Bug #20039
Updated by dbrown9@gmail.com (Dustin Brown) 8 months ago
Matching a US-ASCII string to a UTF-8 encoded regexp with multibyte characters works as expected.
```ruby
re = Regexp.new("\u2018".encode("UTF-8"))
"".encode("US-ASCII").match?(re)
=> false
```
However, if that regexp is used to initialize a new regexp, the comparison fails with a Invalid mutibyte character error.
```ruby
re = Regexp.new("\u2018".encode("UTF-8"))
"".encode("US-ASCII").match?(Regexp.new(re))
=> ArgumentError: regexp preprocess failed: invalid multibyte character
```
After a bunch of digging, I discovered that this error was due to the fixed encoding flag not being copied over from the original regexp. This [pull request](https://github.com/ruby/ruby/pull/9120) address the issue by copying the fixed encoding and no encoding flags during `reg_copy`.
Ref: https://github.com/ruby/ruby/pull/9120