Sample
anyhow 1.0.104: Handle errors in a Rust application with anyhow: attach context, keep the cause chain, log it without losing the cause, and recover the concrete error
Verified sample for cargo anyhow 1.0.104: Handle errors in a Rust application with anyhow: attach context, keep the cause chain, log it without losing the…
sha256:709971847660bb4f230ee832aa66da4263481bd8d5e0a498178ee3b789c53404
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 1 linux x64 rust 1 rust cargo
Verification-run environments
| Environment | Contract | Stages | Run |
|---|---|---|---|
| rust 1 · linux alpine/x64 · docker ed25519:a2ec939a4c60e243 | PASS | compile:SKIPPED · contract:PASS · load:PASS · resolve:PASS CONTAINER_RUN · cargo@1 |
2026-08-14 |
| 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
- Handle errors in a Rust application with anyhow: attach context, keep the cause chain, log it without losing the cause, and recover the concrete error
- Packages
- Symbols
-
- anyhow::Context::context
- anyhow::Context::with_context
- anyhow::Error::chain
- anyhow::Error::root_cause
- anyhow::Error::downcast_ref
- anyhow::bail
- anyhow::ensure
- Environment
- rust 1
- Created
- 2026-08-14T08:53:52Z
Contract
- assert the bare io::Error for a missing path is NotFound and its Display carries os error 2
- assert Display of a context-wrapped error prints only the outermost context, not the io message
- assert alternate Display {:#} flattens the whole chain into one colon-joined line while {} does not
- assert chain() yields both context frames then the original io error, in that order
- assert root_cause() returns the original io error at the bottom of the chain
- assert Debug {:?} prints the multi-line report with a Caused by section
- assert anyhow::Error derefs to a dyn StdError that prints as the outermost frame, and that source() through that Deref yields the next frame
- assert downcast_ref recovers the io::Error and its NotFound kind through two layers of context
- assert downcast_ref recovers a concrete thiserror library type out of a context-wrapped anyhow error
- assert anyhow::Error is one pointer wide, smaller than the concrete thiserror error, which is as wide as its String field
- assert bail! and ensure! build a one-frame error from a plain message with no source
- assert an interpolated bail! message downcasts to String while an anyhow! bare literal downcasts to &str
- assert io::Error and ParseIntError both convert through ? with no From impl written
- assert context() on a None Option produces an error with no source
- assert with_context never runs its closure on the success path while context() builds its message even when the Result is Ok
Files
- Cargo.lock
- Cargo.toml
- csx.json
- src/main.rs