[ruby-core:118819] [Ruby master Bug#20662] pack("g") completely discards any actual NaN value and always packs the same single-precision bytes for a NaN
From:
"nobu (Nobuyoshi Nakada) via ruby-core" <ruby-core@...>
Date:
2024-08-09 13:13:26 UTC
List:
ruby-core #118819
Issue #20662 has been updated by nobu (Nobuyoshi Nakada).
https://github.com/ruby/ruby/pull/11352
I'm uncertain that it is a nice idea to expose such internals of `Float` though.
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Bug #20662: pack("g") completely discards any actual NaN value and always packs the same single-precision bytes for a NaN
https://bugs.ruby-lang.org/issues/20662#change-109383
* Author: cabo (Carsten Bormann)
* Status: Open
* ruby -v: ruby 3.3.4 (2024-07-09 revision be1089c8ec) [arm64-darwin23]
* Backport: 3.1: UNKNOWN, 3.2: UNKNOWN, 3.3: UNKNOWN
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`pack("G")`/`unpack("G")` works great with NaN values. However,
- `pack("g")` completely discards any actual NaN value and always packs the same bytes for a NaN
("bug as implemented" in `VALUE_to_float`)
Also:
- `unpack("g")` always sets the quiet bit to 1 in the `Float` result
(location of bug not obvious to me)
---Files--------------------------------
showbug.rb (3.21 KB)
showbug-arm.txt (5.48 KB)
showbug-intel.txt (5.48 KB)
--
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