *p) { return p[0] + p[1] + p[2]; }
+
+int sum_decayed(const int (&a)[3]) { return sum_ptr(a); }
+
+void bump_ptr(int *p) { p[0] += 1; }
+
+void bump_decayed(int (&a)[3]) { bump_ptr(a); }
+
 void fill_and_sum(int (&a)[3], int v, int &out) {
   fill(a, v);
   out = sum_twice(a);
@@ -74,6 +82,10 @@ int main() {
   assert(pts[0].x == 11);
   assert(pts[1].y == 14);
   assert(sum_points(pts) == 30);
+  assert(sum_decayed(arr) == sum(arr));
+  bump_decayed(arr);
+  assert(arr[0] == 3);
+
   const char *names[2] = {"ab", "cde"};
   assert(total_len(names) == 5);
   return 0;

tests/unit/out/refcount/array_reference.rs

@@ -52,7 +52,26 @@ pub fn sum_twice_4(a: Ptr<Box<[i32]>>) -> i32 {
     return (({ sum_2(((a).clone() as Ptr<Box<[i32]>>)) })
         + ({ sum_2(((a).clone() as Ptr<Box<[i32]>>)) }));
 }
-pub fn fill_and_sum_5(a: Ptr<Box<[i32]>>, v: i32, out: Ptr<i32>) {
+pub fn sum_ptr_5(p: Ptr<i32>) -> i32 {
+    let p: Value<Ptr<i32>> = Rc::new(RefCell::new(p));
+    return ((((*p.borrow()).offset((0) as isize).read())
+        + ((*p.borrow()).offset((1) as isize).read()))
+        + ((*p.borrow()).offset((2) as isize).read()));
+}
+pub fn sum_decayed_6(a: Ptr<Box<[i32]>>) -> i32 {
+    return ({ sum_ptr_5((a.to_strong().as_pointer() as Ptr<i32>)) });
+}
+pub fn bump_ptr_7(p: Ptr<i32>) {
+    let p: Value<Ptr<i32>> = Rc::new(RefCell::new(p));
+    {
+        let _ptr = (*p.borrow()).offset((0) as isize);
+        _ptr.write(_ptr.read() + 1)
+    };
+}
+pub fn bump_decayed_8(a: Ptr<Box<[i32]>>) {
+    ({ bump_ptr_7((a.to_strong().as_pointer() as Ptr<i32>)) });
+}
+pub fn fill_and_sum_9(a: Ptr<Box<[i32]>>, v: i32, out: Ptr<i32>) {
     let v: Value<i32> = Rc::new(RefCell::new(v));
     ({
         let _a: Ptr<Box<[i32]>> = ((a).clone() as Ptr<Box<[i32]>>);
@@ -62,7 +81,7 @@ pub fn fill_and_sum_5(a: Ptr<Box<[i32]>>, v: i32, out: Ptr<i32>) {
     let __rhs = ({ sum_twice_4(((a).clone() as Ptr<Box<[i32]>>)) });
     out.write(__rhs);
 }
-pub fn pick_6(s: Ptr<Box<[u8]>>) -> Ptr<Box<[u8]>> {
+pub fn pick_10(s: Ptr<Box<[u8]>>) -> Ptr<Box<[u8]>> {
     return ((s).clone() as Ptr<Box<[u8]>>);
 }
 #[derive(Default)]
@@ -95,7 +114,7 @@ impl ByteRepr for Point {
         }
     }
 }
-pub fn sum_points_7(p: Ptr<Box<[Point]>>) -> i32 {
+pub fn sum_points_11(p: Ptr<Box<[Point]>>) -> i32 {
     return {
         let _lhs = {
             let _lhs = {
@@ -127,7 +146,7 @@ pub fn sum_points_7(p: Ptr<Box<[Point]>>) -> i32 {
         .borrow())
     };
 }
-pub fn shift_points_8(p: Ptr<Box<[Point]>>, d: i32) {
+pub fn shift_points_12(p: Ptr<Box<[Point]>>, d: i32) {
     let d: Value<i32> = Rc::new(RefCell::new(d));
     (*(*(p.to_strong().as_pointer() as Ptr<Point>)
         .offset((0) as isize)
@@ -142,7 +161,7 @@ pub fn shift_points_8(p: Ptr<Box<[Point]>>, d: i32) {
     .y
     .borrow_mut()) += (*d.borrow());
 }
-pub fn total_len_9(names: Ptr<Box<[Ptr<u8>]>>) -> i32 {
+pub fn total_len_13(names: Ptr<Box<[Ptr<u8>]>>) -> i32 {
     return (({
         len5_1(
             ((names.to_strong().as_pointer() as Ptr<Ptr<u8>>)
@@ -173,21 +192,21 @@ fn main_0() -> i32 {
     assert!((({ sum_2((arr.as_pointer() as Ptr<Box<[i32]>>),) }) == 21));
     assert!((({ sum_twice_4((arr.as_pointer() as Ptr<Box<[i32]>>),) }) == 42));
     let out: Value<i32> = Rc::new(RefCell::new(0));
-    ({ fill_and_sum_5((arr.as_pointer() as Ptr<Box<[i32]>>), 2, out.as_pointer()) });
+    ({ fill_and_sum_9((arr.as_pointer() as Ptr<Box<[i32]>>), 2, out.as_pointer()) });
     assert!(((*out.borrow()) == 12));
     assert!(((*arr.borrow())[(0) as usize] == 2));
     let lit: Ptr<Box<[u8]>> = Ptr::<Box<[u8]>>::from_string_literal_array(b"beta");
     assert!((({ len_0(((lit).clone() as Ptr<Box<[u8]>>),) }) == 4));
     assert!(
-        ((((({ pick_6(Ptr::<Box<[u8]>>::from_string_literal_array(b"beta"),) })
+        ((((({ pick_10(Ptr::<Box<[u8]>>::from_string_literal_array(b"beta"),) })
             .to_strong()
             .as_pointer() as Ptr::<u8>)
             .offset((0) as isize)
             .read()) as i32)
             == (('b' as u8) as i32))
     );
     assert!(
-        (({ len_0((({ pick_6((buf.as_pointer() as Ptr<Box<[u8]>>),) }) as Ptr<Box<[u8]>>),) })
+        (({ len_0((({ pick_10((buf.as_pointer() as Ptr<Box<[u8]>>),) }) as Ptr<Box<[u8]>>),) })
             == 4)
     );
     let pts: Value<Box<[Point]>> = Rc::new(RefCell::new(Box::new([
@@ -200,16 +219,22 @@ fn main_0() -> i32 {
             y: Rc::new(RefCell::new(4)),
         },
     ])));
-    assert!((({ sum_points_7((pts.as_pointer() as Ptr<Box<[Point]>>),) }) == 10));
-    ({ shift_points_8((pts.as_pointer() as Ptr<Box<[Point]>>), 10) });
+    assert!((({ sum_points_11((pts.as_pointer() as Ptr<Box<[Point]>>),) }) == 10));
+    ({ shift_points_12((pts.as_pointer() as Ptr<Box<[Point]>>), 10) });
     assert!(((*(*pts.borrow())[(0) as usize].x.borrow()) == 11));
     assert!(((*(*pts.borrow())[(1) as usize].y.borrow()) == 14));
-    assert!((({ sum_points_7((pts.as_pointer() as Ptr<Box<[Point]>>),) }) == 30));
+    assert!((({ sum_points_11((pts.as_pointer() as Ptr<Box<[Point]>>),) }) == 30));
+    assert!(
+        (({ sum_decayed_6((arr.as_pointer() as Ptr<Box<[i32]>>),) })
+            == ({ sum_2((arr.as_pointer() as Ptr<Box<[i32]>>),) }))
+    );
+    ({ bump_decayed_8((arr.as_pointer() as Ptr<Box<[i32]>>)) });
+    assert!(((*arr.borrow())[(0) as usize] == 3));
     let names: Value<Box<[Ptr<u8>]>> = Rc::new(RefCell::new(Box::new([
         Ptr::<u8>::from_string_literal(b"ab"),
         Ptr::<u8>::from_string_literal(b"cde"),
     ])));
-    assert!((({ total_len_9((names.as_pointer() as Ptr<Box<[Ptr::<u8>]>>),) }) == 5));
+    assert!((({ total_len_13((names.as_pointer() as Ptr<Box<[Ptr::<u8>]>>),) }) == 5));
     return 0;
 }
 pub fn __cpp2rust_init_globals() {}

tests/unit/out/unsafe/array_reference.rs

@@ -33,15 +33,27 @@ pub unsafe fn fill_3(a: *mut [i32; 3], mut v: i32) {
 pub unsafe fn sum_twice_4(a: *const [i32; 3]) -> i32 {
     return ((unsafe { sum_2(a) }) + (unsafe { sum_2(a) }));
 }
-pub unsafe fn fill_and_sum_5(a: *mut [i32; 3], mut v: i32, out: *mut i32) {
+pub unsafe fn sum_ptr_5(mut p: *const i32) -> i32 {
+    return (((*p.offset((0) as isize)) + (*p.offset((1) as isize))) + (*p.offset((2) as isize)));
+}
+pub unsafe fn sum_decayed_6(a: *const [i32; 3]) -> i32 {
+    return (unsafe { sum_ptr_5((*a).as_ptr()) });
+}
+pub unsafe fn bump_ptr_7(mut p: *mut i32) {
+    (*p.offset((0) as isize)) += 1;
+}
+pub unsafe fn bump_decayed_8(a: *mut [i32; 3]) {
+    (unsafe { bump_ptr_7((*a).as_mut_ptr()) });
+}
+pub unsafe fn fill_and_sum_9(a: *mut [i32; 3], mut v: i32, out: *mut i32) {
     (unsafe {
         let _a: *mut [i32; 3] = a;
         let _v: i32 = v;
         fill_3(_a, _v)
     });
     (*out) = (unsafe { sum_twice_4(a) });
 }
-pub unsafe fn pick_6(s: *const [libc::c_char; 5]) -> *const [libc::c_char; 5] {
+pub unsafe fn pick_10(s: *const [libc::c_char; 5]) -> *const [libc::c_char; 5] {
     return s;
 }
 #[repr(C)]
@@ -50,15 +62,15 @@ pub struct Point {
     pub x: i32,
     pub y: i32,
 }
-pub unsafe fn sum_points_7(p: *const [Point; 2]) -> i32 {
+pub unsafe fn sum_points_11(p: *const [Point; 2]) -> i32 {
     return (((((*p)[(0) as usize].x) + ((*p)[(0) as usize].y)) + ((*p)[(1) as usize].x))
         + ((*p)[(1) as usize].y));
 }
-pub unsafe fn shift_points_8(p: *mut [Point; 2], mut d: i32) {
+pub unsafe fn shift_points_12(p: *mut [Point; 2], mut d: i32) {
     (*p)[(0) as usize].x += d;
     (*p)[(1) as usize].y += d;
 }
-pub unsafe fn total_len_9(names: *mut [*const libc::c_char; 2]) -> i32 {
+pub unsafe fn total_len_13(names: *mut [*const libc::c_char; 2]) -> i32 {
     return ((unsafe { len5_1((*names)[(0) as usize]) })
         + (unsafe { len5_1((*names)[(1) as usize]) }));
 }
@@ -78,24 +90,27 @@ unsafe fn main_0() -> i32 {
     assert!(((unsafe { sum_2(&arr,) }) == (21)));
     assert!(((unsafe { sum_twice_4(&arr,) }) == (42)));
     let mut out: i32 = 0;
-    (unsafe { fill_and_sum_5(&mut arr, 2, &mut out) });
+    (unsafe { fill_and_sum_9(&mut arr, 2, &mut out) });
     assert!(((out) == (12)));
     assert!(((arr[(0) as usize]) == (2)));
     let lit: *const [libc::c_char; 5] = &std::mem::transmute(*b"beta\0");
     assert!(((unsafe { len_0(lit,) }) == (4)));
     assert!(
-        (((*(unsafe { pick_6(&std::mem::transmute(*b"beta\0"),) }))[(0) as usize] as i32)
+        (((*(unsafe { pick_10(&std::mem::transmute(*b"beta\0"),) }))[(0) as usize] as i32)
             == (('b' as libc::c_char) as i32))
     );
-    assert!(((unsafe { len_0((unsafe { pick_6(&buf,) }),) }) == (4)));
+    assert!(((unsafe { len_0((unsafe { pick_10(&buf,) }),) }) == (4)));
     let mut pts: [Point; 2] = [Point { x: 1, y: 2 }, Point { x: 3, y: 4 }];
-    assert!(((unsafe { sum_points_7(&pts,) }) == (10)));
-    (unsafe { shift_points_8(&mut pts, 10) });
+    assert!(((unsafe { sum_points_11(&pts,) }) == (10)));
+    (unsafe { shift_points_12(&mut pts, 10) });
     assert!(((pts[(0) as usize].x) == (11)));
     assert!(((pts[(1) as usize].y) == (14)));
-    assert!(((unsafe { sum_points_7(&pts,) }) == (30)));
+    assert!(((unsafe { sum_points_11(&pts,) }) == (30)));
+    assert!(((unsafe { sum_decayed_6(&arr,) }) == (unsafe { sum_2(&arr,) })));
+    (unsafe { bump_decayed_8(&mut arr) });
+    assert!(((arr[(0) as usize]) == (3)));
     let mut names: [*const libc::c_char; 2] = [c"ab".as_ptr(), c"cde".as_ptr()];
-    assert!(((unsafe { total_len_9(&mut names,) }) == (5)));
+    assert!(((unsafe { total_len_13(&mut names,) }) == (5)));
     return 0;
 }
 pub unsafe fn __cpp2rust_init_globals() {}