Translate void casts (#47)

lucic71 · web-flow · commit abea5bfa3ef9 · 2026-05-01T08:08:34.000+01:00
diff --git a/cpp2rust/converter/converter.cpp b/cpp2rust/converter/converter.cpp
@@ -1869,6 +1869,8 @@ bool Converter::VisitExplicitCastExpr(clang::ExplicitCastExpr *expr) {
   auto type = expr->getTypeAsWritten();
   auto *sub_expr = expr->getSubExpr();
   if (type->isVoidType()) {
+    PushExprKind push(*this, ExprKind::Void);
+    Convert(expr->getSubExpr());
     return false;
   }
   switch (expr->getStmtClass()) {
@@ -1950,7 +1952,10 @@ bool Converter::VisitBinaryOperator(clang::BinaryOperator *expr) {
       ConvertCast(lhs_type);
     }
   } else if (expr->isCommaOp()) {
-    Convert(lhs);
+    {
+      PushExprKind push(*this, ExprKind::Void);
+      Convert(lhs);
+    }
     StrCat(token::kSemiColon);
     Convert(rhs);
   } else if (IsUnsignedArithOp(expr)) {
@@ -2248,11 +2253,20 @@ bool Converter::VisitDeclRefExpr(clang::DeclRefExpr *expr) {
 }
 
 bool Converter::VisitParenExpr(clang::ParenExpr *expr) {
+  // Comma operator becomes (A, B, C) -> { A; B; C }
+  if (auto *bin = clang::dyn_cast<clang::BinaryOperator>(expr->getSubExpr())) {
+    if (bin->isCommaOp()) {
+      PushBrace push(*this);
+      Convert(expr->getSubExpr());
+      return false;
+    }
+  }
+
   // Add cast to avoid ambigous integers. Don't add cast if sub expression is a
   // pointer dereference because we might want to mutate the dereferenced value.
   bool should_add_integral_cast =
       expr->getType()->isIntegralOrEnumerationType() && !isAddrOf() &&
-      !clang::isa<clang::UnaryOperator>(expr->getSubExpr());
+      !isVoid() && !clang::isa<clang::UnaryOperator>(expr->getSubExpr());
   PushParen outer(*this, should_add_integral_cast);
 
   {
@@ -3399,7 +3413,7 @@ void Converter::ConvertUnsignedArithBinaryOperator(clang::BinaryOperator *op,
 
 void Converter::ConvertAddrOf(clang::Expr *expr, clang::QualType pointer_type) {
   assert(pointer_type->isPointerType());
-  if (IsReferenceType(expr)) {
+  if (IsReferenceType(expr) || pointer_type->isFunctionPointerType()) {
     PushExprKind push(*this, ExprKind::AddrOf);
     Convert(expr);
   } else {
diff --git a/cpp2rust/converter/converter_lib.cpp b/cpp2rust/converter/converter_lib.cpp
@@ -814,4 +814,9 @@ ConstCastType GetConstCastType(clang::QualType to, clang::QualType from) {
   }
 }
 
+bool TypeIsCopyable(clang::QualType ty) {
+  return ty->isIntegerType() || ty->isFunctionPointerType() ||
+         ty->isFunctionType();
+}
+
 } // namespace cpp2rust
diff --git a/cpp2rust/converter/converter_lib.h b/cpp2rust/converter/converter_lib.h
@@ -180,4 +180,6 @@ enum class ConstCastType {
 
 ConstCastType GetConstCastType(clang::QualType to, clang::QualType from);
 
+bool TypeIsCopyable(clang::QualType ty);
+
 } // namespace cpp2rust
diff --git a/cpp2rust/converter/models/converter_refcount.cpp b/cpp2rust/converter/models/converter_refcount.cpp
@@ -1128,6 +1128,11 @@ bool ConverterRefCount::VisitFunctionPointerCast(
 
 bool ConverterRefCount::VisitExplicitCastExpr(clang::ExplicitCastExpr *expr) {
   if (expr->getTypeAsWritten()->isVoidType()) {
+    PushExprKind push(*this, ExprKind::Void);
+    Convert(expr->getSubExpr());
+    if (!TypeIsCopyable(expr->getSubExpr()->getType())) {
+      StrCat(".clone()");
+    }
     return false;
   }
   switch (expr->getStmtClass()) {
diff --git a/tests/unit/comma_operator.cpp b/tests/unit/comma_operator.cpp
@@ -0,0 +1,24 @@
+#include <cassert>
+
+int main() {
+  int x = 1;
+  int y = (x = 2, x + 1);
+  assert(x == 2);
+  assert(y == 3);
+
+  int z = (1, 2, 3);
+  assert(z == 3);
+
+  int counter = 0;
+  int w = (counter++, counter++, counter);
+  assert(counter == 2);
+  assert(w == 2);
+
+  int a = 0, b = 0;
+  if ((a = 1, b = 2, a + b > 0)) {
+    assert(a == 1);
+    assert(b == 2);
+  }
+
+  return 0;
+}
diff --git a/tests/unit/out/refcount/bool_printing.rs b/tests/unit/out/refcount/bool_printing.rs
@@ -23,12 +23,12 @@ fn main_0() -> i32 {
     write!(
         libcc2rs::cout(),
         "{:}\n",
-        ((((*i1.borrow()) != (*i2.borrow())) as bool) as u8),
+        (((*i1.borrow()) != (*i2.borrow())) as u8),
     );
     write!(
         libcc2rs::cout(),
         "{:}\n",
-        ((((*i1.borrow()) == (*i2.borrow())) as bool) as u8),
+        (((*i1.borrow()) == (*i2.borrow())) as u8),
     );
     write!(libcc2rs::cout(), "{:}\n", (({ foo_0() }) as u8),);
     write!(libcc2rs::cout(), "{:}\n", (({ bar_1() }) as u8),);
diff --git a/tests/unit/out/refcount/comma_operator.rs b/tests/unit/out/refcount/comma_operator.rs
@@ -0,0 +1,45 @@
+extern crate libcc2rs;
+use libcc2rs::*;
+use std::cell::RefCell;
+use std::collections::BTreeMap;
+use std::io::prelude::*;
+use std::io::{Read, Seek, Write};
+use std::os::fd::AsFd;
+use std::rc::{Rc, Weak};
+pub fn main() {
+    std::process::exit(main_0());
+}
+fn main_0() -> i32 {
+    let x: Value<i32> = Rc::new(RefCell::new(1));
+    let y: Value<i32> = Rc::new(RefCell::new({
+        (*x.borrow_mut()) = 2;
+        ((*x.borrow()) + 1)
+    }));
+    assert!(((*x.borrow()) == 2));
+    assert!(((*y.borrow()) == 3));
+    let z: Value<i32> = Rc::new(RefCell::new({
+        1;
+        2;
+        3
+    }));
+    assert!(((*z.borrow()) == 3));
+    let counter: Value<i32> = Rc::new(RefCell::new(0));
+    let w: Value<i32> = Rc::new(RefCell::new({
+        (*counter.borrow_mut()).postfix_inc();
+        (*counter.borrow_mut()).postfix_inc();
+        (*counter.borrow())
+    }));
+    assert!(((*counter.borrow()) == 2));
+    assert!(((*w.borrow()) == 2));
+    let a: Value<i32> = Rc::new(RefCell::new(0));
+    let b: Value<i32> = Rc::new(RefCell::new(0));
+    if {
+        (*a.borrow_mut()) = 1;
+        (*b.borrow_mut()) = 2;
+        (((*a.borrow()) + (*b.borrow())) > 0)
+    } {
+        assert!(((*a.borrow()) == 1));
+        assert!(((*b.borrow()) == 2));
+    }
+    return 0;
+}
diff --git a/tests/unit/out/refcount/continue.rs b/tests/unit/out/refcount/continue.rs
@@ -35,14 +35,14 @@ fn main_0() -> i32 {
         'loop_: while ((*k2.borrow()) < 5) {
             let k3: Value<i32> = Rc::new(RefCell::new(0));
             'loop_: while ((*k3.borrow()) < 5) {
-                if ((((((*k1.borrow()) + (*k2.borrow())) + (*k3.borrow())) as i32) % 2) == 0) {
+                if (((((*k1.borrow()) + (*k2.borrow())) + (*k3.borrow())) % 2) == 0) {
                     (*k3.borrow_mut()).postfix_inc();
                     continue 'loop_;
                 }
                 (*out.borrow_mut()).prefix_inc();
                 (*k3.borrow_mut()).postfix_inc();
             }
-            if (((((*k1.borrow()) + (*k2.borrow())) as i32) % 2) == 0) {
+            if ((((*k1.borrow()) + (*k2.borrow())) % 2) == 0) {
                 (*k2.borrow_mut()).postfix_inc();
                 continue 'loop_;
             }
diff --git a/tests/unit/out/refcount/reinterpret_cast_oob_read.rs b/tests/unit/out/refcount/reinterpret_cast_oob_read.rs
@@ -15,5 +15,6 @@ fn main_0() -> i32 {
     let x: Value<u8> = Rc::new(RefCell::new(
         ((*bytes.borrow()).offset((4) as isize).read()),
     ));
+    (*x.borrow_mut());
     return 0;
 }
diff --git a/tests/unit/out/refcount/reinterpret_cast_undersize.rs b/tests/unit/out/refcount/reinterpret_cast_undersize.rs
@@ -13,5 +13,6 @@ fn main_0() -> i32 {
     let b: Value<u8> = Rc::new(RefCell::new(66_u8));
     let p: Value<Ptr<u32>> = Rc::new(RefCell::new((b.as_pointer()).reinterpret_cast::<u32>()));
     let val: Value<u32> = Rc::new(RefCell::new(((*p.borrow()).read())));
+    (*val.borrow_mut());
     return 0;
 }
diff --git a/tests/unit/out/refcount/string_escape.rs b/tests/unit/out/refcount/string_escape.rs
@@ -23,8 +23,8 @@ fn main_0() -> i32 {
     );
     let i: Value<i32> = Rc::new(RefCell::new(0));
     'loop_: while ((*i.borrow())
-        < ((((::std::mem::size_of::<[u8; 40]>() as u64 as u64)
-            .wrapping_div(::std::mem::size_of::<u8>() as u64 as u64)) as u64) as i32))
+        < (((::std::mem::size_of::<[u8; 40]>() as u64 as u64)
+            .wrapping_div(::std::mem::size_of::<u8>() as u64 as u64)) as i32))
     {
         assert!({
             let _lhs = (((*special.borrow()).offset((*i.borrow()) as isize).read()) as i32);
diff --git a/tests/unit/out/refcount/va_arg_printf.rs b/tests/unit/out/refcount/va_arg_printf.rs
@@ -9,6 +9,7 @@ use std::rc::{Rc, Weak};
 pub fn logf_impl_0(fmt: Ptr<u8>, ap: VaList) -> i32 {
     let fmt: Value<Ptr<u8>> = Rc::new(RefCell::new(fmt));
     let ap: Value<VaList> = Rc::new(RefCell::new(ap));
+    (*fmt.borrow()).clone();
     return {
         let _lhs = ((*ap.borrow_mut()).arg::<i32>()).clone();
         _lhs + ((*ap.borrow_mut()).arg::<i32>()).clone()
diff --git a/tests/unit/out/refcount/void_cast.rs b/tests/unit/out/refcount/void_cast.rs
@@ -0,0 +1,97 @@
+extern crate libcc2rs;
+use libcc2rs::*;
+use std::cell::RefCell;
+use std::collections::BTreeMap;
+use std::io::prelude::*;
+use std::io::{Read, Seek, Write};
+use std::os::fd::AsFd;
+use std::rc::{Rc, Weak};
+pub fn unused_param_0(x: i32) {
+    let x: Value<i32> = Rc::new(RefCell::new(x));
+    (*x.borrow_mut());
+}
+thread_local!(
+    pub static side_effect_counter: Value<i32> = Rc::new(RefCell::new(0));
+);
+pub fn bump_and_return_1() -> i32 {
+    (*side_effect_counter.with(Value::clone).borrow_mut()).prefix_inc();
+    return (*side_effect_counter.with(Value::clone).borrow());
+}
+#[derive(Default)]
+pub struct Holder {
+    pub field: Value<i32>,
+}
+impl Clone for Holder {
+    fn clone(&self) -> Self {
+        let mut this = Self {
+            field: Rc::new(RefCell::new((*self.field.borrow()))),
+        };
+        this
+    }
+}
+impl ByteRepr for Holder {}
+pub fn main() {
+    std::process::exit(main_0());
+}
+fn main_0() -> i32 {
+    ({
+        let _x: i32 = 42;
+        unused_param_0(_x)
+    });
+    let y: Value<i32> = Rc::new(RefCell::new(5));
+    (*y.borrow_mut());
+    let z: Value<i32> = Rc::new(RefCell::new({
+        (*y.borrow_mut());
+        7
+    }));
+    assert!(((*z.borrow()) == 7));
+    let counter: Value<i32> = Rc::new(RefCell::new(0));
+    let w: Value<i32> = Rc::new(RefCell::new({
+        (*counter.borrow_mut());
+        (*counter.borrow_mut()) = 3;
+        (*counter.borrow())
+    }));
+    assert!(((*w.borrow()) == 3));
+    assert!(((*counter.borrow()) == 3));
+    ({ bump_and_return_1() });
+    assert!(((*side_effect_counter.with(Value::clone).borrow()) == 1));
+    let v: Value<i32> = Rc::new(RefCell::new({
+        ({ bump_and_return_1() });
+        99
+    }));
+    assert!(((*side_effect_counter.with(Value::clone).borrow()) == 2));
+    assert!(((*v.borrow()) == 99));
+    0;
+    (0);
+    (*y.borrow_mut());
+    (0);
+    (*y.borrow_mut());
+    let err: Value<i32> = Rc::new(RefCell::new(0));
+    ((*err.borrow_mut()) = 42);
+    assert!(((*err.borrow()) == 42));
+    let chosen: Value<i32> = Rc::new(RefCell::new({
+        ((*err.borrow_mut()) = 7);
+        123
+    }));
+    assert!(((*err.borrow()) == 7));
+    assert!(((*chosen.borrow()) == 123));
+    bump_and_return_1;
+    assert!(((*side_effect_counter.with(Value::clone).borrow()) == 2));
+    (FnPtr::<fn() -> i32>::new(bump_and_return_1));
+    assert!(((*side_effect_counter.with(Value::clone).borrow()) == 2));
+    ((FnPtr::<fn() -> i32>::new(bump_and_return_1)).cast::<fn() -> i32>(None));
+    assert!(((*side_effect_counter.with(Value::clone).borrow()) == 2));
+    let storage: Value<i32> = Rc::new(RefCell::new(11));
+    let p: Value<Ptr<i32>> = Rc::new(RefCell::new((storage.as_pointer())));
+    ((*p.borrow()).read());
+    (*p.borrow_mut()).clone();
+    let arr: Value<Box<[i32]>> = Rc::new(RefCell::new(Box::new([1, 2, 3])));
+    ((*arr.borrow_mut())[(1) as usize]);
+    let h: Value<Holder> = Rc::new(RefCell::new(Holder {
+        field: Rc::new(RefCell::new(17)),
+    }));
+    (*(*h.borrow()).field.borrow_mut());
+    let hp: Value<Ptr<Holder>> = Rc::new(RefCell::new((h.as_pointer())));
+    (*(*(*hp.borrow()).upgrade().deref()).field.borrow_mut());
+    return 0;
+}
diff --git a/tests/unit/out/unsafe/bool_printing.rs b/tests/unit/out/unsafe/bool_printing.rs
@@ -51,7 +51,7 @@ unsafe fn main_0() -> i32 {
                 .into_raw_fd(),
         ),
         "{:}\n",
-        ((((i1) != (i2)) as bool) as u8),
+        (((i1) != (i2)) as u8),
     );
     write!(
         std::fs::File::from_raw_fd(
@@ -62,7 +62,7 @@ unsafe fn main_0() -> i32 {
                 .into_raw_fd(),
         ),
         "{:}\n",
-        ((((i1) == (i2)) as bool) as u8),
+        (((i1) == (i2)) as u8),
     );
     write!(
         std::fs::File::from_raw_fd(
diff --git a/tests/unit/out/unsafe/comma_operator.rs b/tests/unit/out/unsafe/comma_operator.rs
@@ -0,0 +1,47 @@
+extern crate libc;
+use libc::*;
+extern crate libcc2rs;
+use libcc2rs::*;
+use std::collections::BTreeMap;
+use std::io::{Read, Seek, Write};
+use std::os::fd::{AsFd, FromRawFd, IntoRawFd};
+use std::rc::Rc;
+pub fn main() {
+    unsafe {
+        std::process::exit(main_0() as i32);
+    }
+}
+unsafe fn main_0() -> i32 {
+    let mut x: i32 = 1;
+    let mut y: i32 = {
+        x = 2;
+        ((x) + (1))
+    };
+    assert!(((x) == (2)));
+    assert!(((y) == (3)));
+    let mut z: i32 = {
+        1;
+        2;
+        3
+    };
+    assert!(((z) == (3)));
+    let mut counter: i32 = 0;
+    let mut w: i32 = {
+        counter.postfix_inc();
+        counter.postfix_inc();
+        counter
+    };
+    assert!(((counter) == (2)));
+    assert!(((w) == (2)));
+    let mut a: i32 = 0;
+    let mut b: i32 = 0;
+    if {
+        a = 1;
+        b = 2;
+        (((a) + (b)) > (0))
+    } {
+        assert!(((a) == (1)));
+        assert!(((b) == (2)));
+    }
+    return 0;
+}
diff --git a/tests/unit/out/unsafe/continue.rs b/tests/unit/out/unsafe/continue.rs
@@ -37,14 +37,14 @@ unsafe fn main_0() -> i32 {
         'loop_: while ((k2) < (5)) {
             let mut k3: i32 = 0;
             'loop_: while ((k3) < (5)) {
-                if ((((((k1) + (k2)) + (k3)) as i32) % (2)) == (0)) {
+                if (((((k1) + (k2)) + (k3)) % (2)) == (0)) {
                     k3.postfix_inc();
                     continue 'loop_;
                 }
                 out.prefix_inc();
                 k3.postfix_inc();
             }
-            if (((((k1) + (k2)) as i32) % (2)) == (0)) {
+            if ((((k1) + (k2)) % (2)) == (0)) {
                 k2.postfix_inc();
                 continue 'loop_;
             }
diff --git a/tests/unit/out/unsafe/reinterpret_cast_oob_read.rs b/tests/unit/out/unsafe/reinterpret_cast_oob_read.rs
diff --git a/tests/unit/out/unsafe/reinterpret_cast_undersize.rs b/tests/unit/out/unsafe/reinterpret_cast_undersize.rs
diff --git a/tests/unit/out/unsafe/string_escape.rs b/tests/unit/out/unsafe/string_escape.rs
diff --git a/tests/unit/out/unsafe/va_arg_printf.rs b/tests/unit/out/unsafe/va_arg_printf.rs
diff --git a/tests/unit/out/unsafe/void_cast.rs b/tests/unit/out/unsafe/void_cast.rs
diff --git a/tests/unit/void_cast.cpp b/tests/unit/void_cast.cpp

Original file line number	Diff line number	Diff line change
`@@ -814,4 +814,9 @@ ConstCastType GetConstCastType(clang::QualType to, clang::QualType from) {`
`814`	`814`	`}`
`815`	`815`	`}`
`816`	`816`
	`817`	`+bool TypeIsCopyable(clang::QualType ty) {`
	`818`	`+ return ty->isIntegerType() \|\| ty->isFunctionPointerType() \|\|`
	`819`	`+ ty->isFunctionType();`
	`820`	`+}`
	`821`	`+`
`817`	`822`	`} // namespace cpp2rust`
Original file line number	Diff line number	Diff line change
`@@ -35,14 +35,14 @@ fn main_0() -> i32 {`
`35`	`35`	`'loop_: while ((*k2.borrow()) < 5) {`
`36`	`36`	`let k3: Value<i32> = Rc::new(RefCell::new(0));`
`37`	`37`	`'loop_: while ((*k3.borrow()) < 5) {`
`38`		`- if ((((((k1.borrow()) + (k2.borrow())) + (*k3.borrow())) as i32) % 2) == 0) {`
	`38`	`+ if (((((k1.borrow()) + (k2.borrow())) + (*k3.borrow())) % 2) == 0) {`
`39`	`39`	`(*k3.borrow_mut()).postfix_inc();`
`40`	`40`	`continue 'loop_;`
`41`	`41`	`}`
`42`	`42`	`(*out.borrow_mut()).prefix_inc();`
`43`	`43`	`(*k3.borrow_mut()).postfix_inc();`
`44`	`44`	`}`
`45`		`- if (((((k1.borrow()) + (k2.borrow())) as i32) % 2) == 0) {`
	`45`	`+ if ((((k1.borrow()) + (k2.borrow())) % 2) == 0) {`
`46`	`46`	`(*k2.borrow_mut()).postfix_inc();`
`47`	`47`	`continue 'loop_;`
`48`	`48`	`}`
Original file line number	Diff line number	Diff line change
`@@ -15,5 +15,6 @@ fn main_0() -> i32 {`
`15`	`15`	`let x: Value<u8> = Rc::new(RefCell::new(`
`16`	`16`	`((*bytes.borrow()).offset((4) as isize).read()),`
`17`	`17`	`));`
	`18`	`+ (*x.borrow_mut());`
`18`	`19`	`return 0;`
`19`	`20`	`}`
Original file line number	Diff line number	Diff line change
`@@ -13,5 +13,6 @@ fn main_0() -> i32 {`
`13`	`13`	`let b: Value<u8> = Rc::new(RefCell::new(66_u8));`
`14`	`14`	`let p: Value<Ptr<u32>> = Rc::new(RefCell::new((b.as_pointer()).reinterpret_cast::<u32>()));`
`15`	`15`	`let val: Value<u32> = Rc::new(RefCell::new(((*p.borrow()).read())));`
	`16`	`+ (*val.borrow_mut());`
`16`	`17`	`return 0;`
`17`	`18`	`}`