65c2b2b509
Found by running this command:
$ git ls-files -z|xargs -0 perl -0777 -n \
-e 'while (/\b(then?|[iao]n|i[fst]|but|f?or|at|and|[dt]o)\s+\1\b/gims)' \
-e ' {' \
-e ' $n = ($` =~ tr/\n/\n/ + 1);' \
-e ' ($v = $&) =~ s/\n/\\n/g;' \
-e ' print "$ARGV:$n:$v\n";' \
-e ' }'
Why not just git grep -E ...?
That wouldn't work then the doubled words are separated by a newline.
This is derived from a Makefile syntax-check rule in gnulib's maint.mk:
http://git.sv.gnu.org/cgit/gnulib.git/tree/top/maint.mk
Signed-off-by: Jim Meyering <meyering@redhat.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>