Index: Lib/test/test_re.py
===================================================================
--- Lib/test/test_re.py	(revision 78129)
+++ Lib/test/test_re.py	(working copy)
@@ -714,6 +714,16 @@
         self.assertRaises(TypeError, re.finditer, "a", {})
         self.assertRaises(OverflowError, _sre.compile, "abc", 0, [long_overflow])
 
+    def test_bug_2537(self):
+        # issue 2537: empty submatches
+        for outer_op in ('{0,}', '*', '+', '{1,187}'):
+            for inner_op in ('{0,}', '*', '?'):
+                r = re.compile("^((x|y)%s)%s" % (inner_op, outer_op))
+                m = r.match("xyyzy")
+                self.assertEqual(m.group(0), "xyy")
+                self.assertEqual(m.group(1), "")
+                self.assertEqual(m.group(2), "y")
+
 def run_re_tests():
     from test.re_tests import tests, SUCCEED, FAIL, SYNTAX_ERROR
     if verbose:
Index: Lib/sre_compile.py
===================================================================
--- Lib/sre_compile.py	(revision 78129)
+++ Lib/sre_compile.py	(working copy)
@@ -354,8 +354,6 @@
 def _simple(av):
     # check if av is a "simple" operator
     lo, hi = av[2].getwidth()
-    if lo == 0 and hi == MAXREPEAT:
-        raise error, "nothing to repeat"
     return lo == hi == 1 and av[2][0][0] != SUBPATTERN
 
 def _compile_info(code, pattern, flags):