tests/cases/compiler/genericConstraint1.ts(8,8): error TS2344: Type 'string' does not satisfy the constraint 'number'. ==== tests/cases/compiler/genericConstraint1.ts (1 errors) ==== class C { public bar2(x: T, y: U): T { return null; } } var x = new C(); x.bar2(2, ""); ~~~~~~ !!! error TS2344: Type 'string' does not satisfy the constraint 'number'.