Translate va_list references and pointers in fields

Author: lucic71

cpp2rust/converter/models/converter_refcount.cpp

@@ -291,7 +291,7 @@ bool ConverterRefCount::VisitReferenceType(clang::ReferenceType *type) {
     PushConversionKind push(*this, ConversionKind::Unboxed);
     return Convert(ctx_.getPointerType(pointee_type));
   }
-  if (pointee_type->isArrayType()) {
+  if (pointee_type->isArrayType() && !IsVaListType(pointee_type)) {
     // A reference to an array decays straight to a pointer to its first
     // element, the same way a by-value array parameter would, instead of
     // going through a pointer to the whole boxed array.
@@ -335,10 +335,11 @@ bool ConverterRefCount::VisitPointerType(clang::PointerType *type) {
   }
 
   auto pointee_type = type->getPointeeType();
-  PushConversionKind push1(*this, ConversionKind::Ptr,
-                           !pointee_type->isArrayType());
+  bool pointee_is_array =
+      pointee_type->isArrayType() && !IsVaListType(pointee_type);
+  PushConversionKind push1(*this, ConversionKind::Ptr, !pointee_is_array);
   PushConversionKind push2(*this, ConversionKind::FullRefCount,
-                           pointee_type->isArrayType());
+                           pointee_is_array);
   if (pointee_type->isRecordType() &&
       abstract_structs_.contains(GetID(pointee_type->getAsRecordDecl()))) {
     StrCat("PtrDyn<dyn");
@@ -2462,13 +2463,18 @@ bool ConverterRefCount::VisitVAArgExpr(clang::VAArgExpr *expr) {
   if (auto *cast = clang::dyn_cast<clang::ImplicitCastExpr>(va_list_expr)) {
     va_list_expr = cast->getSubExpr();
   }
-  StrCat(ConvertLValue(va_list_expr));
-  StrCat(".arg::<");
+  auto str = ConvertLValue(va_list_expr);
+  std::string arg_type;
   {
     PushConversionKind push(*this, ConversionKind::Unboxed);
-    StrCat(ToString(expr->getType()));
+    arg_type = ToString(expr->getType());
+  }
+  if (!pending_deref_.empty()) {
+    StrCat(pending_deref_.take(), ".with_mut(|__v| __v.arg::<", arg_type,
+           ">())");
+  } else {
+    StrCat(str, ".arg::<", arg_type, ">()");
   }
-  StrCat(">()");
   SetFreshType(expr->getType());
   return false;
 }

libcc2rs/src/va_args.rs

@@ -52,15 +52,20 @@ impl<T: crate::reinterpret::ByteRepr + 'static> From<crate::rc::Ptr<T>> for VaAr
     }
 }
 
-#[derive(Clone, Copy, Default)]
-pub struct VaList<'a> {
-    args: &'a [VaArg],
+#[derive(Clone, Default)]
+pub struct VaList {
+    args: Rc<[VaArg]>,
     pos: usize,
 }
 
-impl<'a> VaList<'a> {
-    pub fn new(args: &'a [VaArg]) -> Self {
-        VaList { args, pos: 0 }
+impl crate::reinterpret::ByteRepr for VaList {}
+
+impl VaList {
+    pub fn new(args: &[VaArg]) -> Self {
+        VaList {
+            args: Rc::from(args),
+            pos: 0,
+        }
     }
 
     pub fn arg<T: VaArgGet>(&mut self) -> T {

tests/unit/va_list_field.cpp

@@ -0,0 +1,44 @@
+#include <cassert>
+#include <cstdarg>
+
+static int sum(int n, ...) {
+  struct Guard {
+    va_list &ap;
+    bool active;
+    Guard(va_list &val) : ap(val), active(true) {}
+    ~Guard() {
+      if (active) {
+        va_end(ap);
+      }
+    }
+  };
+  va_list ap;
+  va_start(ap, n);
+  Guard guard(ap);
+  int total = 0;
+  for (int i = 0; i < n; ++i) {
+    total += va_arg(guard.ap, int);
+  }
+  return total;
+}
+
+static int sum_ptr(int n, ...) {
+  struct Cursor {
+    va_list *ap;
+  };
+  va_list ap;
+  va_start(ap, n);
+  Cursor cursor{&ap};
+  int total = 0;
+  for (int i = 0; i < n; ++i) {
+    total += va_arg(*cursor.ap, int);
+  }
+  va_end(ap);
+  return total;
+}
+
+int main() {
+  assert(sum(3, 1, 2, 3) == 6);
+  assert(sum_ptr(2, 4, 5) == 9);
+  return 0;
+}