tests/cases/compiler/implicitConstParameters.ts(38,27): error TS18048: 'x' is possibly 'undefined'.
tests/cases/compiler/implicitConstParameters.ts(44,27): error TS18048: 'x' is possibly 'undefined'.


==== tests/cases/compiler/implicitConstParameters.ts (2 errors) ====
    function doSomething(cb: () => void) {
        cb();
    }
    
    function fn(x: number | string) {
      if (typeof x === 'number') {
          doSomething(() => x.toFixed());
      }
    }
    
    function f1(x: string | undefined) {
        if (!x) {
            return;
        }
        doSomething(() => x.length);
    }
    
    function f2(x: string | undefined) {
        if (x) {
            doSomething(() => {
                doSomething(() => x.length);
            });
        }
    }
    
    function f3(x: string | undefined) {
        inner();
        function inner() {
            if (x) {
                doSomething(() => x.length);
            }
        }
    }
    
    function f4(x: string | undefined) {
        x = "abc";  // causes x to be considered non-const
        if (x) {
            doSomething(() => x.length);
                              ~
!!! error TS18048: 'x' is possibly 'undefined'.
        }
    }
    
    function f5(x: string | undefined) {
        if (x) {
            doSomething(() => x.length);
                              ~
!!! error TS18048: 'x' is possibly 'undefined'.
        }
        x = "abc";  // causes x to be considered non-const
    }
    
    
    function f6(x: string | undefined) {
        const y = x || "";
        if (x) {
            doSomething(() => y.length);
        }
    }