Compatibility

RuboCop targets Ruby 2.0+ code analysis.[1]

RuboCop officially supports MRI (a.k.a. CRuby) and JRuby at runtime.

  • MRI 2.7+

  • JRuby 9.4+

The oldest supported JRuby version is derived from the oldest compatible MRI version.

RuboCop might be working with other Ruby implementations as well, but it’s tested only on MRI and JRuby.

Support Matrix

RuboCop generally aims to follow MRI’s own support policy - meaning RuboCop would support all officially supported MRI releases.[2] To give people extra time for a smooth transition, we’ve customarily provided support for about one year after EOL of a MRI version.[3]

The following table is the runtime support matrix.

Supported runtime Ruby version Last supported RuboCop version

1.9

0.41

2.0

0.50

2.1

0.57

2.2

0.68

2.3

0.81

2.4

1.12

2.5

1.28

2.6

1.50

2.7

-

3.0

-

3.1

-

3.2

-

3.3

-

3.4

-

4.0

-

4.1 (experimental)

-
The table above is about runtime support (which Ruby can run RuboCop itself). Code analysis support is broader — RuboCop can analyze code targeting Ruby 2.0+ regardless of the Ruby version it runs on. See TargetRubyVersion for details.

Parser engines

RuboCop supports two parser backends, configured via ParserEngine:

  • parser_whitequark — the Parser gem. Supports analyzing code targeting Ruby 2.0+.

  • parser_prism — the Prism translation layer. Supports analyzing Ruby 3.3+ code and tends to be faster.

Since RuboCop 1.75, parser_prism is used by default when TargetRubyVersion is 3.4 or higher.

Forward compatibility

RuboCop may ship support for features from in-development Ruby versions before they are officially released. Such support is considered experimental and may change to track upstream changes in the Ruby implementation.

1. As defined by its reference implementation MRI.
2. Typically the last 3 releases.
3. At the core team’s discretion this policy might be waived aside for MRI releases causing significant maintenance overhead.