[Bug 296791] powl returns wrong sign

https://bugs.freebsd.org/bugzilla/show_bug.cgi?id=3D296791

            Bug ID: 296791
           Summary: powl returns wrong sign
           Product: Base System
           Version: 15.1-RELEASE
          Hardware: amd64
                OS: Any
            Status: New
          Severity: Affects Many People
          Priority: ---
         Component: standards
          Assignee: [email protected]
          Reporter: [email protected]
 Attachment #272844 text/plain
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Created attachment 272844
  --> https://bugs.freebsd.org/bugzilla/attachment.cgi?id=3D272844&action=
=3Dedit
reproducible example

C23 =C2=A77.12.1 p5:

> A floating result overflows if a finite result value with ordinary accura=
cy would have magnitude
> (absolute value) too large for the representation with full precision in =
the specified type. A result
> that is exactly an infinity does not overflow. If a floating result overf=
lows and default rounding
> is in effect, then the function returns the value of the macro HUGE_VAL, =
HUGE_VALF, or HUGE_VALL
> according to the return type, **with the same sign as the correct value o=
f the function.**

However, when an overflow or an underflow occurs in powl, it returns a wrong
sign in some patterns.

Wrong patterns:

powl(-3.0L, odd) =3D inf should be -inf
powl(-1.0L / 3.0L, odd) =3D 0 should be -0
powl(-3.0L, -odd) =3D 0 should be -0
powl(-1.0L / 3.0L, -odd) =3D inf should be -inf

Correct patterns:

powl(3.0L, even) =3D inf should be inf
powl(INFINITY, even) =3D inf should be inf
powl(3.0L, odd) =3D inf should be inf
powl(INFINITY, odd) =3D inf should be inf
powl(1.0L / 3.0L, even) =3D 0 should be 0
powl(1.0L / INFINITY, even) =3D 0 should be 0
powl(1.0L / 3.0L, odd) =3D 0 should be 0
powl(1.0L / INFINITY, odd) =3D 0 should be 0
powl(-3.0L, even) =3D inf should be inf
powl(-INFINITY, even) =3D inf should be inf
powl(-INFINITY, odd) =3D -inf should be -inf
powl(-1.0L / 3.0L, even) =3D 0 should be 0
powl(-1.0L / INFINITY, even) =3D 0 should be 0
powl(-1.0L / INFINITY, odd) =3D -0 should be -0
powl(3.0L, -even) =3D 0 should be 0
powl(INFINITY, -even) =3D 0 should be 0
powl(3.0L, -odd) =3D 0 should be 0
powl(INFINITY, -odd) =3D 0 should be 0
powl(1.0L / 3.0L, -even) =3D inf should be inf
powl(1.0L / INFINITY, -even) =3D inf should be inf
powl(1.0L / 3.0L, -odd) =3D inf should be inf
powl(1.0L / INFINITY, -odd) =3D inf should be inf
powl(-3.0L, -even) =3D 0 should be 0
powl(-INFINITY, -even) =3D 0 should be 0
powl(-INFINITY, -odd) =3D -0 should be -0
powl(-1.0L / 3.0L, -even) =3D inf should be inf
powl(-1.0L / INFINITY, -even) =3D inf should be inf
powl(-1.0L / INFINITY, -odd) =3D -inf should be -inf

You can easily reproduce the issue with the attached file.

> clang -lm test.c
> ./a.out

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