gh-136355: Deprecate -b and -bb CLI flags in 3.15

Doc/c-api/init_config.rst

@@ -1278,6 +1278,10 @@ PyConfig
 
       Default: ``0``.
 
+      .. deprecated:: 3.15
+
+         Deprecated, will become no-op in 3.17.
+
    .. c:member:: int warn_default_encoding
 
       If non-zero, emit a :exc:`EncodingWarning` warning when :class:`io.TextIOWrapper`

Doc/using/cmdline.rst

@@ -254,6 +254,15 @@ Miscellaneous options
    .. versionchanged:: 3.5
       Affects also comparisons of :class:`bytes` with :class:`int`.
 
+   .. deprecated-removed:: 3.15 3.17
+
+      Deprecate :option:`-b` and :option:`!-bb`
+      and schedule them to become no-op in Python 3.17.
+      These were primarily helpers for the Python 2 -> 3 transition.
+      Starting with Python 3.17, no :exc:`BytesWarning` will be raised
+      for these cases; use a type checker instead.
+
+
 .. option:: -B
 
    If given, Python won't try to write ``.pyc`` files on the

Doc/whatsnew/3.15.rst

@@ -537,6 +537,17 @@ module_name
 Deprecated
 ==========
 
+CLI
+---
+
+* Deprecate :option:`-b` and :option:`!-bb`
+  and schedule them to become no-op in Python 3.17.
+  These were primarily helpers for the Python 2 -> 3 transition.
+  Starting with Python 3.17, no :exc:`BytesWarning` will be raised
+  for these cases; use a type checker instead.
+
+  (Contributed by Nikita Sobolev in :gh:`136355`.)
+
 hashlib
 -------
 

Misc/NEWS.d/next/Core_and_Builtins/2025-07-07-12-24-00.gh-issue-136355.MTcA8j.rst

@@ -0,0 +1,2 @@
+Deprecate :option:`-b` and :option:`!-bb` and schedule them
+to become no-op in Python 3.17.

Python/initconfig.c

@@ -256,6 +256,7 @@ static const char usage_help[] = "\
 Options (and corresponding environment variables):\n\
 -b     : issue warnings about converting bytes/bytearray to str and comparing\n\
          bytes/bytearray with str or bytes with int. (-bb: issue errors)\n\
+         deprecated since 3.15 and will become no-op in 3.17.\n\
 -B     : don't write .pyc files on import; also PYTHONDONTWRITEBYTECODE=x\n\
 -c cmd : program passed in as string (terminates option list)\n\
 -d     : turn on parser debugging output (for experts only, only works on\n\