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Incorrect f32::NAN as u64/u128 conversion #75

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ghost opened this issue Sep 1, 2021 · 2 comments
Open

Incorrect f32::NAN as u64/u128 conversion #75

ghost opened this issue Sep 1, 2021 · 2 comments
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@ghost
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ghost commented Sep 1, 2021

The code generated for black_box(f32::NAN) as u64/u128 converts it to some junk, but correct result is 0. This happens only with f32::NAN and only when converted to u64/u128. Conversion into i64/i128 works fine, as well as conversions intou8, i8, ... u32,i32.
@antoyo antoyo added the bug Something isn't working label Oct 31, 2021
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antoyo commented Feb 1, 2022 •
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This is because gcc gives a negative NAN for 0.0 / 0.0.

Does Rust define that the sign of NAN should be positive?

Possibly relevant: rust-lang/rust#81261

@antoyo antoyo mentioned this issue Feb 19, 2022
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@RalfJung
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rust-lang/rust#55131 also seems very relevant.

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