RULES "minusFloat x x" and "timesFloat 0.0 x" break IEEE-754 compatibility
In GHC/Base.lhs, a comment around line ~778 notes that the following rules for Doubles give the wrong answer for NaN:
"minusDouble x x" forall x#. (-##) x# x# = 0.0##
"timesDouble 0.0 x" forall x#. (*##) 0.0## x# = 0.0##
"timesDouble x 0.0" forall x#. (*##) x# 0.0## = 0.0##However, immediately above are corresponding rules for Floats:
"minusFloat x x" forall x#. minusFloat# x# x# = 0.0#
"timesFloat x 0.0" forall x#. timesFloat# x# 0.0# = 0.0#
"timesFloat0.0 x" forall x#. timesFloat# 0.0# x# = 0.0#These should probably be removed.
Trac metadata
| Trac field | Value |
|---|---|
| Version | 7.0.3 |
| Type | Bug |
| TypeOfFailure | OtherFailure |
| Priority | normal |
| Resolution | Unresolved |
| Component | libraries/base |
| Test case | |
| Differential revisions | |
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| Related | |
| Blocking | |
| CC | |
| Operating system | |
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