[GROOVY-10800] The % operator returns unexpected results for negative numbers for BigIntegers

• Type: Bug
• Status: Closed
• Priority: Major
• Resolution: Fixed
• Fix Version/s: 5.0.0-alpha-1
• Labels: breaking
• Assignee: Paul King
• Reporter: Paul King
• Created: 28/Oct/22 08:21
• Updated: 23/Aug/23 09:11
• Resolved: 25/Mar/23 22:39

Description

As a follow-up to GROOVY-10786, the behavior of the % operator for BigInteger is a little strange for negative numbers.

def nums = [-10, -10L, -10f, -10d, -10G, -10.0G]
assert nums.collect{ it % 3 } == [-1, -1, -1f, -1d, 2G, -1.0G]

In our documentation, we call "%" the remainder operator as does Java, though also like Java, the operator is often informally referred to as the "mod" operator.

I suggest we change the BigInteger "%" operator to be the same as the other numeric types, i.e. use remainder not mod.
This has some ramifications which I'll bring up on the mailing list.

Issue Links

• relates to: GROOVY-10980 Provide an AST transform to rename operator methods
• relates to: GROOVY-10786 Cannot call modulo operator (%) on BigDecimal types