Fix list initializers for unions (#514)

Author: lucic71

cpp2rust/converter/converter.cpp

@@ -3573,6 +3573,14 @@ bool Converter::VisitInitListExpr(clang::InitListExpr *expr) {
 
     StrCat(GetUnsafeTypeAsString(qual_type));
     PushBrace brace(*this);
+    if (record->isUnion()) {
+      auto *field = expr->getInitializedFieldInUnion();
+      assert(field && expr->getNumInits() == 1);
+      StrCat(GetNamedDeclAsString(field), token::kColon);
+      ConvertFieldInit(field, expr->getInit(0));
+      SetFreshType(qual_type);
+      return false;
+    }
     int i = 0;
     for (const auto *field : record->fields()) {
       StrCat(GetNamedDeclAsString(field), token::kColon);

cpp2rust/converter/models/converter_refcount.cpp

@@ -1908,6 +1908,21 @@ bool ConverterRefCount::VisitInitListExpr(clang::InitListExpr *expr) {
       return false;
     }
 
+    if (record->isUnion()) {
+      auto *field = expr->getInitializedFieldInUnion();
+      assert(field && expr->getNumInits() == 1);
+      PushConversionKind push(*this, ConversionKind::Unboxed);
+      auto name = GetUnsafeTypeAsString(qual_type);
+      StrCat(std::format("{{ let __u: Value<{}> = Rc::new(RefCell::new({}));",
+                         name, GetDefaultAsString(qual_type)));
+      StrCat(std::format("{}::{}(__u.as_pointer()).write(", name,
+                         GetNamedDeclAsString(field)));
+      ConvertVarInit(field->getType(), expr->getInit(0));
+      StrCat("); Rc::try_unwrap(__u).ok().unwrap().into_inner() }");
+      computed_expr_type_ = ComputedExprType::FreshValue;
+      return false;
+    }
+
     StrCat(GetUnsafeTypeAsString(qual_type));
     {
       PushBrace brace(*this);

tests/unit/out/refcount/union_basic.rs

@@ -93,6 +93,18 @@ fn main_0() -> i32 {
     assert!(((basic::i(ru.clone()).read()) == 1065353216));
     assert!(((pf.read()) == 1_f32));
     assert!((((*buf.borrow())[(3) as usize] as i32) == 63));
+    let braced: Value<basic> = Rc::new(RefCell::new({
+        let __u: Value<basic> = Rc::new(RefCell::new(<basic>::default()));
+        basic::i(__u.as_pointer()).write(5);
+        Rc::try_unwrap(__u).ok().unwrap().into_inner()
+    }));
+    assert!(((basic::i(braced.as_pointer()).read()) == 5));
+    let copied: Value<basic> = Rc::new(RefCell::new({
+        let __u: Value<basic> = Rc::new(RefCell::new(<basic>::default()));
+        basic::i(__u.as_pointer()).write(7);
+        Rc::try_unwrap(__u).ok().unwrap().into_inner()
+    }));
+    assert!(((basic::i(copied.as_pointer()).read()) == 7));
     {
         let anon_0: Value<anon_0> = Rc::new(RefCell::new(<anon_0>::default()));
         anon_0::ai(anon_0.as_pointer()).write(11);

tests/unit/out/unsafe/union_basic.rs

@@ -69,6 +69,10 @@ unsafe fn main_0() -> i32 {
     assert!((((*ru).i) == (1065353216)));
     assert!(((*pf) == (1_f32)));
     assert!(((buf[(3) as usize] as i32) == (63)));
+    let mut braced: basic = basic { i: 5 };
+    assert!(((braced.i) == (5)));
+    let mut copied: basic = basic { i: 7 };
+    assert!(((copied.i) == (7)));
     {
         let mut anon_0: anon_0 = <anon_0>::default();
         anon_0.ai = 11;

tests/unit/union_basic.cpp

@@ -38,6 +38,11 @@ int main(void) {
   assert(*pf == 1.0f);
   assert(buf[3] == 0x3F);
 
+  union basic braced{5};
+  assert(braced.i == 5);
+  union basic copied = {7};
+  assert(copied.i == 7);
+
   {
     union {
       int ai;