[Bug #19004] `Complex.polar` handles complex singular `abs` argument

`Complex.polar` accepts Complex values as arguments for the polar form as long
as the value of the complex has no imaginary part (ie it is 'real'). In
`f_complex_polar` this is handled by extracting the real part of the arguments.
However in the case `polar` is called with only a single argument, the absolute
value (abs), then the Complex is created without applying a check on the type
of abs, meaning it is possible to create a Complex where the real part is itself
an instance of a Complex. This change removes the short circuit for the single
argument case meaning the real part extraction is performed correctly
(by f_complex_polar).

Also adds an example to `spec/ruby/core/complex/polar_spec.rb` to check that
the real part of a complex argument is correctly extracted and used in the
resulting Complex real and imaginary parts.

1 files changed, 16 insertions, 0 deletions

diff --git a/spec/ruby/core/complex/polar_spec.rb b/spec/ruby/core/complex/polar_spec.rb
index 2a5d8ebd69..3bb3751bc6 100644
--- a/spec/ruby/core/complex/polar_spec.rb
+++ b/spec/ruby/core/complex/polar_spec.rb
@@ -10,6 +10,22 @@ describe "Complex.polar" do
     ->{ Complex.polar(nil)      }.should raise_error(TypeError)
     ->{ Complex.polar(nil, nil) }.should raise_error(TypeError)
   end
+
+  ruby_bug "#19004", ""..."3.2" do
+    it "computes the real values of the real & imaginary parts from the polar form" do
+      a = Complex.polar(1.0+0.0i, Math::PI/2+0.0i)
+      a.real.should be_close(0.0, TOLERANCE)
+      a.imag.should be_close(1.0, TOLERANCE)
+      a.real.real?.should be_true
+      a.imag.real?.should be_true
+
+      b = Complex.polar(1+0.0i)
+      b.real.should be_close(1.0, TOLERANCE)
+      b.imag.should be_close(0.0, TOLERANCE)
+      b.real.real?.should be_true
+      b.imag.real?.should be_true
+    end
+  end
 end
 
 describe "Complex#polar" do