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Add custom deleter support to UniquePtr #1305

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Add custom deleter support to UniquePtr #1305

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2b822f8
Add custom deleter support to UniquePtr
darkwisebear Dec 12, 2023
8336f62
Fix failing tests on Linux
darkwisebear Jan 11, 2024
424dcba
Support unique_ptr deleter as 2nd member
darkwisebear Jan 13, 2024
2b73827
Add missing repr(C) to DefaultDeleter
darkwisebear Jan 30, 2024
a6b3bed
Fix UI tests
darkwisebear Jan 30, 2024
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5 changes: 3 additions & 2 deletions book/src/binding/uniqueptr.md
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Original file line number Diff line number Diff line change
Expand Up @@ -8,8 +8,9 @@ the link for documentation of the Rust API.

### Restrictions:

Only `std::unique_ptr<T, std::default_delete<T>>` is currently supported. Custom
deleters may be supported in the future.
If a custom deleter is used, it needs to be a type that is
[shared between C++ and Rust](../shared.md) so that the instance of UniquePtr can still
be passed by value in Rust code.

UniquePtr\<T\> does not support T being an opaque Rust type. You should use a
Box\<T\> (C++ [rust::Box\<T\>](box.md)) instead for transferring ownership of
Expand Down
126 changes: 87 additions & 39 deletions gen/src/write.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -823,8 +823,7 @@ fn write_cxx_function_shim<'a>(out: &mut OutFile<'a>, efn: &'a ExternFn) {
write_type(out, &arg.ty);
write!(out, "::from_raw({})", arg.name.cxx);
} else if let Type::UniquePtr(_) = &arg.ty {
write_type(out, &arg.ty);
write!(out, "({})", arg.name.cxx);
write!(out, "::std::move(*{})", arg.name.cxx);
} else if arg.ty == RustString {
out.builtin.unsafe_bitcopy = true;
write!(
Expand All @@ -846,7 +845,6 @@ fn write_cxx_function_shim<'a>(out: &mut OutFile<'a>, efn: &'a ExternFn) {
write!(out, ")");
match &efn.ret {
Some(Type::RustBox(_)) => write!(out, ".into_raw()"),
Some(Type::UniquePtr(_)) => write!(out, ".release()"),
Some(Type::Str(_) | Type::SliceRef(_)) if !indirect_return => write!(out, ")"),
_ => {}
}
Expand Down Expand Up @@ -1092,7 +1090,6 @@ fn write_rust_function_shim_impl(
write!(out, "{}", arg.name.cxx);
match &arg.ty {
Type::RustBox(_) => write!(out, ".into_raw()"),
Type::UniquePtr(_) => write!(out, ".release()"),
ty if ty != RustString && out.types.needs_indirect_abi(ty) => write!(out, "$.value"),
_ => {}
}
Expand Down Expand Up @@ -1155,10 +1152,19 @@ fn indirect_return(sig: &Signature, types: &Types) -> bool {

fn write_indirect_return_type(out: &mut OutFile, ty: &Type) {
match ty {
Type::RustBox(ty) | Type::UniquePtr(ty) => {
Type::RustBox(ty) => {
write_type_space(out, &ty.inner);
write!(out, "*");
}
Type::UniquePtr(ty) => {
write!(out, "::std::unique_ptr<");
write_type(out, &ty.first);
if let Some(deleter) = &ty.second {
write!(out, ", ");
write_type(out, deleter);
}
write!(out, "> ");
}
Type::Ref(ty) => {
write_type_space(out, &ty.inner);
if !ty.mutable {
Expand All @@ -1181,7 +1187,7 @@ fn write_indirect_return_type_space(out: &mut OutFile, ty: &Type) {

fn write_extern_return_type_space(out: &mut OutFile, ty: &Option<Type>) {
match ty {
Some(Type::RustBox(ty) | Type::UniquePtr(ty)) => {
Some(Type::RustBox(ty)) => {
write_type_space(out, &ty.inner);
write!(out, "*");
}
Expand All @@ -1203,7 +1209,7 @@ fn write_extern_return_type_space(out: &mut OutFile, ty: &Option<Type>) {

fn write_extern_arg(out: &mut OutFile, arg: &Var) {
match &arg.ty {
Type::RustBox(ty) | Type::UniquePtr(ty) | Type::CxxVector(ty) => {
Type::RustBox(ty) | Type::CxxVector(ty) => {
write_type_space(out, &ty.inner);
write!(out, "*");
}
Expand Down Expand Up @@ -1237,7 +1243,11 @@ fn write_type(out: &mut OutFile, ty: &Type) {
}
Type::UniquePtr(ptr) => {
write!(out, "::std::unique_ptr<");
write_type(out, &ptr.inner);
write_type(out, &ptr.first);
if let Some(deleter) = &ptr.second {
write!(out, ", ");
write_type(out, deleter);
}
write!(out, ">");
}
Type::SharedPtr(ptr) => {
Expand Down Expand Up @@ -1350,7 +1360,7 @@ fn write_space_after_type(out: &mut OutFile, ty: &Type) {

#[derive(Copy, Clone)]
enum UniquePtr<'a> {
Ident(&'a Ident),
Ident(&'a Ident, Option<&'a Ident>),
CxxVector(&'a Ident),
}

Expand All @@ -1367,7 +1377,7 @@ impl ToTypename for Ident {
impl<'a> ToTypename for UniquePtr<'a> {
fn to_typename(&self, types: &Types) -> String {
match self {
UniquePtr::Ident(ident) => ident.to_typename(types),
UniquePtr::Ident(ident, _) => ident.to_typename(types),
UniquePtr::CxxVector(element) => {
format!("::std::vector<{}>", element.to_typename(types))
}
Expand All @@ -1388,7 +1398,7 @@ impl ToMangled for Ident {
impl<'a> ToMangled for UniquePtr<'a> {
fn to_mangled(&self, types: &Types) -> Symbol {
match self {
UniquePtr::Ident(ident) => ident.to_mangled(types),
UniquePtr::Ident(ident, _) => ident.to_mangled(types),
UniquePtr::CxxVector(element) => {
symbol::join(&[&"std", &"vector", &element.to_mangled(types)])
}
Expand All @@ -1409,7 +1419,7 @@ fn write_generic_instantiations(out: &mut OutFile) {
match *impl_key {
ImplKey::RustBox(ident) => write_rust_box_extern(out, ident),
ImplKey::RustVec(ident) => write_rust_vec_extern(out, ident),
ImplKey::UniquePtr(ident) => write_unique_ptr(out, ident),
ImplKey::UniquePtr(ident, deleter) => write_unique_ptr(out, ident, deleter),
ImplKey::SharedPtr(ident) => write_shared_ptr(out, ident),
ImplKey::WeakPtr(ident) => write_weak_ptr(out, ident),
ImplKey::CxxVector(ident) => write_cxx_vector(out, ident),
Expand Down Expand Up @@ -1621,8 +1631,8 @@ fn write_rust_vec_impl(out: &mut OutFile, key: NamedImplKey) {
writeln!(out, "}}");
}

fn write_unique_ptr(out: &mut OutFile, key: NamedImplKey) {
let ty = UniquePtr::Ident(key.rust);
fn write_unique_ptr(out: &mut OutFile, key: NamedImplKey, deleter: Option<&Ident>) {
let ty = UniquePtr::Ident(key.rust, deleter);
write_unique_ptr_common(out, ty);
}

Expand All @@ -1632,18 +1642,34 @@ fn write_unique_ptr_common(out: &mut OutFile, ty: UniquePtr) {
out.include.utility = true;
let inner = ty.to_typename(out.types);
let instance = ty.to_mangled(out.types);
let (cxx_type_string, mangled_prefix, deleter_name) =
if let UniquePtr::Ident(_, Some(deleter)) = &ty {
let deleter_instance = deleter.to_mangled(out.types);
let deleter_inner = deleter.to_typename(out.types);
(
format!("::std::unique_ptr<{}, {}>", inner, &deleter_inner),
format!("cxxbridge1$unique_ptr${}${}$", instance, deleter_instance),
Some(deleter_inner),
)
} else {
(
format!("::std::unique_ptr<{}>", inner),
format!("cxxbridge1$unique_ptr${}$", instance),
None,
)
};

let can_construct_from_value = match ty {
// Some aliases are to opaque types; some are to trivial types. We can't
// know at code generation time, so we generate both C++ and Rust side
// bindings for a "new" method anyway. But the Rust code can't be called
// for Opaque types because the 'new' method is not implemented.
UniquePtr::Ident(ident) => out.types.is_maybe_trivial(ident),
UniquePtr::Ident(ident, _) => out.types.is_maybe_trivial(ident),
UniquePtr::CxxVector(_) => false,
};

let conditional_delete = match ty {
UniquePtr::Ident(ident) => {
UniquePtr::Ident(ident, _) => {
!out.types.structs.contains_key(ident) && !out.types.enums.contains_key(ident)
}
UniquePtr::CxxVector(_) => false,
Expand All @@ -1652,7 +1678,7 @@ fn write_unique_ptr_common(out: &mut OutFile, ty: UniquePtr) {
if conditional_delete {
out.builtin.is_complete = true;
let definition = match ty {
UniquePtr::Ident(ty) => &out.types.resolve(ty).name.cxx,
UniquePtr::Ident(ty, _) => &out.types.resolve(ty).name.cxx,
UniquePtr::CxxVector(_) => unreachable!(),
};
writeln!(
Expand All @@ -1661,22 +1687,36 @@ fn write_unique_ptr_common(out: &mut OutFile, ty: UniquePtr) {
inner, definition,
);
}
writeln!(
out,
"static_assert(sizeof(::std::unique_ptr<{}>) == sizeof(void *), \"\");",
inner,
);
writeln!(
out,
"static_assert(alignof(::std::unique_ptr<{}>) == alignof(void *), \"\");",
inner,
);
if let Some(deleter_name) = &deleter_name {
writeln!(
out,
"static_assert(sizeof(::std::unique_ptr<{inner}, {deleter_name}>) >= (sizeof(void *) + \
sizeof({deleter_name})), \"Implausible size of unique_ptr with deleter {deleter_name}\");",
);
out.include.type_traits = true;
writeln!(
out,
"static_assert(std::is_trivially_move_constructible<{deleter_name}>::value && std::is_trivially_destructible<{deleter_name}>::value, \
\"Only trivial types are supported as deleter for unique_ptr\");",
)
} else {
writeln!(
out,
"static_assert(sizeof(::std::unique_ptr<{}>) == sizeof(void *), \"\");",
inner,
);
writeln!(
out,
"static_assert(alignof(::std::unique_ptr<{}>) == alignof(void *), \"\");",
inner,
);
}

begin_function_definition(out);
writeln!(
out,
"void cxxbridge1$unique_ptr${}$null(::std::unique_ptr<{}> *ptr) noexcept {{",
instance, inner,
"void {}null(::std::unique_ptr<{}> *ptr) noexcept {{",
mangled_prefix, inner,
);
writeln!(out, " ::new (ptr) ::std::unique_ptr<{}>();", inner);
writeln!(out, "}}");
Expand All @@ -1686,8 +1726,8 @@ fn write_unique_ptr_common(out: &mut OutFile, ty: UniquePtr) {
begin_function_definition(out);
writeln!(
out,
"{} *cxxbridge1$unique_ptr${}$uninit(::std::unique_ptr<{}> *ptr) noexcept {{",
inner, instance, inner,
"{} *{}uninit(::std::unique_ptr<{}> *ptr) noexcept {{",
inner, mangled_prefix, inner,
);
writeln!(
out,
Expand All @@ -1702,36 +1742,44 @@ fn write_unique_ptr_common(out: &mut OutFile, ty: UniquePtr) {
begin_function_definition(out);
writeln!(
out,
"void cxxbridge1$unique_ptr${}$raw(::std::unique_ptr<{}> *ptr, {} *raw) noexcept {{",
instance, inner, inner,
"void {}raw(::std::unique_ptr<{}> *ptr, {} *raw) noexcept {{",
mangled_prefix, inner, inner,
);
writeln!(out, " ::new (ptr) ::std::unique_ptr<{}>(raw);", inner);
writeln!(out, "}}");

begin_function_definition(out);
writeln!(
out,
"{} const *cxxbridge1$unique_ptr${}$get(::std::unique_ptr<{}> const &ptr) noexcept {{",
inner, instance, inner,
"{} const *{}get(::std::unique_ptr<{}> const &ptr) noexcept {{",
inner, mangled_prefix, inner,
);
writeln!(out, " return ptr.get();");
writeln!(out, "}}");

begin_function_definition(out);
writeln!(
out,
"{} *cxxbridge1$unique_ptr${}$release(::std::unique_ptr<{}> &ptr) noexcept {{",
inner, instance, inner,
"{} *{}release(::std::unique_ptr<{}> &ptr) noexcept {{",
inner, mangled_prefix, inner,
);
writeln!(out, " return ptr.release();");
writeln!(out, "}}");

begin_function_definition(out);
writeln!(
out,
"void cxxbridge1$unique_ptr${}$drop(::std::unique_ptr<{}> *ptr) noexcept {{",
instance, inner,
"void {}drop({} *ptr) noexcept {{",
mangled_prefix, &cxx_type_string,
);
if deleter_name.is_some() {
// Check whether the deleter is really the first member as expected by the Rust type
out.include.cassert = true;
#[cfg(not(target_os = "macos"))]
writeln!(out, " assert(reinterpret_cast<void*>(&ptr->get_deleter()) == reinterpret_cast<void*>(ptr));");
#[cfg(target_os = "macos")]
writeln!(out, " assert(reinterpret_cast<char*>(&ptr->get_deleter()) >= reinterpret_cast<char*>(ptr) + sizeof(void*));");
}
if conditional_delete {
out.builtin.deleter_if = true;
writeln!(
Expand Down
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