64 lines
2.2 KiB
Rust
64 lines
2.2 KiB
Rust
// compile-flags: -Zmiri-tag-raw-pointers
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fn empty() -> &'static str {
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""
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}
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fn hello() -> &'static str {
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"Hello, world!"
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}
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fn hello_bytes() -> &'static [u8; 13] {
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b"Hello, world!"
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}
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fn hello_bytes_fat() -> &'static [u8] {
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b"Hello, world!"
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}
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fn fat_pointer_on_32_bit() {
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Some(5).expect("foo");
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}
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fn str_indexing() {
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let mut x = "Hello".to_string();
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let _v = &mut x[..3]; // Test IndexMut on String.
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}
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fn unique_aliasing() {
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// This is a regression test for the aliasing rules of a `Unique<T>` pointer.
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// At the time of writing this test case, Miri does not treat `Unique<T>`
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// pointers as a special case, these are treated like any other raw pointer.
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// However, there are existing Github issues which may lead to `Unique<T>`
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// becoming a special case through asserting unique ownership over the pointee:
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// - https://github.com/rust-lang/unsafe-code-guidelines/issues/258
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// - https://github.com/rust-lang/unsafe-code-guidelines/issues/262
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// Below, the calls to `String::remove` and `String::insert[_str]` follow
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// code paths that would trigger undefined behavior in case `Unique<T>`
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// would ever assert semantic ownership over the pointee. Internally,
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// these methods call `self.vec.as_ptr()` and `self.vec.as_mut_ptr()` on
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// the vector of bytes that are backing the `String`. That `Vec<u8>` holds a
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// `Unique<u8>` internally. The second call to `Vec::as_mut_ptr(&mut self)`
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// would then invalidate the pointers derived from `Vec::as_ptr(&self)`.
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// Note that as long as `Unique<T>` is treated like any other raw pointer,
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// this test case should pass. It is merely here as a canary test for
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// potential future undefined behavior.
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let mut x = String::from("Hello");
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assert_eq!(x.remove(0), 'H');
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x.insert(0, 'H');
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assert_eq!(x, "Hello");
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x.insert_str(x.len(), ", world!");
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assert_eq!(x, "Hello, world!");
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}
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fn main() {
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assert_eq!(empty(), "");
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assert_eq!(hello(), "Hello, world!");
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assert_eq!(hello_bytes(), b"Hello, world!");
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assert_eq!(hello_bytes_fat(), b"Hello, world!");
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fat_pointer_on_32_bit(); // Should run without crashing.
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str_indexing();
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unique_aliasing();
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}
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