test floating point casting better #1265
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tests/run-pass/floats.rs
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| assert_eq!((u32::MAX-127) as f32 as u32, u32::MAX); // rounding loss | ||
| assert_eq!((u32::MAX-128) as f32 as u32, u32::MAX-255); // rounding loss |
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@hanna-kruppe do these two (and the two "rounding loss" tests below) look like correct behavior to you? I experimentally determined these to be the closest to u32::MAX where the output of the roundtrip cast changes.
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@jodysankey you also seem to know floating point encoding stuff quite well, would be nice if you could have a look.
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Yes, they look exactly right to me. These are transition points from "odd significant + slightly less than 0.5 ULP" (which gets rounded down to uint::MAX - 1 ULP) to "odd significant + 0.5 ULP" (which is rounded up, so saturation kicks in when casting back to integer).
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@hanna-kruppe I only understood half of that, but that half sounds good. ;) Thanks!
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@bors r+ |
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📌 Commit b8a817f has been approved by |
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☀️ Test successful - checks-travis, status-appveyor |
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