aa589d3dc7
Save a created event for zero-size reborrows
Currently, we don't save a created event for zero-sized reborrows. Attempting to use something from a zero-sized reborrow is surprisingly common, for example on `minimal-lexical==0.2.1` we previously just emit this:
```
Undefined Behavior: attempting a write access using <187021> at alloc72933[0x0], but that tag does not exist in the borrow stack for this location
--> /root/rust/library/core/src/ptr/mod.rs:1287:9
|
1287 | copy_nonoverlapping(&src as *const T, dst, 1);
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
| |
| attempting a write access using <187021> at alloc72933[0x0], but that tag does not exist in the borrow stack for this location
| this error occurs as part of an access at alloc72933[0x0..0x8]
|
= help: this indicates a potential bug in the program: it performed an invalid operation, but the 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
= note: inside `std::ptr::write::<u64>` at /root/rust/library/core/src/ptr/mod.rs:1287:9
note: inside `minimal_lexical::stackvec::StackVec::push_unchecked` at /root/build/src/stackvec.rs:82:13
--> /root/build/src/stackvec.rs:82:13
|
82 | ptr::write(self.as_mut_ptr().add(self.len()), value);
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
... backtrace continues...
```
Which leaves us with the question "where did we make this pointer?" because for every other diagnostic you get a "was created by" note, so I suspect people might be tempted to think there is a Miri bug here. I certainly was.
---
This code duplication is so awful, I'm going to take a look at cleaning it up later. The fact that `ptr_get_alloc_id` can fail in this situation makes things annoying.
|
||
|---|---|---|
| .. | ||
| bin | ||
| helpers | ||
| shims | ||
| stacked_borrows | ||
| data_race.rs | ||
| diagnostics.rs | ||
| eval.rs | ||
| helpers.rs | ||
| intptrcast.rs | ||
| lib.rs | ||
| machine.rs | ||
| mono_hash_map.rs | ||
| operator.rs | ||
| range_map.rs | ||
| stacked_borrows.rs | ||
| sync.rs | ||
| thread.rs | ||
| vector_clock.rs | ||