BUG: fix TypeError for invalid integer dates %Y%m%d with errors='ignore' (# GH 26583)

array_strptime returned TypeError when trying to slice 'too long' integer for the given format %Y%m%d (for example 2121010101).
After parsing date in the first 8 symbols it tried to return the remaining symbols in ValueError message as a slice of integer which in turn caused TypeError.
Converted to string value is now used to make slice for that ValueError message.
In case of 20209911, it tried to parse 20209911 to datetime(2020, 9, 9) and had 11 unparsed.

Author: nathalier

pandas/_libs/tslibs/strptime.pyx

@@ -140,13 +140,13 @@ def array_strptime(object[:] values, object fmt,
                     iresult[i] = NPY_NAT
                     continue
                 raise ValueError("time data %r does not match "
-                                 "format %r (match)" % (values[i], fmt))
+                                 "format %r (match)" % (val, fmt))
             if len(val) != found.end():
                 if is_coerce:
                     iresult[i] = NPY_NAT
                     continue
                 raise ValueError("unconverted data remains: %s" %
-                                 values[i][found.end():])
+                                 val[found.end():])
 
         # search
         else:
@@ -156,7 +156,7 @@ def array_strptime(object[:] values, object fmt,
                     iresult[i] = NPY_NAT
                     continue
                 raise ValueError("time data %r does not match format "
-                                 "%r (search)" % (values[i], fmt))
+                                 "%r (search)" % (val, fmt))
 
         iso_year = -1
         year = 1900

pandas/tests/indexes/datetimes/test_tools.py

@@ -114,6 +114,17 @@ def test_to_datetime_format_integer(self, cache):
         result = to_datetime(s, format='%Y%m', cache=cache)
         assert_series_equal(result, expected)
 
+    @pytest.mark.parametrize('int_date, expected', [
+        [20121030, datetime(2012, 10, 30)],
+        [20129930, 20129930],
+        [20120011, 20120011],
+        [2012010101, 2012010101]])
+    def test_int_to_datetime_format_YYYYMMDD_typeerror(self, int_date,
+                                                       expected):
+        # GH 26583
+        result = to_datetime(int_date, format='%Y%m%d', errors='ignore')
+        assert result == expected
+
     @pytest.mark.parametrize('cache', [True, False])
     def test_to_datetime_format_microsecond(self, cache):