15200164445

Committed 23 May 2025 01:21AM UTC coverage: 57.288% (+0.1%) from 57.185%

Build # 15200164445

Build Type

Pull #666

github

Committed by

web-flow

Commit Message

Merge 4232978c5 into 4b41e5c8a

Pull Request Pull Request #666: Add indirection to vtable fns to fix cyclic types

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65.9

/facet-core/src/impls_alloc/rc.rs

use crate::{
    Def, Facet, KnownSmartPointer, PtrConst, PtrMut, PtrUninit, Shape, SmartPointerDef,
    SmartPointerFlags, SmartPointerVTable, TryBorrowInnerError, TryFromError, TryIntoInnerError,
    Type, UserType, ValueVTable, value_vtable,
};

unsafe impl<'a, T: Facet<'a>> Facet<'a> for alloc::rc::Rc<T> {
    const VTABLE: &'static ValueVTable = &const {
        // Define the functions for transparent conversion between Rc<T> and T
        unsafe fn try_from<'a, 'shape, 'src, 'dst, T: Facet<'a>>(
            src_ptr: PtrConst<'src>,
            src_shape: &'shape Shape<'shape>,
            dst: PtrUninit<'dst>,
        ) -> Result<PtrMut<'dst>, TryFromError<'shape>> {
            if src_shape.id != T::SHAPE.id {
                return Err(TryFromError::UnsupportedSourceShape {
                    src_shape,
                    expected: &[T::SHAPE],
                });
            }
            let t = unsafe { src_ptr.read::<T>() };
            let rc = alloc::rc::Rc::new(t);
            Ok(unsafe { dst.put(rc) })
        }

        unsafe fn try_into_inner<'a, 'src, 'dst, T: Facet<'a>>(
            src_ptr: PtrMut<'src>,
            dst: PtrUninit<'dst>,
        ) -> Result<PtrMut<'dst>, TryIntoInnerError> {
            let rc = unsafe { src_ptr.get::<alloc::rc::Rc<T>>() };
            match alloc::rc::Rc::try_unwrap(rc.clone()) {
                Ok(t) => Ok(unsafe { dst.put(t) }),
                Err(_) => Err(TryIntoInnerError::Unavailable),
            }
        }

        unsafe fn try_borrow_inner<'a, 'src, T: Facet<'a>>(
            src_ptr: PtrConst<'src>,
        ) -> Result<PtrConst<'src>, TryBorrowInnerError> {
            let rc = unsafe { src_ptr.get::<alloc::rc::Rc<T>>() };
            Ok(PtrConst::new(&**rc))
        }

        let mut vtable = value_vtable!(alloc::rc::Rc<T>, |f, opts| {
            write!(f, "Rc")?;
            if let Some(opts) = opts.for_children() {
                write!(f, "<")?;
                (T::SHAPE.vtable.type_name)(f, opts)?;
                write!(f, ">")?;
            } else {
                write!(f, "<…>")?;
            }
            Ok(())
        });
        vtable.try_from = || Some(try_from::<T>);
        vtable.try_into_inner = || Some(try_into_inner::<T>);
        vtable.try_borrow_inner = || Some(try_borrow_inner::<T>);
        vtable
    };

    const SHAPE: &'static crate::Shape<'static> = &const {
        // Function to return inner type's shape
        fn inner_shape<'a, T: Facet<'a>>() -> &'static Shape<'static> {
            T::SHAPE
        }

        crate::Shape::builder_for_sized::<Self>()
            .type_params(&[crate::TypeParam {
                name: "T",
                shape: || T::SHAPE,
            }])
            .ty(Type::User(UserType::Opaque))
            .def(Def::SmartPointer(
                SmartPointerDef::builder()
                    .pointee(|| T::SHAPE)
                    .flags(SmartPointerFlags::EMPTY)
                    .known(KnownSmartPointer::Rc)
                    .weak(|| <alloc::rc::Weak<T> as Facet>::SHAPE)
                    .vtable(
                        &const {
                            SmartPointerVTable::builder()
                                .borrow_fn(|this| {
                                    let ptr = Self::as_ptr(unsafe { this.get() });
                                    PtrConst::new(ptr)
                                })
                                .new_into_fn(|this, ptr| {
                                    let t = unsafe { ptr.read::<T>() };
                                    let rc = alloc::rc::Rc::new(t);
                                    unsafe { this.put(rc) }
                                })
                                .downgrade_into_fn(|strong, weak| unsafe {
                                    weak.put(alloc::rc::Rc::downgrade(strong.get::<Self>()))
                                })
                                .build()
                        },
                    )
                    .build(),
            ))
            .inner(inner_shape::<T>)
            .build()
    };
}

unsafe impl<'a, T: Facet<'a>> Facet<'a> for alloc::rc::Weak<T> {
    const VTABLE: &'static ValueVTable = &const {
        value_vtable!(alloc::rc::Weak<T>, |f, opts| {
            write!(f, "Weak")?;
            if let Some(opts) = opts.for_children() {
                write!(f, "<")?;
                (T::SHAPE.vtable.type_name)(f, opts)?;
                write!(f, ">")?;
            } else {
                write!(f, "<…>")?;
            }
            Ok(())
        })
    };

    const SHAPE: &'static crate::Shape<'static> = &const {
        // Function to return inner type's shape
        fn inner_shape<'a, T: Facet<'a>>() -> &'static Shape<'static> {
            T::SHAPE
        }

        crate::Shape::builder_for_sized::<Self>()
            .type_params(&[crate::TypeParam {
                name: "T",
                shape: || T::SHAPE,
            }])
            .ty(Type::User(UserType::Opaque))
            .def(Def::SmartPointer(
                SmartPointerDef::builder()
                    .pointee(|| T::SHAPE)
                    .flags(SmartPointerFlags::WEAK)
                    .known(KnownSmartPointer::RcWeak)
                    .strong(|| <alloc::rc::Rc<T> as Facet>::SHAPE)
                    .vtable(
                        &const {
                            SmartPointerVTable::builder()
                                .upgrade_into_fn(|weak, strong| unsafe {
                                    Some(strong.put(weak.get::<Self>().upgrade()?))
                                })
                                .build()
                        },
                    )
                    .build(),
            ))
            .inner(inner_shape::<T>)
            .build()
    };
}

#[cfg(test)]
mod tests {
    use alloc::rc::{Rc, Weak as RcWeak};
    use alloc::string::String;

    use super::*;

    #[test]
    fn test_rc_type_params() {
        let [type_param_1] = <Rc<i32>>::SHAPE.type_params else {
            panic!("Rc<T> should only have 1 type param")
        };
        assert_eq!(type_param_1.shape(), i32::SHAPE);
    }

    #[test]
    fn test_rc_vtable_1_new_borrow_drop() -> eyre::Result<()> {
        facet_testhelpers::setup();

        let rc_shape = <Rc<String>>::SHAPE;
        let rc_def = rc_shape
            .def
            .into_smart_pointer()
            .expect("Rc<T> should have a smart pointer definition");

        // Allocate memory for the Rc
        let rc_uninit_ptr = rc_shape.allocate()?;

        // Get the function pointer for creating a new Rc from a value
        let new_into_fn = rc_def
            .vtable
            .new_into_fn
            .expect("Rc<T> should have new_into_fn");

        // Create the value and initialize the Rc
        let mut value = String::from("example");
        let rc_ptr = unsafe { new_into_fn(rc_uninit_ptr, PtrMut::new(&raw mut value)) };
        // The value now belongs to the Rc, prevent its drop
        core::mem::forget(value);

        // Get the function pointer for borrowing the inner value
        let borrow_fn = rc_def
            .vtable
            .borrow_fn
            .expect("Rc<T> should have borrow_fn");

        // Borrow the inner value and check it
        let borrowed_ptr = unsafe { borrow_fn(rc_ptr.as_const()) };
        // SAFETY: borrowed_ptr points to a valid String within the Rc
        assert_eq!(unsafe { borrowed_ptr.get::<String>() }, "example");

        // Get the function pointer for dropping the Rc
        let drop_fn = (rc_shape.vtable.drop_in_place)().expect("Rc<T> should have drop_in_place");

        // Drop the Rc in place
        // SAFETY: rc_ptr points to a valid Rc<String>
        unsafe { drop_fn(rc_ptr) };

        // Deallocate the memory
        // SAFETY: rc_ptr was allocated by rc_shape and is now dropped (but memory is still valid)
        unsafe { rc_shape.deallocate_mut(rc_ptr)? };

        Ok(())
    }

    #[test]
    fn test_rc_vtable_2_downgrade_upgrade_drop() -> eyre::Result<()> {
        facet_testhelpers::setup();

        let rc_shape = <Rc<String>>::SHAPE;
        let rc_def = rc_shape
            .def
            .into_smart_pointer()
            .expect("Rc<T> should have a smart pointer definition");

        let weak_shape = <RcWeak<String>>::SHAPE;
        let weak_def = weak_shape
            .def
            .into_smart_pointer()
            .expect("RcWeak<T> should have a smart pointer definition");

        // 1. Create the first Rc (rc1)
        let rc1_uninit_ptr = rc_shape.allocate()?;
        let new_into_fn = rc_def.vtable.new_into_fn.unwrap();
        let mut value = String::from("example");
        let rc1_ptr = unsafe { new_into_fn(rc1_uninit_ptr, PtrMut::new(&raw mut value)) };
        core::mem::forget(value); // Value now owned by rc1

        // 2. Downgrade rc1 to create a weak pointer (weak1)
        let weak1_uninit_ptr = weak_shape.allocate()?;
        let downgrade_into_fn = rc_def.vtable.downgrade_into_fn.unwrap();
        // SAFETY: rc1_ptr points to a valid Rc, weak1_uninit_ptr is allocated for a Weak
        let weak1_ptr = unsafe { downgrade_into_fn(rc1_ptr, weak1_uninit_ptr) };

        // 3. Upgrade weak1 to create a second Rc (rc2)
        let rc2_uninit_ptr = rc_shape.allocate()?;
        let upgrade_into_fn = weak_def.vtable.upgrade_into_fn.unwrap();
        // SAFETY: weak1_ptr points to a valid Weak, rc2_uninit_ptr is allocated for an Rc.
        // Upgrade should succeed as rc1 still exists.
        let rc2_ptr = unsafe { upgrade_into_fn(weak1_ptr, rc2_uninit_ptr) }
            .expect("Upgrade should succeed while original Rc exists");

        // Check the content of the upgraded Rc
        let borrow_fn = rc_def.vtable.borrow_fn.unwrap();
        // SAFETY: rc2_ptr points to a valid Rc<String>
        let borrowed_ptr = unsafe { borrow_fn(rc2_ptr.as_const()) };
        // SAFETY: borrowed_ptr points to a valid String
        assert_eq!(unsafe { borrowed_ptr.get::<String>() }, "example");

        // 4. Drop everything and free memory
        let rc_drop_fn = (rc_shape.vtable.drop_in_place)().unwrap();
        let weak_drop_fn = (weak_shape.vtable.drop_in_place)().unwrap();

        unsafe {
            // Drop Rcs
            rc_drop_fn(rc1_ptr);
            rc_shape.deallocate_mut(rc1_ptr)?;
            rc_drop_fn(rc2_ptr);
            rc_shape.deallocate_mut(rc2_ptr)?;

            // Drop Weak
            weak_drop_fn(weak1_ptr);
            weak_shape.deallocate_mut(weak1_ptr)?;
        }

        Ok(())
    }

    #[test]
    fn test_rc_vtable_3_downgrade_drop_try_upgrade() -> eyre::Result<()> {
        facet_testhelpers::setup();

        let rc_shape = <Rc<String>>::SHAPE;
        let rc_def = rc_shape
            .def
            .into_smart_pointer()
            .expect("Rc<T> should have a smart pointer definition");

        let weak_shape = <RcWeak<String>>::SHAPE;
        let weak_def = weak_shape
            .def
            .into_smart_pointer()
            .expect("RcWeak<T> should have a smart pointer definition");

        // 1. Create the strong Rc (rc1)
        let rc1_uninit_ptr = rc_shape.allocate()?;
        let new_into_fn = rc_def.vtable.new_into_fn.unwrap();
        let mut value = String::from("example");
        let rc1_ptr = unsafe { new_into_fn(rc1_uninit_ptr, PtrMut::new(&raw mut value)) };
        core::mem::forget(value);

        // 2. Downgrade rc1 to create a weak pointer (weak1)
        let weak1_uninit_ptr = weak_shape.allocate()?;
        let downgrade_into_fn = rc_def.vtable.downgrade_into_fn.unwrap();
        // SAFETY: rc1_ptr is valid, weak1_uninit_ptr is allocated for Weak
        let weak1_ptr = unsafe { downgrade_into_fn(rc1_ptr, weak1_uninit_ptr) };

        // 3. Drop and free the strong pointer (rc1)
        let rc_drop_fn = (rc_shape.vtable.drop_in_place)().unwrap();
        unsafe {
            rc_drop_fn(rc1_ptr);
            rc_shape.deallocate_mut(rc1_ptr)?;
        }

        // 4. Attempt to upgrade the weak pointer (weak1)
        let upgrade_into_fn = weak_def.vtable.upgrade_into_fn.unwrap();
        let rc2_uninit_ptr = rc_shape.allocate()?;
        // SAFETY: weak1_ptr is valid (though points to dropped data), rc2_uninit_ptr is allocated for Rc
        let upgrade_result = unsafe { upgrade_into_fn(weak1_ptr, rc2_uninit_ptr) };

        // Assert that the upgrade failed
        assert!(
            upgrade_result.is_none(),
            "Upgrade should fail after the strong Rc is dropped"
        );

        // 5. Clean up: Deallocate the memory intended for the failed upgrade and drop/deallocate the weak pointer
        let weak_drop_fn = (weak_shape.vtable.drop_in_place)().unwrap();
        unsafe {
            // Deallocate the *uninitialized* memory allocated for the failed upgrade attempt
            rc_shape.deallocate_uninit(rc2_uninit_ptr)?;

            // Drop and deallocate the weak pointer
            weak_drop_fn(weak1_ptr);
            weak_shape.deallocate_mut(weak1_ptr)?;
        }

        Ok(())
    }
}

1	use crate::{
2	Def, Facet, KnownSmartPointer, PtrConst, PtrMut, PtrUninit, Shape, SmartPointerDef,
3	SmartPointerFlags, SmartPointerVTable, TryBorrowInnerError, TryFromError, TryIntoInnerError,
4	Type, UserType, ValueVTable, value_vtable,
5	};
6
7	unsafe impl<'a, T: Facet<'a>> Facet<'a> for alloc::rc::Rc<T> {
8	const VTABLE: &'static ValueVTable = &const {
9	// Define the functions for transparent conversion between Rc<T> and T
10	unsafe fn try_from<'a, 'shape, 'src, 'dst, T: Facet<'a>>(	×
11	src_ptr: PtrConst<'src>,	×
12	src_shape: &'shape Shape<'shape>,	×
13	dst: PtrUninit<'dst>,	×
14	) -> Result<PtrMut<'dst>, TryFromError<'shape>> {	×
15	if src_shape.id != T::SHAPE.id {	×
16	return Err(TryFromError::UnsupportedSourceShape {	×
17	src_shape,	×
18	expected: &[T::SHAPE],	×
19	});	×
20	}	×
21	let t = unsafe { src_ptr.read::<T>() };	×
22	let rc = alloc::rc::Rc::new(t);	×
23	Ok(unsafe { dst.put(rc) })	×
24	}	×
25
26	unsafe fn try_into_inner<'a, 'src, 'dst, T: Facet<'a>>(	×
27	src_ptr: PtrMut<'src>,	×
28	dst: PtrUninit<'dst>,	×
29	) -> Result<PtrMut<'dst>, TryIntoInnerError> {	×
30	let rc = unsafe { src_ptr.get::<alloc::rc::Rc<T>>() };	×
31	match alloc::rc::Rc::try_unwrap(rc.clone()) {	×
32	Ok(t) => Ok(unsafe { dst.put(t) }),	×
33	Err(_) => Err(TryIntoInnerError::Unavailable),	×
34	}
35	}	×
36
37	unsafe fn try_borrow_inner<'a, 'src, T: Facet<'a>>(	×
38	src_ptr: PtrConst<'src>,	×
39	) -> Result<PtrConst<'src>, TryBorrowInnerError> {	×
40	let rc = unsafe { src_ptr.get::<alloc::rc::Rc<T>>() };	×
41	Ok(PtrConst::new(&**rc))	×
42	}	×
43
44	let mut vtable = value_vtable!(alloc::rc::Rc<T>, \|f, opts\| {	×
45	write!(f, "Rc")?;	×
46	if let Some(opts) = opts.for_children() {	×
47	write!(f, "<")?;	×
48	(T::SHAPE.vtable.type_name)(f, opts)?;	×
49	write!(f, ">")?;	×
50	} else {
51	write!(f, "<…>")?;	×
52	}
53	Ok(())	×
54	});	×
NEW 55	vtable.try_from = \|\| Some(try_from::<T>);	×
NEW 56	vtable.try_into_inner = \|\| Some(try_into_inner::<T>);	×
NEW 57	vtable.try_borrow_inner = \|\| Some(try_borrow_inner::<T>);	×
58	vtable
59	};
60
61	const SHAPE: &'static crate::Shape<'static> = &const {
62	// Function to return inner type's shape
63	fn inner_shape<'a, T: Facet<'a>>() -> &'static Shape<'static> {	×
64	T::SHAPE	×
65	}	×
66
67	crate::Shape::builder_for_sized::<Self>()
68	.type_params(&[crate::TypeParam {
69	name: "T",
70	shape: \|\| T::SHAPE,
71	}])
72	.ty(Type::User(UserType::Opaque))
73	.def(Def::SmartPointer(
74	SmartPointerDef::builder()
75	.pointee(\|\| T::SHAPE)
76	.flags(SmartPointerFlags::EMPTY)
77	.known(KnownSmartPointer::Rc)
78	.weak(\|\| <alloc::rc::Weak<T> as Facet>::SHAPE)
79	.vtable(
80	&const {
81	SmartPointerVTable::builder()
82	.borrow_fn(\|this\| {	2✔
83	let ptr = Self::as_ptr(unsafe { this.get() });	2✔
84	PtrConst::new(ptr)	2✔
85	})	2✔
86	.new_into_fn(\|this, ptr\| {	3✔
87	let t = unsafe { ptr.read::<T>() };	3✔
88	let rc = alloc::rc::Rc::new(t);	3✔
89	unsafe { this.put(rc) }	3✔
90	})	3✔
91	.downgrade_into_fn(\|strong, weak\| unsafe {
92	weak.put(alloc::rc::Rc::downgrade(strong.get::<Self>()))	2✔
93	})	2✔
94	.build()
95	},
96	)
97	.build(),
98	))
99	.inner(inner_shape::<T>)
100	.build()
101	};
102	}
103
104	unsafe impl<'a, T: Facet<'a>> Facet<'a> for alloc::rc::Weak<T> {
105	const VTABLE: &'static ValueVTable = &const {
106	value_vtable!(alloc::rc::Weak<T>, \|f, opts\| {	×
107	write!(f, "Weak")?;	×
108	if let Some(opts) = opts.for_children() {	×
109	write!(f, "<")?;	×
110	(T::SHAPE.vtable.type_name)(f, opts)?;	×
111	write!(f, ">")?;	×
112	} else {
113	write!(f, "<…>")?;	×
114	}
115	Ok(())	×
116	})	×
117	};
118
119	const SHAPE: &'static crate::Shape<'static> = &const {
120	// Function to return inner type's shape
121	fn inner_shape<'a, T: Facet<'a>>() -> &'static Shape<'static> {	×
122	T::SHAPE	×
123	}	×
124
125	crate::Shape::builder_for_sized::<Self>()
126	.type_params(&[crate::TypeParam {
127	name: "T",
128	shape: \|\| T::SHAPE,
129	}])
130	.ty(Type::User(UserType::Opaque))
131	.def(Def::SmartPointer(
132	SmartPointerDef::builder()
133	.pointee(\|\| T::SHAPE)
134	.flags(SmartPointerFlags::WEAK)
135	.known(KnownSmartPointer::RcWeak)
136	.strong(\|\| <alloc::rc::Rc<T> as Facet>::SHAPE)
137	.vtable(
138	&const {
139	SmartPointerVTable::builder()
140	.upgrade_into_fn(\|weak, strong\| unsafe {
141	Some(strong.put(weak.get::<Self>().upgrade()?))	2✔
142	})	2✔
143	.build()
144	},
145	)
146	.build(),
147	))
148	.inner(inner_shape::<T>)
149	.build()
150	};
151	}
152
153	#[cfg(test)]
154	mod tests {
155	use alloc::rc::{Rc, Weak as RcWeak};
156	use alloc::string::String;
157
158	use super::*;
159
160	#[test]
161	fn test_rc_type_params() {	1✔
162	let [type_param_1] = <Rc<i32>>::SHAPE.type_params else {	1✔
163	panic!("Rc<T> should only have 1 type param")	×
164	};
165	assert_eq!(type_param_1.shape(), i32::SHAPE);	1✔
166	}	1✔
167
168	#[test]
169	fn test_rc_vtable_1_new_borrow_drop() -> eyre::Result<()> {	1✔
170	facet_testhelpers::setup();	1✔
171
172	let rc_shape = <Rc<String>>::SHAPE;	1✔
173	let rc_def = rc_shape	1✔
174	.def	1✔
175	.into_smart_pointer()	1✔
176	.expect("Rc<T> should have a smart pointer definition");	1✔
177
178	// Allocate memory for the Rc
179	let rc_uninit_ptr = rc_shape.allocate()?;	1✔
180
181	// Get the function pointer for creating a new Rc from a value
182	let new_into_fn = rc_def	1✔
183	.vtable	1✔
184	.new_into_fn	1✔
185	.expect("Rc<T> should have new_into_fn");	1✔
186
187	// Create the value and initialize the Rc
188	let mut value = String::from("example");	1✔
189	let rc_ptr = unsafe { new_into_fn(rc_uninit_ptr, PtrMut::new(&raw mut value)) };	1✔
190	// The value now belongs to the Rc, prevent its drop
191	core::mem::forget(value);	1✔
192
193	// Get the function pointer for borrowing the inner value
194	let borrow_fn = rc_def	1✔
195	.vtable	1✔
196	.borrow_fn	1✔
197	.expect("Rc<T> should have borrow_fn");	1✔
198
199	// Borrow the inner value and check it
200	let borrowed_ptr = unsafe { borrow_fn(rc_ptr.as_const()) };	1✔
201	// SAFETY: borrowed_ptr points to a valid String within the Rc
202	assert_eq!(unsafe { borrowed_ptr.get::<String>() }, "example");	1✔
203
204	// Get the function pointer for dropping the Rc
205	let drop_fn = (rc_shape.vtable.drop_in_place)().expect("Rc<T> should have drop_in_place");	1✔
206
207	// Drop the Rc in place
208	// SAFETY: rc_ptr points to a valid Rc<String>
209	unsafe { drop_fn(rc_ptr) };	1✔
210
211	// Deallocate the memory
212	// SAFETY: rc_ptr was allocated by rc_shape and is now dropped (but memory is still valid)
213	unsafe { rc_shape.deallocate_mut(rc_ptr)? };	1✔
214
215	Ok(())	1✔
216	}	1✔
217
218	#[test]
219	fn test_rc_vtable_2_downgrade_upgrade_drop() -> eyre::Result<()> {	1✔
220	facet_testhelpers::setup();	1✔
221
222	let rc_shape = <Rc<String>>::SHAPE;	1✔
223	let rc_def = rc_shape	1✔
224	.def	1✔
225	.into_smart_pointer()	1✔
226	.expect("Rc<T> should have a smart pointer definition");	1✔
227
228	let weak_shape = <RcWeak<String>>::SHAPE;	1✔
229	let weak_def = weak_shape	1✔
230	.def	1✔
231	.into_smart_pointer()	1✔
232	.expect("RcWeak<T> should have a smart pointer definition");	1✔
233
234	// 1. Create the first Rc (rc1)
235	let rc1_uninit_ptr = rc_shape.allocate()?;	1✔
236	let new_into_fn = rc_def.vtable.new_into_fn.unwrap();	1✔
237	let mut value = String::from("example");	1✔
238	let rc1_ptr = unsafe { new_into_fn(rc1_uninit_ptr, PtrMut::new(&raw mut value)) };	1✔
239	core::mem::forget(value); // Value now owned by rc1	1✔
240
241	// 2. Downgrade rc1 to create a weak pointer (weak1)
242	let weak1_uninit_ptr = weak_shape.allocate()?;	1✔
243	let downgrade_into_fn = rc_def.vtable.downgrade_into_fn.unwrap();	1✔
244	// SAFETY: rc1_ptr points to a valid Rc, weak1_uninit_ptr is allocated for a Weak
245	let weak1_ptr = unsafe { downgrade_into_fn(rc1_ptr, weak1_uninit_ptr) };	1✔
246
247	// 3. Upgrade weak1 to create a second Rc (rc2)
248	let rc2_uninit_ptr = rc_shape.allocate()?;	1✔
249	let upgrade_into_fn = weak_def.vtable.upgrade_into_fn.unwrap();	1✔
250	// SAFETY: weak1_ptr points to a valid Weak, rc2_uninit_ptr is allocated for an Rc.
251	// Upgrade should succeed as rc1 still exists.
252	let rc2_ptr = unsafe { upgrade_into_fn(weak1_ptr, rc2_uninit_ptr) }	1✔
253	.expect("Upgrade should succeed while original Rc exists");	1✔
254
255	// Check the content of the upgraded Rc
256	let borrow_fn = rc_def.vtable.borrow_fn.unwrap();	1✔
257	// SAFETY: rc2_ptr points to a valid Rc<String>
258	let borrowed_ptr = unsafe { borrow_fn(rc2_ptr.as_const()) };	1✔
259	// SAFETY: borrowed_ptr points to a valid String
260	assert_eq!(unsafe { borrowed_ptr.get::<String>() }, "example");	1✔
261
262	// 4. Drop everything and free memory
263	let rc_drop_fn = (rc_shape.vtable.drop_in_place)().unwrap();	1✔
264	let weak_drop_fn = (weak_shape.vtable.drop_in_place)().unwrap();	1✔
265
266	unsafe {
267	// Drop Rcs
268	rc_drop_fn(rc1_ptr);	1✔
269	rc_shape.deallocate_mut(rc1_ptr)?;	1✔
270	rc_drop_fn(rc2_ptr);	1✔
271	rc_shape.deallocate_mut(rc2_ptr)?;	1✔
272
273	// Drop Weak
274	weak_drop_fn(weak1_ptr);	1✔
275	weak_shape.deallocate_mut(weak1_ptr)?;	1✔
276	}
277
278	Ok(())	1✔
279	}	1✔
280
281	#[test]
282	fn test_rc_vtable_3_downgrade_drop_try_upgrade() -> eyre::Result<()> {	1✔
283	facet_testhelpers::setup();	1✔
284
285	let rc_shape = <Rc<String>>::SHAPE;	1✔
286	let rc_def = rc_shape	1✔
287	.def	1✔
288	.into_smart_pointer()	1✔
289	.expect("Rc<T> should have a smart pointer definition");	1✔
290
291	let weak_shape = <RcWeak<String>>::SHAPE;	1✔
292	let weak_def = weak_shape	1✔
293	.def	1✔
294	.into_smart_pointer()	1✔
295	.expect("RcWeak<T> should have a smart pointer definition");	1✔
296
297	// 1. Create the strong Rc (rc1)
298	let rc1_uninit_ptr = rc_shape.allocate()?;	1✔
299	let new_into_fn = rc_def.vtable.new_into_fn.unwrap();	1✔
300	let mut value = String::from("example");	1✔
301	let rc1_ptr = unsafe { new_into_fn(rc1_uninit_ptr, PtrMut::new(&raw mut value)) };	1✔
302	core::mem::forget(value);	1✔
303
304	// 2. Downgrade rc1 to create a weak pointer (weak1)
305	let weak1_uninit_ptr = weak_shape.allocate()?;	1✔
306	let downgrade_into_fn = rc_def.vtable.downgrade_into_fn.unwrap();	1✔
307	// SAFETY: rc1_ptr is valid, weak1_uninit_ptr is allocated for Weak
308	let weak1_ptr = unsafe { downgrade_into_fn(rc1_ptr, weak1_uninit_ptr) };	1✔
309
310	// 3. Drop and free the strong pointer (rc1)
311	let rc_drop_fn = (rc_shape.vtable.drop_in_place)().unwrap();	1✔
312	unsafe {
313	rc_drop_fn(rc1_ptr);	1✔
314	rc_shape.deallocate_mut(rc1_ptr)?;	1✔
315	}
316
317	// 4. Attempt to upgrade the weak pointer (weak1)
318	let upgrade_into_fn = weak_def.vtable.upgrade_into_fn.unwrap();	1✔
319	let rc2_uninit_ptr = rc_shape.allocate()?;	1✔
320	// SAFETY: weak1_ptr is valid (though points to dropped data), rc2_uninit_ptr is allocated for Rc
321	let upgrade_result = unsafe { upgrade_into_fn(weak1_ptr, rc2_uninit_ptr) };	1✔
322
323	// Assert that the upgrade failed
324	assert!(	1✔
325	upgrade_result.is_none(),	1✔
326	"Upgrade should fail after the strong Rc is dropped"	×
327	);
328
329	// 5. Clean up: Deallocate the memory intended for the failed upgrade and drop/deallocate the weak pointer
330	let weak_drop_fn = (weak_shape.vtable.drop_in_place)().unwrap();	1✔
331	unsafe {
332	// Deallocate the uninitialized memory allocated for the failed upgrade attempt
333	rc_shape.deallocate_uninit(rc2_uninit_ptr)?;	1✔
334
335	// Drop and deallocate the weak pointer
336	weak_drop_fn(weak1_ptr);	1✔
337	weak_shape.deallocate_mut(weak1_ptr)?;	1✔
338	}
339
340	Ok(())	1✔
341	}	1✔
342	}

facet-rs / facet / 15200164445

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