Issue #20406 has been updated by Eregon (Benoit Daloze).
By default, a regexp with only US-ASCII characters has US-ASCII encoding:
I was wondering what kind of check is used for that and it seems to be checking the Regexp source when building it (makes sense): ``` $ ruby -e 'p /a/.encoding' #<Encoding:US-ASCII> $ ruby -e 'p /a#{}b/.encoding' #<Encoding:US-ASCII> $ ruby -e 'p /a#{"c"}b/.encoding' #<Encoding:US-ASCII> $ ruby -e 'p /a#{"é"}b/.encoding' #<Encoding:UTF-8> ``` ---------------------------------------- Misc #20406: Question about Regexp encoding negotiation https://bugs.ruby-lang.org/issues/20406#change-107801 * 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. -- https://bugs.ruby-lang.org/