Sample
clap 4.6.6: Assert clap 4 builder API traps: downcast panics on get_flag/get_one type mismatches, get_many vs Vec downcast for Append, num_args(0..=1) requirement for default_missing_value, and argv[0] program name consumption in try_get_matches_from
Verified sample for cargo clap 4.6.6: Assert clap 4 builder API traps: downcast panics on get_flag/get_one type mismatches, get_many vs Vec downcast for…
sha256:a58f6f21c612813f9bfb5172344901a8e9bacf1f11dea240f82a210daf63bc14
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
- Assert clap 4 builder API traps: downcast panics on get_flag/get_one type mismatches, get_many vs Vec downcast for Append, num_args(0..=1) requirement for default_missing_value, and argv[0] program name consumption in try_get_matches_from
- Packages
- Symbols
-
- clap::Command::try_get_matches_from
- clap::Arg::default_missing_value
- clap::Arg::num_args
- clap::ArgAction::Append
- clap::ArgAction::Count
- clap::ArgMatches::get_flag
- clap::ArgMatches::get_many
- clap::ArgMatches::get_one
- clap::ArgMatches::remove_one
- Environment
- rust
- Created
- 2026-08-16T08:02:26Z
Contract
- assert get_flag returns primitive bool while get_one::<bool> returns Option<&bool> with Some(&false) when an ArgAction::SetTrue flag is omitted
- assert calling get_flag on a string option or Count arg panics with a downcast error rather than returning false
- assert get_one::<u32> on a value_parser!(u16) argument panics with downcast mismatch instead of coercing
- assert get_one::<Vec<String>> on ArgAction::Append panics with downcast error and that get_many::<String> must be used to iterate values
- assert default_missing_value without num_args(0..=1) fails with ErrorKind::InvalidValue on bare flags, and that num_args(0..=1) is required for optional-value flags
- assert try_get_matches_from consumes the 0-th element as argv[0] binary name, failing required positional arguments if the binary name is omitted
- assert remove_one takes ownership returning Option<T> and causes subsequent get_one calls to return None
Files
- Cargo.lock
- Cargo.toml
- NOTES.md
- csx.json
- src/lib.rs
- tests/contract.rs