[GROOVY-9710] List.intersect changes behavior from Groovy 2.4 and Groovy 2.5+

• Type: Bug
• Status: Closed
• Priority: Major
• Resolution: Not A Bug
• Affects Version/s: 3.0.5, 2.5.13
• Component/s: groovy-runtime
• Environment: Ubuntu 18.04.5 LTS ; OpenJDK Java 1.8.0_265 (Private Build 25.265-b01) ; Gradle 5.6.3
• Assignee: Unassigned
• Reporter: Sam Gleske
• Created: 01/Sep/20 05:24
• Updated: 02/Sep/20 21:09
• Resolved: 02/Sep/20 21:08

Description

Description

List.intersect preserves the ordering of the source list in Groovy 2.4 but instead takes the ordering of the intersecting list. This can lead to unexpected behavior in Groovy applications as code migrates to newer versions of Groovy.

Example code

// Passes assertion in Groovy 2.4.20 but fails in Groovy 2.5.13 and 3.0.5

assert ['a', 'b'].intersect(['c', 'b', 'a']) == ['a', 'b']

Expected behavior

The order of the first list is preserved.

Actual behavior

The order of the second list takes precedence.

Groovy version matrix

Groovy version	Behavior
2.4.20	Assertion passes
2.5.13	Assertion fails (order reversed)
3.0.5	Assertion fails (order reversed)