tests/cases/compiler/functionCall9.ts(4,11): error TS2345: Argument of type 'string' is not assignable to parameter of type 'number'. tests/cases/compiler/functionCall9.ts(5,1): error TS2346: Supplied parameters do not match any signature of call target. ==== tests/cases/compiler/functionCall9.ts (2 errors) ==== function foo(a?:string, b?:number){}; foo('foo', 1); foo('foo'); foo('foo','bar'); ~~~~~ !!! error TS2345: Argument of type 'string' is not assignable to parameter of type 'number'. foo('foo', 1, 'bar'); ~~~~~~~~~~~~~~~~~~~~ !!! error TS2346: Supplied parameters do not match any signature of call target. foo();