Note: this also happens with gsv4, but, here, I am only concerned with gsv3 which is no longer maintained, and will then probably not be fixed upstream.

Description of problem:
I am the packager of notekit which depends on gtksourceviewmm3, and thus gtksourceview3. A port to gsv4 is impossible due to the unavailability of the mm bindings for gsv4.

We noticed that the recent glib2 move to pcre2 broke notekit entirely on f37/rawhide (it relies on gsv3 to do Markdown formatting and syntax highlighting), and disabling syntax highlighting solves Markdown formatting (as it is not broken by the pcre2 change), but leaves us without syntax highlighting, a relatively important part of the software.

The regex issues will probably be fixed in gsv4, so I'm asking if it would be possible to backport these to gsv3?

The files which seems to need patching are asp.lang, html.lang and css.lang.

Version-Release number of selected component (if applicable):
~ 
❯ rpm -q gtksourceview3
gtksourceview3-3.24.11-8.fc37.x86_64

~ 
❯ rpm -q gtksourceviewmm3
gtksourceviewmm3-3.18.0-15.fc37.x86_64

How reproducible:
Always

Steps to Reproduce:
1. Open NoteKit
2. No Markdown formatting
3. Disable syntax highlighting and restarting NoteKit
4. Markdown formatting is back, but no syntax highlighting

Actual results:
```
(notekit:307145): GtkSourceView-WARNING **: 14:09:18.135: Failed to load '/usr/share/notekit/sourceview/markdown.lang': In file '/tmp/notekit.gsv/markdownlisting.lang' referenced from '/usr/share/notekit/sourceview/markdown.lang': In file '/usr/share/gtksourceview-3.0/language-specs/asp.lang' referenced from '/usr/share/notekit/sourceview/markdown.lang': In file '/usr/share/gtksourceview-3.0/language-specs/html.lang' referenced from '/usr/share/notekit/sourceview/markdown.lang': In file '/usr/share/gtksourceview-3.0/language-specs/css.lang' referenced from '/usr/share/notekit/sourceview/markdown.lang': Error while compiling regular expression (?i-x)(?:(?ix)
      (?:
        (?:
          -- |
          -? (?:(?ix)
      (?:
        [a-z_] |
        (?:(?i-x)[\x{80}-\x{10ffff}]) |
        (?:(?ix)
      (?:
        \\                   # backslash
        (?:
          [^\n\r\f0-9a-f] |  # not newline or hex digit; or
          [0-9a-f]{1,6} \s?  # 1-6 hex digits, trailing whitespace (not necessary in some cases)
        )
      )
    
)
      )
    
)
        )
        (?:(?ix)
      (?>
        (?:
          [a-z0-9_-]+ |
          (?:(?i-x)[\x{80}-\x{10ffff}])+ |
          (?:(?ix)
      (?:
        \\                   # backslash
        (?:
          [^\n\r\f0-9a-f] |  # not newline or hex digit; or
          [0-9a-f]{1,6} \s?  # 1-6 hex digits, trailing whitespace (not necessary in some cases)
        )
      )
    
)+
        )+
      )
    
)?
      )
    
) at char 127: plage déclassée dans la classe de caractère
```

Expected results:
It works.

Additional info:
The same issues are encountered in gsv4.