Confusing error message: Operator '===' cannot be applied to types '1' and '0'. · Issue #25245 · microsoft/TypeScript (original) (raw)

TypeScript Version: 3.0.0-dev.20180623

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Code

function foo(x: [number]) { return x.length === 0; }

Bug:
The error message is: Operator '===' cannot be applied to types '1' and '0'.

I found this error very confusing. It took me a while to understand that the error meant that the type on the left hand side was 1.

In this case, I think we should instead report that the condition always evaluates to false.

Related Issues:

• true == false - cannot be applied to types 'false' and 'true'. #11178

/cc @chrisdias