[ASDAlexander77]

switch (5) { case "a": ... } compiled with no diagnostic: the switch's value was cast to the case's type (the number became a string) and compared.

Fix: a case whose type is a number, string, boolean or bigint (after literal and enum types) is an error when the switch's is another of those. It is reported at the case expression, with TypeScript's message. Unions, any, mixed enums and other types are left alone.

Repro (diagnostic-location/switch_case_type.ts):

function main() {
    const n = 5;
    switch (n) {
        case 5: print("five"); break;
        case "a": print("a"); break;   // 8:14: error: Type '"a"' is not comparable to type '5'
    }
}

ctest -C Release -j 8 --timeout 300: 100% passed, 0 failed (4092 tests on this branch).

🤖 Generated with Claude Code