tests/cases/compiler/controlFlowLoopAnalysis.ts(12,25): error TS2345: Argument of type 'number | undefined' is not assignable to parameter of type 'number'.
  Type 'undefined' is not assignable to type 'number'.


==== tests/cases/compiler/controlFlowLoopAnalysis.ts (1 errors) ====
    // Repro from #8418
    
    let cond: boolean;
    
    function foo(x: number): number { return 1; }
    
    function test1() {
        let x: number | undefined;
        while (cond) {
            while (cond) {
                while (cond) {
                    x = foo(x);
                            ~
!!! error TS2345: Argument of type 'number | undefined' is not assignable to parameter of type 'number'.
!!! error TS2345:   Type 'undefined' is not assignable to type 'number'.
                }
            }
            x = 1;
        }
    }
    
    // Repro from #8418
    
    function test2() {
        let x: number | undefined;
        x = 1;
        while (cond) {
            while (cond) {
                x = foo(x);
            }
        }
    }
    
    // Repro from #8511
    
    function mapUntilCant<a, b>(
        values: a[],
        canTake: (value: a, index: number) => boolean,
        mapping: (value: a, index: number) => b
    ): b[] {
        let result: b[] = [];
        for (let index = 0, length = values.length; index < length; index++) {
            let value = values[index];
            if (canTake(value, index)) {
                result.push(mapping(value, index));
            } else {
                return result;
            }
        }
        return result;
    }
    