14e72e7ffa
Previous Stacked Borrows diagnostics were missing a lot of information about the state of the interpreter, and it was difficult to add additional state because it was threaded through all the intervening function signatures. This change factors a lot of the arguments which used to be passed individually to many stacked borrows functions into a single `DiagnosticCx`, which is built in `Stacks::for_each`, and since it wraps a handle to `AllocHistory`, we can now handle more nuanced things like heterogeneous borrow of `!Freeze` types.
23 lines
911 B
Rust
23 lines
911 B
Rust
// Creating a shared reference does not leak the data to raw pointers,
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// not even when interior mutability is involved.
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use std::cell::Cell;
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use std::ptr;
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fn main() {
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unsafe {
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let x = &mut Cell::new(0);
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let raw = x as *mut Cell<i32>;
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let x = &mut *raw;
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let _shr = &*x;
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// The state here is interesting because the top of the stack is [Unique, SharedReadWrite],
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// just like if we had done `x as *mut _`.
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// If we said that reading from a lower item is fine if the top item is `SharedReadWrite`
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// (one way to maybe preserve a stack discipline), then we could now read from `raw`
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// without invalidating `x`. That would be bad! It would mean that creating `shr`
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// leaked `x` to `raw`.
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let _val = ptr::read(raw);
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let _val = *x.get_mut(); //~ ERROR: /retag .* tag does not exist in the borrow stack/
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}
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}
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