Enforce silent downcasting deprecation (pandas-dev#57328)

* Enforce silent downcasting deprecation

* Update

* Update

* Add whatsnew

* Fixup docstrings

* Update

Author: phofl

doc/source/reference/frame.rst

@@ -206,7 +206,6 @@ Missing data handling
 .. autosummary::
    :toctree: api/
 
-   DataFrame.backfill
    DataFrame.bfill
    DataFrame.dropna
    DataFrame.ffill
@@ -216,7 +215,6 @@ Missing data handling
    DataFrame.isnull
    DataFrame.notna
    DataFrame.notnull
-   DataFrame.pad
    DataFrame.replace
 
 Reshaping, sorting, transposing

doc/source/reference/series.rst

@@ -207,7 +207,6 @@ Missing data handling
 .. autosummary::
    :toctree: api/
 
-   Series.backfill
    Series.bfill
    Series.dropna
    Series.ffill
@@ -217,7 +216,6 @@ Missing data handling
    Series.isnull
    Series.notna
    Series.notnull
-   Series.pad
    Series.replace
 
 Reshaping, sorting

doc/source/user_guide/basics.rst

@@ -1308,8 +1308,8 @@ filling method chosen from the following table:
     :header: "Method", "Action"
     :widths: 30, 50
 
-    pad / ffill, Fill values forward
-    bfill / backfill, Fill values backward
+    ffill, Fill values forward
+    bfill, Fill values backward
     nearest, Fill from the nearest index value
 
 We illustrate these fill methods on a simple Series:

doc/source/whatsnew/v2.2.0.rst

@@ -619,6 +619,8 @@ For example:
 
     pd.date_range('2020-01-01', periods=3, freq='QE-NOV')
 
+.. _whatsnew_220.silent_downcasting:
+
 Deprecated automatic downcasting
 ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
 

doc/source/whatsnew/v3.0.0.rst

@@ -107,6 +107,7 @@ Removal of prior version deprecations/changes
 - :func:`read_excel`, :func:`read_json`, :func:`read_html`, and :func:`read_xml` no longer accept raw string or byte representation of the data. That type of data must be wrapped in a :py:class:`StringIO` or :py:class:`BytesIO` (:issue:`53767`)
 - All arguments except the first ``path``-like argument in IO writers are now keyword only (:issue:`54229`)
 - Changed the default value of ``observed`` in :meth:`DataFrame.groupby` and :meth:`Series.groupby` to ``True`` (:issue:`51811`)
+- Enforced silent-downcasting deprecation for :ref:`all relevant methods <whatsnew_220.silent_downcasting>` (:issue:`54710`)
 - Removed ``DataFrame.applymap``, ``Styler.applymap`` and ``Styler.applymap_index`` (:issue:`52364`)
 - Removed ``DataFrame.bool`` and ``Series.bool`` (:issue:`51756`)
 - Removed ``DataFrame.first`` and ``DataFrame.last`` (:issue:`53710`)