Bug #15491: r62701 introduced the incompatibility of Complex#+, #-, and #* removing #ifndef PRESERVE_SIGNEDZERO

• Status: Closed
• Assignee: mrkn (Kenta Murata)
• Target version: -
• ruby -v: ruby 2.6.0p0 (2018-12-25 revision 66547) [x86_64-linux]
• Backport: 2.4: DONTNEED, 2.5: DONTNEED, 2.6: DONE

[mrkn (Kenta Murata)]

In r62701, preprocessor conditions #ifndef PRESERVE_SIGNEDZERO in f_add, f_mul, and f_sub functions were removed.
These changes introduced the incompatibility for some special cases.

For example, the results of the following code shows the different sign of the imaginary part:

p Complex(-0.0, 0) * Complex(0, 0)
#=> (-0.0+0.0i)  on 2.5.3
#=> (-0.0-0.0i)  on 2.6.0

Moreover, the following code shows the different values in the real part:

class Integer
  def +(*); 42; end
end
p Complex(1, 2) + Complex(0, 1)
#=> (42+42i) on 2.5.3
#=> (0+42i)  on 2.6.0

[mrkn (Kenta Murata)]

I made a patch https://github.com/ruby/ruby/pull/2062

[mrkn (Kenta Murata)]

• Status changed from Assigned to Closed

Applied in changeset trunk|r66688.

---

complex.c: fix against redefining component methods

This fixes the incompatibility (maybe unintentionally) introduced by
removal of #ifndef PRESERVE_SIGNEDZERO guards in f_add, f_mul, and
f_sub functions in r62701. [Bug #15491] [ruby-core:90843]

[naruse (Yui NARUSE)]

• Backport changed from 2.4: UNKNOWN, 2.5: UNKNOWN, 2.6: UNKNOWN to 2.4: DONTNEED, 2.5: DONTNEED, 2.6: REQUIRED

[naruse (Yui NARUSE)]

• Backport changed from 2.4: DONTNEED, 2.5: DONTNEED, 2.6: REQUIRED to 2.4: DONTNEED, 2.5: DONTNEED, 2.6: DONE

ruby_2_6 r66854 merged revision(s) 66681,66682,66684,66688,66697,66751,66693,66694.