Sample
anyhow 1.0.104: Convert anyhow::Error to Box<dyn StdError> via into_boxed_dyn_error vs reallocate_into_boxed_dyn_error_without_backtrace to retain downcastability, convert from boxed errors with Error::from_boxed, and mutate root errors through context layers via downcast_mut
Verified sample for cargo anyhow 1.0.104: Convert anyhow::Error to Box<dyn StdError> via into_boxed_dyn_error vs…
sha256:175897b84668b354a5c39ba16574961f62a504460d7259ed94746eae6b9bf866
This network offers one thing: a sample that builds. It ran the sample in a sandbox and kept the signed receipt. It grades nothing and warrants nothing — whether the same code builds where you are is not something it measured.
How many distinct signing keys filed a passing contract receipt. One is the author alone; more than one means somebody else built it too. A key is self-generated with nothing registered behind it, so it counts keys, not people.
MIT-0
Execution evidence
The declared environment and the signed runs are kept apart, so you can see exactly what this sample ran and where.
- Evidence basis
- Signed contract pass
- Verification receipts
- 2
- Signing keys that built it
- 2
Declared environment
rust linux x64 rust rust cargo
Verification-run environments
| Environment | Contract | Stages | Run |
|---|---|---|---|
| rust 1 · linux alpine/x64 · docker ed25519:d91480838ac982c9 | PASS | compile:SKIPPED · contract:PASS · load:PASS · resolve:PASS CONTAINER_RUN · cargo@1 |
2026-08-16 |
| rust 1 · linux alpine/x64 · docker ed25519:2175b912ea1c23b1 | PASS | compile:SKIPPED · contract:PASS · load:PASS · resolve:PASS CONTAINER_RUN · cargo@1 |
2026-08-18 |
Case
HOW- Goal
- Convert anyhow::Error to Box<dyn StdError> via into_boxed_dyn_error vs reallocate_into_boxed_dyn_error_without_backtrace to retain downcastability, convert from boxed errors with Error::from_boxed, and mutate root errors through context layers via downcast_mut
- Packages
- Symbols
-
- anyhow::Error::into_boxed_dyn_error
- anyhow::Error::reallocate_into_boxed_dyn_error_without_backtrace
- anyhow::Error::from_boxed
- anyhow::Error::downcast_mut
- anyhow::Error::downcast_ref
- Environment
- rust
- Created
- 2026-08-16T07:54:49Z
Contract
- assert into_boxed_dyn_error performs a zero-realloc pointer cast to Box<dyn StdError> whose Display matches but downcast_ref to the inner concrete type returns None
- assert reallocate_into_boxed_dyn_error_without_backtrace creates a new Box<dyn StdError> enabling downcast_ref and downcast to the concrete error type
- assert reallocate_into_boxed_dyn_error_without_backtrace on a context-wrapped error preserves the outermost Display and provides the full source chain
- assert Error::from_boxed converts a Box<dyn StdError> into anyhow::Error where direct downcast to the concrete type returns None but downcasting to Box<dyn StdError> recovers the boxed trait object
- assert downcast_mut traverses through multiple context layers allowing in-place mutation of the root error that persists across subsequent downcast_ref queries
Files
- Cargo.lock
- Cargo.toml
- NOTES.md
- csx.json
- src/lib.rs