patch 8.0.0645: no error for illegal back reference in NFA engine
Problem: The new regexp engine does not give an error for using a back
reference where it is not allowed. (Dominique Pelle)
Solution: Check the back reference like the old engine. (closes #1774)
diff --git a/src/testdir/test_regexp_latin.vim b/src/testdir/test_regexp_latin.vim
index 247e5e6..a8fa64d 100644
--- a/src/testdir/test_regexp_latin.vim
+++ b/src/testdir/test_regexp_latin.vim
@@ -62,3 +62,13 @@
call assert_equal(expected, actual)
endfor
endfunc
+
+func Test_backref()
+ new
+ call setline(1, ['one', 'two', 'three', 'four', 'five'])
+ call assert_equal(3, search('\%#=1\(e\)\1'))
+ call assert_equal(3, search('\%#=2\(e\)\1'))
+ call assert_fails('call search("\\%#=1\\(e\\1\\)")', 'E65:')
+ call assert_fails('call search("\\%#=2\\(e\\1\\)")', 'E65:')
+ bwipe!
+endfunc