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No error when using uninitialized value in noImplicitAny & strictNullChecks mode #12002
Description
From master as of right now (7b34b612beda66b0812462a3feeabc63852cd842)
var x;
var y = 100 + x;Compile with strictNullChecks and noImplicitAny
Expected: Some sort of error for using x.
Actual: No error at all?
Activity
ahejlsberg commentedon Nov 2, 2016
This is actually by design. Your
var xis an implicit any variable that is tracked by control flow analysis (#11263). Because it hasn't been initialized, its control flow type in the100 + xexpression isundefined, and the+operator permitsundefinedas an operand value. If anything, we should discuss whether the numeric operators should be stricter with respect toundefinedandnull, but that's a different discussion.DanielRosenwasser commentedon Nov 2, 2016
Sure, that issue definitely sounds like something we should look into; is the type of
xstill going to beundefinedundernoImplicitAny?