tests/cases/compiler/constructorOverloads8.ts(2,5): error TS2392: Multiple constructor implementations are not allowed. tests/cases/compiler/constructorOverloads8.ts(3,5): error TS2392: Multiple constructor implementations are not allowed. ==== tests/cases/compiler/constructorOverloads8.ts (2 errors) ==== class C { constructor(x) { } ~~~~~~~~~~~~~~~~~~ !!! error TS2392: Multiple constructor implementations are not allowed. constructor(y, x) { } // illegal, 2 constructor implementations ~~~~~~~~~~~~~~~~~~~~~ !!! error TS2392: Multiple constructor implementations are not allowed. } class D { constructor(x: number); constructor(y: string); // legal, overload signatures for 1 implementation constructor(x) { } } interface I { new (x); new (x, y); // legal, overload signatures for (presumably) 1 implementation }