From: "vlazar (Vlad Zarakovsky)" <noreply@...>
Date: 2022-01-11T08:14:54+00:00
Subject: [ruby-core:107045] [Ruby master Bug#18471] Regex#match(re, position) with start of a string anchors ^ and \A

Issue #18471 has been reported by vlazar (Vlad Zarakovsky).

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Bug #18471: Regex#match(re, position) with start of a string anchors ^ and \A
https://bugs.ruby-lang.org/issues/18471

* Author: vlazar (Vlad Zarakovsky)
* Status: Open
* Priority: Normal
* Backport: 2.6: UNKNOWN, 2.7: UNKNOWN, 3.0: UNKNOWN, 3.1: UNKNOWN
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Found this. Is it a bug in `Regex#match(re, position)`?

From `Regex#match` docs

> If the second parameter is present, it specifies the position in the string to begin the search.

```rb
str = "hello world"
/^world/.match(str, 6) # => nil
/\Aworld/.match(str, 6) # => nil
```

I would expect ���specifies the position in the string to begin the search��� would mean staring from position 6 in ���hello world��� should be equivalent to staring with position 0 in a string ���world��� and thus ^ or \A should match in this case too.

Consider another example. If I use the same with `StringScanner#scan` it works as I would expect:

```rb
require "strscan"

str = "hello world"
scanner = StringScanner.new(str)
scanner.pos = 6
scanner.scan /^world/ # => "world"
scanner.pos = 6
scanner.scan /\Aworld/ # => "world"
```

To me these 2 cases (at least looking into current API docs) should work the same and having a difference in behavior looks like a bug to me.



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