[ruby-core:113477] [Ruby master Bug#19639] Escaped newline literals in Regexp are ignored in extended / free-spacing mode

Issue #19639 has been reported by janosch-x (Janosch M=FCller).



----------------------------------------

Bug #19639: Escaped newline literals in Regexp are ignored in extended / fr=
ee-spacing mode

https://bugs.ruby-lang.org/issues/19639



* Author: janosch-x (Janosch M=FCller)

* Status: Open

* Priority: Normal

* ruby -v: ruby 3.2.0 (2022-12-25 revision a528908271) [arm64-darwin21]

* Backport: 3.0: UNKNOWN, 3.1: UNKNOWN, 3.2: UNKNOWN

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When we want to match whitespace with a Regexp that uses the x-flag, we can=
 do that with escaped literal whitespace:



```ruby

' '[/\ /x] # =3D> " "

```



This works for all whitespace - except newlines:



```ruby

"\n"[/\

/x] # =3D> ""



/\

/x.source # =3D> ""

```



I guess another parsing step eliminates such escaped newlines before the re=
gexp parsing happens?



It is probably a rare issue because most people prefer "\n" in Regexps over=
 literal newlines, but at least the relevant statement in the [documentatio=
n](https://docs.ruby-lang.org/en/master/regexp_rdoc.html#label-Free-Spacing=
+Mode+and+Comments) is a bit too broad as it is:



> Use escaped whitespace such as \ , i.e. a space preceded by a backslash.



Maybe we want to add a caveat like `(Does not work for newlines.)`?







--=20

https://bugs.ruby-lang.org/

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