[thomasklemm]

Thank you for maintaining date.

Date#<=> raises ArgumentError ("comparison of Rational with NaN failed") when the other value is Float::NAN or BigDecimal("NaN"), and Date#== raises with it, while 1 <=> Float::NAN, Rational(1) <=> Float::NAN and Time.now <=> Float::NAN return nil. cmp_gen passes the result of ajd <=> other to rb_cmpint, which turns the nil from Rational#<=> into that exception.

This returns the result unchanged. Date <=> NaN is now nil and Date == NaN is false, while Date < NaN still raises ArgumentError, as for Integer. The new test covers both NaNs, so I added bigdecimal to the development group. The suite passes on Ruby 4.0.9 and master.

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_{Found while comparing Active Model's changed? on Rails 8.1 and main with random attribute values, where a NaN assigned to a date attribute raised (record, part of my research project Lowrail).}