[ruby-core:117428] [Ruby master Misc#20406] Question about Regexp encoding negotiation
From:
"Eregon (Benoit Daloze) via ruby-core" <ruby-core@...>
Date:
2024-04-03 10:33:40 UTC
List:
ruby-core #117428
Issue #20406 has been updated by Eregon (Benoit Daloze).
> It seems to behave a bit like string interpolation here
Specifically:
```
$ ruby -e '# encoding: EUC-JP
p ("a" + "\xC3\xA9".force_encoding("UTF-8") + "c").encoding'
#<Encoding:UTF-8>
```
But it seems very much unexpected for a `/e` regexp to have a UTF-8 encoding.
----------------------------------------
Misc #20406: Question about Regexp encoding negotiation
https://bugs.ruby-lang.org/issues/20406#change-107803
* Author: andrykonchin (Andrew Konchin)
* Status: Open
----------------------------------------
I am wondering what are the rules to calculate Regexp literal encoding in case an encoding modifier is specified.
>From the documentstion:
> By default, a regexp with only US-ASCII characters has US-ASCII encoding:
> ...
> A regular expression containing non-US-ASCII characters is assumed to use the source encoding. This can be overridden with one of the following modifiers.
> //n ...
> //u ...
> //e ...
> //s ...
Looking at the following examples I would assume that these rules are followed except one case:
```ruby
p /\xc2\xa1/e .encoding # EUC-JP
p /#{ }\xc2\xa1/e .encoding # EUC-JP
p /a/e .encoding # EUC-JP
p /a #{} a/e .encoding # EUC-JP
p /#{} a/e .encoding # US-ASCII
```
The last Regexp `/#{} a/e` is supposed to have `EUC-JP` encoding but has `US-ASCII`. So I am wondering what rule is applied in this case.
--
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