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https://issues.apache.org/jira/browse/LANG-1834?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=18116674#comment-18116674
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Makarand Hinge commented on LANG-1834:
--------------------------------------
[~ggregory]
I was able to reproduce this issue with
{{{}Fraction.getReducedFraction(Integer.MIN_VALUE, -2){}}}, which currently
throws {{{}ArithmeticException: overflow: can't negate{}}}.
I plan to work on a fix for this. The approach will be to handle the reducible
{{Integer.MIN_VALUE}} numerator case before sign normalization, so that the
fraction can be reduced safely before attempting to negate the numerator. I’ll
also preserve the existing overflow checks for cases where
{{Integer.MIN_VALUE}} genuinely cannot be represented after negation.
I’ll add a regression test for this case and verify the existing test suite to
make sure the change does not affect other {{Fraction}} behavior.
> 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
>
> {{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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