[jira] [Closed] (LANG-1834) raction.getReducedFraction incorrectly throws for reducible Integer.MIN_VALUE numerator

["尹茂椿萱 (Jira)" <ji...@apache.org>]

     [ https://issues.apache.org/jira/browse/LANG-1834?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]

尹茂椿萱 closed LANG-1834.
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> raction.getReducedFraction incorrectly throws for reducible Integer.MIN_VALUE numerator
> ---------------------------------------------------------------------------------------
>
>                 Key: LANG-1834
>                 URL: https://issues.apache.org/jira/browse/LANG-1834
>             Project: Commons Lang
>          Issue Type: Bug
>          Components: lang.*, lang.math.*
>    Affects Versions: 3.20.0
>         Environment: * Java: 17
>  * Apache Commons Lang
>  * Test framework: JUnit 5
>            Reporter: 尹茂椿萱
>            Priority: Major
>             Fix For: 3.21.0
>
>
> {{Fraction.getReducedFraction(Integer.MIN_VALUE, -2)}} throws an {{{}ArithmeticException{}}}:
>  
> {{ArithmeticException: overflow: can't negate}}
> However, the fraction can be safely reduced to {{{}1073741824/1{}}}, since both values are representable as {{{}int{}}}.
> The implementation already contains a historical special case for {{Integer.MIN_VALUE}} as the denominator:
>  
> {{if (denominator == Integer.MIN_VALUE && (numerator & 1) == 0) \{
>     numerator /= 2;
>     denominator /= 2;
> }}}
> This modification handles some {{Integer.MIN_VALUE}} cases, but the handling is incomplete. It does not cover the case where {{Integer.MIN_VALUE}} is the numerator and the fraction can be reduced before sign normalization.
> For example:
>  
> {{Fraction.getReducedFraction(Integer.MIN_VALUE, -2);}}
> should return a fraction with numerator {{1073741824}} and denominator {{{}1{}}}, but currently throws an exception.
> *Suggested fix:* reduce the fraction before negating {{{}Integer.MIN_VALUE{}}}, or otherwise handle reducible {{Integer.MIN_VALUE}} numerators before sign normalization.



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