{
"id": "rust-linear-membership-in-loop",
"language": "rust",
"group": "performance",
"listingTitle": "Avoid repeated linear Rust membership checks",
"title": "Avoid repeated linear Rust membership checks",
"mvvm": false,
"defaultSeverity": "warn",
"legacyGroup": "performance",
"why": "Calling contains on a Vec scans linearly; doing that inside another loop can turn a linear pass into quadratic work.",
"suggestion": "Build a HashSet or BTreeSet before the loop when the collection is large enough and membership is the intended operation.",
"version": 1,
"semanticMaturity": "token",
"securityKind": "none",
"taxonomy": ["performance"],
"requirements": ["sourceText"],
"packs": ["rust"],
"implementation": "src/languages/rust/rules.rs",
"languages": ["rust"],
"frameworks": [],
"languageVersions": [],
"limitations": [
"Only function-local variables explicitly typed as Vec or initialized with Vec or vec! and then used with contains inside braced loops are reported.",
"Slices, fields, collection size, loop bounds, variable shadowing, and cases where a linear scan is intentionally cheaper than building an index are not inferred."
]
}