Fixes [Bug #19004]: Complex.polar handles complex singular abs argument
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Fixes [Bug #19004] [ruby-core:109879] `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.
nobu
reviewed
Oct 17, 2022
Co-authored-by: Nobuyoshi Nakada <[email protected]>
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Fixes [Bug #19004] [ruby-core:109879]
Link to issue https://bugs.ruby-lang.org/issues/19004
The issue
Complex.polaraccepts Complex values as arguments for the polar form (abs, arg), as long as the value of the complex has no imaginary part (ie it is 'real' in a mathematical sense, and according tonucomp_real_p, but not necessarily real in the Ruby Numeric sense of#real?). Eg:In
f_complex_polarthis is handled by extracting the real part of the arguments.However, in the case
Complex.polaris called with only a single argument (ie the absolute value is given only):The Complex is created directly without applying a check or attempting to extract the real part of abs. Thus it is possible to create a Complex where the real part is itself an instance of a Complex.
Reproduction
compare it to:
Proposed fix
The proposed change removes the short circuit for the single argument case, meaning the real part extraction is performed by
f_complex_polaras in the 2 argument case. The fact the polar argument is zero is then handled early on here inf_complex_polaranyway.Also the switch/case is removed as it seems in other situations of a 2 argument method with optional second argument, mostly a conditional is simply used.
The spec example
Added a spec to
spec/ruby/core/complex/polar_spec.rbwhich exposes the issue and validates the fix.The spec aims to more generically test the specified behaviour of Complex rather than checking its internal form, hence the test creates a Complex with
Complex.polarusing complex arguments & then validates that the computed parts of the resulting complex number are#real?As my first contribution please let me know if something needs changes or improvement.
Thanks for Ruby & everything you have all put into it ❤️