Bug #20421: String#index and String#byteindex don't clear `$~` when offset > size (or bytesize)

• Status: Closed
• Assignee: -
• Target version: -
• ruby -v: 3.2.2
• Backport: 3.1: REQUIRED, 3.2: REQUIRED, 3.3: DONTNEED

[andrykonchin (Andrew Konchin)]

When String#index and String#byteindex are called with Regexp and offset they clear $~ (that contains result of the last Regexp matching) when offset < -size. But they don't clear $~ when offset > size what seems inconsistent:

"a".index(/a/)
p $~ # => #<MatchData "a">

string = "blablabla"
string.index(/bla/, string.length + 1)
p $~ # => #<MatchData "a">

[andrykonchin (Andrew Konchin)]

• Description updated (diff)

[jeremyevans0 (Jeremy Evans)]

• Status changed from Open to Closed
• 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: DONTNEED

The issue doesn't affect 3.3 and master. It appears fixed by 9dcdffb8bf8a3654fd78bf1a58b30c8e13888a7a. If you would like the fix backported to 3.2, please respond.

[Eregon (Benoit Daloze)]

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

Given this is a clear bug (which can break programs' logic) I think it's good to backport.

[Eregon (Benoit Daloze)]

We should also add a test so this doesn't regress on 3.3 & master, that seems fine as a ruby_bug spec in ruby/spec.

[hsbt (Hiroshi SHIBATA)]

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

[byroot (Jean Boussier)]

I got a ruby-bug spec at https://github.com/ruby/ruby/pull/10750

As for 9dcdffb8bf8a3654fd78bf1a58b30c8e13888a7a, it might make sense to make a more targeted fix for backport, as this is a more general refactor.

[byroot (Jean Boussier)]

Here's more targeted patch for Ruby 3.2: https://github.com/ruby/ruby/pull/10751