Remove warnings and fix functionality

Author: Aloqeely

pandas/_libs/tslibs/conversion.pyx

@@ -610,7 +610,7 @@ cdef _TSObject convert_str_to_tsobject(str ts, tzinfo tz,
             ts, &dts, &out_bestunit, &out_local,
             &out_tzoffset, False
         )
-        if not string_to_dts_failed:
+        if not string_to_dts_failed and not dayfirst:
             reso = get_supported_reso(out_bestunit)
             check_dts_bounds(&dts, reso)
             obj = _TSObject()

pandas/core/tools/datetimes.py

@@ -135,11 +135,10 @@ def _guess_datetime_format_for_array(arr, dayfirst: bool | None = False) -> str
                 return guessed_format
             # If there are multiple non-null elements, warn about
             # how parsing might not be consistent
-            if dayfirst or tslib.first_non_null(arr[first_non_null + 1 :]) != -1:
+            if tslib.first_non_null(arr[first_non_null + 1 :]) != -1:
                 warnings.warn(
                     "Could not infer format, so each element will be parsed "
-                    "individually, falling back to `dateutil` which does not take the "
-                    "dayfirst parameter in consideration. To ensure parsing is "
+                    "individually, falling back to `dateutil`. To ensure parsing is "
                     "consistent and as-expected, please specify a format.",
                     UserWarning,
                     stacklevel=find_stack_level(),

pandas/tests/tools/test_to_datetime.py

@@ -3007,11 +3007,9 @@ def test_parsers_dayfirst_yearfirst(
             result2 = Timestamp(date_str)
             assert result2 == expected
 
-        warn = UserWarning if dayfirst else None
-        with tm.assert_produces_warning(warn, match="Could not infer format"):
-            result3 = to_datetime(
-                date_str, dayfirst=dayfirst, yearfirst=yearfirst, cache=cache
-            )
+        result3 = to_datetime(
+            date_str, dayfirst=dayfirst, yearfirst=yearfirst, cache=cache
+        )
 
         result4 = DatetimeIndex([date_str], dayfirst=dayfirst, yearfirst=yearfirst)[0]