String collisions are not detected when the strings come from enums

TypeScript Version: 3.1.0-dev.20180822

Search Terms: enum string

Code

enum BuildingActions {
    sort = "sort"
}

enum AlarmActions {
    sort = "sort"
}

interface SortBuildingsAction {
    type: BuildingActions.sort,
    buildingCriteria: any
}

interface SortAlarmsAction {
    type: AlarmActions.sort,
    alarmCriteria: any
}

type Action = SortAlarmsAction | SortBuildingsAction;

function reduce(a: Action) {
    switch (a.type) {
        case BuildingActions.sort:
            console.log(a.buildingCriteria)
            break;
        case AlarmActions.sort:
            console.log(a.alarmCriteria);
            break
    }
}

Expected behavior:

• Type error on lines 22-30: BuildingActions.sort is equals to AlarmActions.sort.
• Dead code detected at lines 26-28.

Actual behavior: Code compiles to Javascript without any warnings. The case always enters on the first branch.

Playground Link: https://www.typescriptlang.org/play/#src=enum BuildingActions { sort %3D "sort" } enum AlarmActions { sort %3D "sort" } interface SortBuildingsAction { type%3A BuildingActions.sort%2C buildingCriteria%3A any } interface SortAlarmsAction { type%3A AlarmActions.sort%2C alarmCriteria%3A any } type Action %3D SortAlarmsAction | SortBuildingsAction%3B function reduce(a%3A Action) { switch (a.type) { case BuildingActions.sort%3A console.log(a.buildingCriteria) break%3B case AlarmActions.sort%3A console.log(a.alarmCriteria)%3B break } }

Related Issues: No related issues found.

[RyanCavanaugh]

@Kingwl This should just be a specific logic in detecting duplicate case labels. Not sure if that answers your question

[ajafff]

Until this is implemented/fixed in TypeScript, you can use a linter rule I wrote to detect duplicate case clauses in switch statements: no-duplicate-case For a description on how to use it, see https://github.com/fimbullinter/wotan/blob/master/packages/wotan/README.md