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tests/cases/conformance/expressions/typeGuards/typeGuardsDefeat.ts(21,20): error TS2362: The left-hand side of an arithmetic operation must be of type 'any', 'number', 'bigint' or an enum type.
tests/cases/conformance/expressions/typeGuards/typeGuardsDefeat.ts(21,24): error TS2363: The right-hand side of an arithmetic operation must be of type 'any', 'number', 'bigint' or an enum type.
tests/cases/conformance/expressions/typeGuards/typeGuardsDefeat.ts(32,23): error TS2362: The left-hand side of an arithmetic operation must be of type 'any', 'number', 'bigint' or an enum type.
tests/cases/conformance/expressions/typeGuards/typeGuardsDefeat.ts(32,27): error TS2363: The right-hand side of an arithmetic operation must be of type 'any', 'number', 'bigint' or an enum type.
==== tests/cases/conformance/expressions/typeGuards/typeGuardsDefeat.ts (4 errors) ====
// Also note that it is possible to defeat a type guard by calling a function that changes the
// type of the guarded variable.
function foo(x: number | string) {
function f() {
x = 10;
}
if (typeof x === "string") {
f();
return x.length; // string
}
else {
return x++; // number
}
}
function foo2(x: number | string) {
if (typeof x === "string") {
return x.length; // string
}
else {
var f = function () {
return x * x;
~
!!! error TS2362: The left-hand side of an arithmetic operation must be of type 'any', 'number', 'bigint' or an enum type.
~
!!! error TS2363: The right-hand side of an arithmetic operation must be of type 'any', 'number', 'bigint' or an enum type.
};
}
x = "hello";
f();
}
function foo3(x: number | string) {
if (typeof x === "string") {
return x.length; // string
}
else {
var f = () => x * x;
~
!!! error TS2362: The left-hand side of an arithmetic operation must be of type 'any', 'number', 'bigint' or an enum type.
~
!!! error TS2363: The right-hand side of an arithmetic operation must be of type 'any', 'number', 'bigint' or an enum type.
}
x = "hello";
f();
}
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