Sample
Prove how package:args caches and shares mutable default list instances across parses for unprovided multi-options
sha256:09efd7ba07568bb8934ab71bd5cda6503408067f4a024fd6365b7cf744124ce2
PUBLISHED
L3_CONTRACT_PASS
MIT-0
Execution evidence
Declared environment and signed verification runs are separated so you can see exactly what this sample proves.
Evidence basisSigned contract pass
Verification receipts1
Verification levelL3_CONTRACT_PASS
Declared environment
- Execution context
- dart
- Operating system
- linux
- Architecture
- x64
- Runtime
- dart
- Language
- dart
- Package manager
- pub
Verification-run environments
- Execution context
- dart 3
- Operating system
- linux debian · glibc
- Architecture
- x64
- Runtime
- dart 3
- Language
- dart
- Package manager
- pub
- Execution
- container · docker
CONTAINER_RUN · compile:SKIPPED · contract:PASS · load:PASS · resolve:PASS · pub@1 · 2026-08-17
Case
- Goal
- Prove how package:args caches and shares mutable default list instances across parses for unprovided multi-options HOW
- Packages
-
args 2.7.0
- Environment
- dart
- Created
- 2026-08-17T06:45:46Z
Commonly assumed
ArgResults returns an isolated or unmodifiable list for multi-option default values on each parse rather than sharing a mutable reference to the parser's internal default list.
The sample's author recorded this as what a developer or model would expect here. The contract below is what actually ran.
Contract
- ArgResults.multiOption returns the exact mutable defaultsTo list instance stored in Option without copying, causing identical() to return true across distinct parse calls and leaking in-place mutations into subsequent parses.
- assert mutating the list returned from an unparsed multiOption modifies the parser default for subsequent parse calls
- assert implicit default multi-options share the same empty mutable list across parse invocations
- assert explicitly provided CLI multi-options allocate a distinct unshared list that does not affect the default
- assert ArgResults.arguments and ArgResults.rest are unmodifiable collections that throw UnsupportedError on mutation
Files
- NOTES.md
- csx.json
- pubspec.lock
- pubspec.yaml
- test/contract.dart
Download the source artifact (tar.gz)
Origin Seeder
csx-seed
Verification receipts
- dart 3 · linux debian/x64 · docker · CONTAINER_RUN · compile:SKIPPED · contract:PASS · load:PASS · resolve:PASS · pub@1 · 2026-08-17 · ed25519:d91480838ac982c9