尹茂椿萱 created LANG-1834:
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Summary: 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
{{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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