Breaks for me on perl 5.26. 
perl -E 'local $_ = "foo"; say "Start" if /\G foo/gcx; say "Mid" if /\
+G .*/gcx; say "End" if /\G \z/gcx'
Start
Mid

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Should instead print 
Start
Mid
End

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Here is a more extended item looking at pos as well. 
perl -E 'local $_ = "foo"; say "Start" if /\G foo/gcx; say pos; say "M
+id" if /\G .*/gcx; say pos; say "End" if /\G \z/gcx; say "At End" if 
+pos == length'
Start
3
Mid
3
At End

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my @a=qw(random brilliant braindead); print $a[rand(@a)];

In reply to Re^2: Seeking clarification on possible bug in regex using \G and /gc by Rhandom
in thread Seeking clarification on possible bug in regex using \G and /gc by davido

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