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Convert equality check with 'NaN' to 'isNaN' call

Reports an equality check with Float.NaN or Double.NaN that should be replaced with an isNaN() check.

According to IEEE 754, equality check against NaN always returns false, even for NaN == NaN. Therefore, such a check is likely to be a mistake.

The quick-fix replaces comparison with isNaN() check that uses a different comparison technique and handles NaN values correctly.

Example:

fun check(value: Double): Boolean { return Double.NaN == value }

After the fix is applied:

fun check(value: Double): Boolean { return value.isNaN() }

Inspection Details

By default bundled with:

IntelliJ IDEA 2024.1, Qodana for JVM 2024.1,

Can be installed with plugin:

Kotlin, 241.16690-IJ

Last modified: 29 April 2024