Issue #20406 has been reported by andrykonchin (Andrew Konchin). ---------------------------------------- Misc #20406: Question about Regexp encoding negotiation https://bugs.ruby-lang.org/issues/20406 * 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. 1. 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. 2. In case of interpolated Regexp with encoding modifier I suppose there is no any encoding negotiation as far as if a Regexp fragment's encoding doesn't match a fixed encoding a SyntaxError is raised. Is this assumption correct? ```ruby /#{ "фв" } a/e # regexp encoding option 'e' differs from source encoding 'UTF-8' (SyntaxError) ``` -- https://bugs.ruby-lang.org/