Use default string literal instead of <S>::default()

Author: lucic71

cpp2rust/converter/converter.cpp

@@ -4048,16 +4048,9 @@ std::string Converter::GetDefaultAsStringFallback(clang::QualType qual_type) {
     return getTypedLiteral("0.0", ToString(qual_type));
   }
 
-  if (auto record = qual_type->getAsRecordDecl();
-      record && in_const_initializer_) {
-    if (auto cxx = clang::dyn_cast<clang::CXXRecordDecl>(record)) {
-      ENSURE(GetUserDefinedDefaultConstructor(cxx) == nullptr &&
-             "Default initializing globals using default constructor is not "
-             "supported");
-    }
-    Buffer buf(*this);
-    EmitDefaultStructLiteral(record);
-    return std::move(buf).str();
+  if (auto literal = GetDefaultStructLiteralAsString(qual_type);
+      !literal.empty()) {
+    return literal;
   }
 
   if (auto record = qual_type->getAsRecordDecl()) {
@@ -4079,6 +4072,21 @@ std::string Converter::GetDefaultAsStringFallback(clang::QualType qual_type) {
   return std::format("<{}>::default()", ToString(qual_type));
 }
 
+std::string
+Converter::GetDefaultStructLiteralAsString(clang::QualType qual_type) {
+  auto *record = qual_type->getAsRecordDecl();
+  if (record == nullptr || record->isUnion()) {
+    return {};
+  }
+  if (auto *cxx = clang::dyn_cast<clang::CXXRecordDecl>(record);
+      cxx && GetUserDefinedDefaultConstructor(cxx)) {
+    return {};
+  }
+  Buffer buf(*this);
+  EmitDefaultStructLiteral(record);
+  return std::move(buf).str();
+}
+
 std::string Converter::ConvertVarDefaultInit(clang::QualType qual_type) {
   return GetDefaultAsString(qual_type);
 }

cpp2rust/converter/converter.h

@@ -552,6 +552,9 @@ class Converter : public clang::RecursiveASTVisitor<Converter> {
 
   virtual std::string GetDefaultAsStringFallback(clang::QualType qual_type);
 
+  virtual std::string
+  GetDefaultStructLiteralAsString(clang::QualType qual_type);
+
   virtual std::string ConvertVarDefaultInit(clang::QualType qual_type);
 
   virtual std::string

cpp2rust/converter/models/converter_refcount.cpp

@@ -2187,7 +2187,22 @@ std::string ConverterRefCount::GetDefaultAsString(clang::QualType qual_type) {
 
 std::string
 ConverterRefCount::GetDefaultAsStringFallback(clang::QualType qual_type) {
-  return std::format("<{}>::default()", ToString(qual_type));
+  if (qual_type->isReferenceType()) {
+    return Converter::GetDefaultAsStringFallback(qual_type);
+  }
+
+  std::string unboxed;
+  {
+    PushConversionKind push(*this, ConversionKind::Unboxed);
+    unboxed = Converter::GetDefaultAsStringFallback(qual_type);
+  }
+  return BoxValue(std::move(unboxed));
+}
+
+std::string
+ConverterRefCount::GetDefaultStructLiteralAsString(clang::QualType qual_type) {
+  PushConversionKind push(*this, ConversionKind::FullRefCount);
+  return Converter::GetDefaultStructLiteralAsString(qual_type);
 }
 
 std::string

cpp2rust/converter/models/converter_refcount.h

@@ -182,6 +182,9 @@ class ConverterRefCount final : public Converter {
 
   std::string GetDefaultAsStringFallback(clang::QualType qual_type) override;
 
+  std::string
+  GetDefaultStructLiteralAsString(clang::QualType qual_type) override;
+
   std::string ConvertVarDefaultInit(clang::QualType qual_type) override;
 
   std::vector<const char *>

tests/multi-file/cross_tu_tag_collision/out/refcount/cross_tu_tag_collision.rs

@@ -31,7 +31,9 @@ impl ByteRepr for widget {
     }
 }
 pub fn a_value_0() -> i32 {
-    let w: Value<widget> = <Value<widget>>::default();
+    let w: Value<widget> = Rc::new(RefCell::new(widget {
+        id: Rc::new(RefCell::new(0_i32)),
+    }));
     (*(*w.borrow()).id.borrow_mut()) = 11;
     return (*(*w.borrow()).id.borrow());
 }

tests/multi-file/cross_tu_tag_collision/out/unsafe/cross_tu_tag_collision.rs

@@ -12,7 +12,7 @@ pub struct widget {
     pub id: i32,
 }
 pub unsafe fn a_value_0() -> i32 {
-    let mut w: widget = <widget>::default();
+    let mut w: widget = widget { id: 0_i32 };
     w.id = 11;
     return w.id;
 }

tests/multi-file/defaulted_move_cross_tu/out/refcount/defaulted_move_cross_tu.rs

@@ -41,9 +41,7 @@ impl Default for S {
     fn default() -> Self {
         S {
             v: Rc::new(RefCell::new(Default::default())),
-            n: Rc::new(RefCell::new(
-                (0..2).map(|_| <i32>::default()).collect::<Box<[i32]>>(),
-            )),
+            n: Rc::new(RefCell::new((0..2).map(|_| 0_i32).collect::<Box<[i32]>>())),
         }
     }
 }

tests/multi-file/template_method_late_instantiation/out/refcount/template_method_late_instantiation.rs

@@ -44,7 +44,9 @@ pub fn main() {
     std::process::exit(main_0());
 }
 fn main_0() -> i32 {
-    let p: Value<S_int_> = Rc::new(RefCell::new(<S_int_>::default()));
+    let p: Value<S_int_> = Rc::new(RefCell::new(S_int_ {
+        x: Rc::new(RefCell::new(0)),
+    }));
     ({ S_int_Impl::set(&p.as_pointer(), 3) });
     assert!((({ f_0((p.as_pointer()),) }) == 3));
     return 0;

tests/multi-file/template_method_late_instantiation/out/unsafe/template_method_late_instantiation.rs

@@ -28,7 +28,7 @@ pub fn main() {
     }
 }
 unsafe fn main_0() -> i32 {
-    let mut p: S_int_ = <S_int_>::default();
+    let mut p: S_int_ = S_int_ { x: 0 };
     (unsafe { S_int_::set(&mut p, 3) });
     assert!(((unsafe { f_0((&mut p as *mut S_int_),) }) == (3)));
     return 0;

tests/ub/out/refcount/fd_use_after_close.rs

@@ -31,9 +31,7 @@ fn main_0() -> i32 {
         }
     }));
     FdRegistry::close((*fd.borrow()));
-    let buf: Value<Box<[u8]>> = Rc::new(RefCell::new(
-        (0..4).map(|_| <u8>::default()).collect::<Box<[u8]>>(),
-    ));
+    let buf: Value<Box<[u8]>> = Rc::new(RefCell::new((0..4).map(|_| 0_u8).collect::<Box<[u8]>>()));
     let n: Value<isize> = Rc::new(RefCell::new(
         match FdRegistry::with_fd((*fd.borrow()), |__fd| {
             ((buf.as_pointer() as Ptr<u8>) as Ptr<u8>)