reading-list: add "Box Is a Unique Type"

src/reading-list/2024a.md

@@ -48,6 +48,79 @@
 * [Benchmarking rust compilation speedups and slowdowns from sccache and -Zthreads](https://neosmart.net/blog/benchmarking-rust-compilation-speedups-and-slowdowns-from-sccache-and-zthreads/)：
   由于 WSL1 的 IO 性能较差，在那使用 sccache 可能并不会加速增量构建，反而会拖慢编译
 
+# unsafe
+
+* [Box Is a Unique Type](https://nilstrieb.dev/blog/posts/box-is-a-unique-type/) by nilstrieb
+  * 用 Miri 分析/解释 UB 的示例；Box 在 noalias 语义上具有分歧 —— UB 与 Rust 语义紧密联系
+  * [Too Many Linked Lists: Attempting To Understand Stacked Borrows](https://rust-unofficial.github.io/too-many-lists/fifth-stacked-borrows.html)
+  * [UCG#326: What are the uniqueness guarantees of Box and Vec?](https://github.com/rust-lang/unsafe-code-guidelines/issues/326)
+  * [The Unsafe Chronicles: Exhibit A: Aliasing Boxes](https://www.youtube.com/watch?v=EY7Wi9fV5bk&ab_channel=JonGjengset) by Jonhoo
+
+```rust
+use aliasable::boxed::AliasableBox;
+
+fn main() {
+    let b = Box::new(0);
+    let b = AliasableBox::from_unique(b);
+    let ptr: *const u8 = &*b;
+
+    takes_box_and_ptr_to_it(b, ptr);
+}
+
+fn takes_box_and_ptr_to_it(mut b: AliasableBox<u8>, ptr: *const u8) { // no UB
+    let value = unsafe { *ptr };
+    *b = 5;
+    let value2 = unsafe { *b };
+    assert_ne!(value, value2);
+}
+```
+
+```rust
+fn main() {
+    let b = Box::new(0);
+    let ptr: *const u8 = &*b;
+
+    takes_box_and_ptr_to_it(b, ptr);
+}
+
+fn takes_box_and_ptr_to_it(mut b: Box<u8>, ptr: *const u8) { // UB
+    let value = unsafe { *ptr };
+    *b = 5;
+    let value2 = unsafe { *b };
+    assert_ne!(value, value2);
+}
+
+error: Undefined Behavior: attempting a read access using <2248> at alloc1032[0x0], but that tag does not exist in the borrow stack for this location
+  --> src/main.rs:13:26
+   |
+13 |     let value = unsafe { *ptr };
+   |                          ^^^^
+   |                          |
+   |                          attempting a read access using <2248> at alloc1032[0x0], but that tag does not exist in the borrow stack for this location
+   |                          this error occurs as part of an access at alloc1032[0x0..0x1]
+   |
+   = help: this indicates a potential bug in the program: it performed an invalid operation, but the Stacked Borrows rules it violated are still experimental
+   = help: see https://github.com/rust-lang/unsafe-code-guidelines/blob/master/wip/stacked-borrows.md for further information
+help: <2248> was created by a SharedReadOnly retag at offsets [0x0..0x1]
+  --> src/main.rs:6:26
+   |
+6  |     let ptr: *const u8 = &*b;
+   |                          ^^^
+help: <2248> was later invalidated at offsets [0x0..0x1] by a Unique retag
+  --> src/main.rs:8:29
+   |
+8  |     takes_box_and_ptr_to_it(b, ptr);
+   |                             ^
+   = note: BACKTRACE (of the first span):
+   = note: inside `takes_box_and_ptr_to_it` at src/main.rs:13:26: 13:30
+note: inside `main`
+  --> src/main.rs:8:5
+   |
+8  |     takes_box_and_ptr_to_it(b, ptr);
+   |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+```
+
+
 # TODO
 
 <https://blog.shrirambalaji.com/posts/resolving-rust-symbols/>：解析 ELF 中的 Rust 符号