convert_strftime_format argument target is now mandatory to avoid…

… mistakes

pandas/_libs/tslib.pyx

@@ -189,7 +189,7 @@ def format_array_from_datetime(
             else:
                 try:
                     # Try to get the string formatting template for this format
-                    str_format, loc_s = convert_strftime_format(format)
+                    str_format, loc_s = convert_strftime_format(format, target="datetime")
                 except UnsupportedStrFmtDirective:
                     # Unsupported directive: fallback to standard `strftime`
                     fast_strftime = False

pandas/_libs/tslibs/period.pyx

@@ -2360,7 +2360,8 @@ cdef class _Period(PeriodMixin):
     def fast_strftime(self, fmt_str: str, loc_s: object) -> str:
         """A faster alternative to `strftime` using string formatting.
 
-        `fmt_str` and `loc_s` should be created using `convert_strftime_format(fmt)`.
+        `fmt_str` and `loc_s` should be created using
+        `convert_strftime_format(fmt, target="period")`.
 
         See also `self.strftime`, that relies on `period_format`.
 

pandas/_libs/tslibs/strftime.py

@@ -127,7 +127,7 @@ def get_current_locale_specific_string() -> LocaleSpecificDtStrings:
 
 def convert_strftime_format(
     strftime_fmt: str,
-    target: str = "datetime",
+    target: str,
     new_style_fmt: bool = False,
 ) -> Tuple[str, LocaleSpecificDtStrings]:
     """Convert a strftime formatting string into a formatting template string.

pandas/_libs/tslibs/timestamps.pyx

@@ -1435,15 +1435,16 @@ class Timestamp(_Timestamp):
     def fast_strftime(self, fmt_str: str, loc_s: object) -> str:
         """A faster alternative to `strftime` using string formatting.
 
-        `fmt_str` and `loc_s` should be created using `convert_strftime_format(fmt)`.
+        `fmt_str` and `loc_s` should be created using
+        `convert_strftime_format(fmt, target="datetime")`.
 
         See also `self.strftime`, that relies on `datetime.strftime`.
 
         Examples
         --------
         >>> from pandas._libs.tslibs import convert_strftime_format
         >>> ts = pd.Timestamp('2020-03-14T15:32:52.192548651')
-        >>> fmt, loc_s = convert_strftime_format('%Y-%m-%dT%H:%M:%S')
+        >>> fmt, loc_s = convert_strftime_format('%Y-%m-%dT%H:%M:%S', target="datetime")
         >>> ts.fast_strftime(fmt, loc_s)
         '2020-03-14T15:32:52'
         """

pandas/io/formats/format.py

@@ -1822,7 +1822,8 @@ def get_format_datetime64(
         if date_format is not None and fast_strftime:
             try:
                 # Try to get the string formatting template for this format
-                str_date_fmt, loc_s = convert_strftime_format(date_format)
+                str_date_fmt, loc_s = convert_strftime_format(date_format,
+                                                              target="datetime")
             except UnsupportedStrFmtDirective:
                 # Unsupported directive: fallback to standard `strftime`
                 pass