Skip to content

Challenge 25: Verify safety of VecDeque #564

New issue

Have a question about this project? Sign up for a free GitHub account to open an issue and contact its maintainers and the community.

Sign up for GitHub

By clicking “Sign up for GitHub”, you agree to our terms of service and privacy statement. We’ll occasionally send you account related emails.

Already on GitHub? Sign in to your account

Open
Samuelsills wants to merge 1 commit into
base: main
Choose a base branch
from
+690 −2
Open

Challenge 25: Verify safety of VecDeque #564

Show file tree
Hide file tree
Changes from all commits
Commits
Show all changes
1 commit
Select commit
File filter

Filter by extension

Filter by extension
Conversations
Failed to load comments.
Loading
Jump to
Jump to file
Failed to load files.
Loading
Diff view
Diff view
61 changes: 61 additions & 0 deletions doc/src/challenges/0025-vecdeque.md
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -87,3 +87,64 @@ All proofs must automatically ensure the absence of the following undefined beha

Note: All solutions to verification challenges need to satisfy the criteria established in the [challenge book](../general-rules.md)
in addition to the ones listed above.

## Verification Summary

All 13 Part A unsafe functions and all 30 Part B safe abstractions have been verified using Kani.

### Part A: Safety Contracts (`#[requires]`/`#[ensures]` with `#[kani::proof_for_contract]`)

All unsafe functions have `#[requires]` contracts formalizing their safety preconditions, verified by `#[kani::proof_for_contract]` harnesses:

| Function | Contract | Harness |
|----------|----------|---------|
| `push_unchecked` | `self.len < self.capacity()` | `check_push_unchecked` |
| `buffer_read` | `off < self.capacity()` | `check_buffer_read` |
| `buffer_write` | `off < self.capacity()` | `check_buffer_write` |
| `buffer_range` | `range.start <= range.end && range.end <= self.capacity()` | `check_buffer_range` |
| `copy` | `len <= cap && src <= cap - len && dst <= cap - len` | `check_copy` |
| `copy_nonoverlapping` | Same as `copy` + non-overlap | `check_copy_nonoverlapping` |
| `wrap_copy` | `min(diff, cap - diff) + len <= cap` | `check_wrap_copy` |
| `copy_slice` | `src.len() <= cap && dst < cap` | `check_copy_slice` |
| `write_iter` | `dst < self.capacity()` | `check_write_iter` |
| `write_iter_wrapping` | `dst < cap && len <= cap` | `check_write_iter_wrapping` |
| `handle_capacity_increase` | `old_cap <= cap && len <= old_cap` | `check_handle_capacity_increase` |
| `from_contiguous_raw_parts_in` | `init.start <= init.end <= capacity` | `check_from_contiguous_raw_parts_in` |
| `abort_shrink` | `target_cap <= cap && len <= target_cap && old_head < cap` | `check_abort_shrink` |
| `rotate_left_inner` | `mid <= self.len() / 2` | `check_rotate_left_inner` |
| `rotate_right_inner` | `k <= self.len() / 2` | `check_rotate_right_inner` |

Copy link

Copilot AI Mar 31, 2026

Choose a reason for hiding this comment

The reason will be displayed to describe this comment to others. Learn more.

The verification summary claims "All 13 Part A unsafe functions" were verified, but the table lists 15 functions (it includes rotate_left_inner and rotate_right_inner). Please reconcile the counts/text so the summary matches what’s actually covered.

Suggested change
Note: The core Part A includes 13 unsafe functions. The two internal helpers
`rotate_left_inner` and `rotate_right_inner` are listed here and verified as
well, but are not counted among those 13 Part A unsafe functions.

Copilot uses AI. Check for mistakes.
### Part B: UB Absence Proofs (`#[kani::proof]`)

All safe abstractions verified with `#[kani::proof]` harnesses proving no undefined behavior:

| Function | Harness |
|----------|---------|
| `get` | `check_get` |
| `get_mut` | `check_get_mut` |
| `swap` | `check_swap` |
| `reserve_exact` | `check_reserve_exact` |
| `reserve` | `check_reserve` |
| `try_reserve_exact` | `check_try_reserve_exact` |
| `try_reserve` | `check_try_reserve` |
| `shrink_to` | `check_shrink_to` |
| `truncate` | `check_truncate` |
| `as_slices` | `check_as_slices` |
| `as_mut_slices` | `check_as_mut_slices` |
| `range` | `check_range` |
| `range_mut` | `check_range_mut` |
| `drain` | `check_drain` |
| `pop_front` | `check_pop_front` |
| `pop_back` | `check_pop_back` |
| `push_front` | `check_push_front` |
| `push_back` | `check_push_back` |
| `insert` | `check_insert` |
| `remove` | `check_remove` |
| `split_off` | `check_split_off` |
| `append` | `check_append` |
| `retain_mut` | `check_retain_mut` |
| `grow` | `check_grow` |
| `resize_with` | `check_resize_with` |
| `make_contiguous` | `check_make_contiguous` |
| `rotate_left` | `check_rotate_left` |
| `rotate_right` | `check_rotate_right` |
Loading
Loading