Fix const_cast for references

Author: lucic71

cpp2rust/converter/converter.cpp

@@ -2767,7 +2767,28 @@ bool Converter::VisitExplicitCastExpr(clang::ExplicitCastExpr *expr) {
   }
   // A cast to a reference type only rebinds the operand, it converts nothing
   if (type->isReferenceType()) {
-    Convert(sub_expr);
+    const char *suffix = nullptr;
+    if (isAddrOf()) {
+      switch (
+          GetConstCastType(type.getNonReferenceType(), sub_expr->getType())) {
+      case ConstCastType::MutableToConst:
+        suffix = ".cast_const()";
+        break;
+      case ConstCastType::ConstToMutable:
+        suffix = ".cast_mut()";
+        break;
+      default:
+        break;
+      }
+    }
+    {
+      PushParen paren(*this, suffix);
+      Convert(sub_expr);
+    }
+    if (suffix) {
+      StrCat(suffix);
+      computed_expr_type_ = ComputedExprType::FreshPointer;
+    }
     return false;
   }
   switch (expr->getStmtClass()) {

tests/unit/unconst.cpp

@@ -4,10 +4,22 @@
 
 #define UNCONST(p) ((void *)(uintptr_t)(const void *)(p))
 
+void set(int &r) { r = 7; }
+
+template <typename T> void set_through(const T &v) { set(const_cast<T &>(v)); }
+
 int main() {
   const int a = 1;
   const int *p = &a;
   auto q = static_cast<int *>(UNCONST(p));
   assert(p == q);
+
+  int v = 1;
+  const int &cr = v;
+  set(const_cast<int &>(cr));
+  assert(v == 7);
+  v = 0;
+  set_through(v);
+  assert(v == 7);
   return 0;
 }