Bug #20246: Unexpected behavior for Regexp in Subexpression Calls on Ruby 3.3.0

• Status: Closed
• Assignee: -
• Target version: -
• ruby -v: ruby 3.3.0 (2023-12-25 revision 5124f9ac75) [arm64-darwin22]
• Backport: 3.0: UNKNOWN, 3.1: UNKNOWN, 3.2: UNKNOWN, 3.3: DONE

[bestwebua (Vladislav Trotsenko)]

Hello! A few days ago, after migration on 3.3.0 I have faced with issue inside subexpression calls.

An expected result on Ruby up to 3.3.0:

'1.2.3'[/(\d+)(\.\g<1>){2}/] # => "1.2.3"

An actual result on Ruby 3.3.0:

'1.2.3'[/(\d+)(\.\g<1>){2}/] # => nil

[make_now_just (Hiroya Fujinami)]

This is a bug in regex optimization.

Some optimizations have been disabled for memoization since 3.3.0. Therefore, another optimization was enabled, and that bug has surfaced.

By complicating the content of the first loop, we can confirm that the same problem occurs in 3.2 and earlier.

$ ruby --version
ruby 3.2.1 (2023-02-08 revision 31819e82c8) [arm64-darwin22]
$ ruby -e 'p "1.2.3"[/((?:\d|foo|bar)+)(\.\g<1>){2}/]'
nil

#9897 will fix this bug.

[naruse (Yui NARUSE)]

• Backport changed from 3.0: UNKNOWN, 3.1: UNKNOWN, 3.2: UNKNOWN, 3.3: UNKNOWN to 3.0: UNKNOWN, 3.1: UNKNOWN, 3.2: UNKNOWN, 3.3: REQUIRED

[make_now_just (Hiroya Fujinami)]

• Status changed from Open to Closed

Applied in changeset git|4a6384ed9358e8fb8464f6e37efb5477182f01db.

---

Fix [Bug #20246]: Don't set next_head_exact if a capture is called (#9897)

[naruse (Yui NARUSE)]

• Backport changed from 3.0: UNKNOWN, 3.1: UNKNOWN, 3.2: UNKNOWN, 3.3: REQUIRED to 3.0: UNKNOWN, 3.1: UNKNOWN, 3.2: UNKNOWN, 3.3: DONE

ruby_3_3 05787897f69087abdabee926971cdf364bd73730 merged revision(s) 18ee7c9a108bf3424814565377c8796e5e455cf7,4a6384ed9358e8fb8464f6e37efb5477182f01db.