drop support for Python 2.x as it is very much EOL

A follow-up to b96a5ad where we stopped
having CI run tests on Python 2.x. This actually drops the few remaining
Python 2.x compatibility bits as Python 2.x has EOL'd a long time ago.

Signed-off-by: Benjamin Cabé <benjamin@zephyrproject.org>

Author: kartben

README.rst

@@ -33,7 +33,7 @@ Overview
 
 Kconfiglib is a `Kconfig
 <https://github.com/torvalds/linux/blob/master/Documentation/kbuild/kconfig-language.rst>`__
-implementation in Python 2/3. It started out as a helper library, but now has a
+implementation in Python 3. It started out as a helper library, but now has a
 enough functionality to also work well as a standalone Kconfig implementation
 (including `terminal and GUI menuconfig interfaces <Menuconfig interfaces_>`_
 and `Kconfig extensions`_).
@@ -121,9 +121,7 @@ available in the C tools.
 the configuration and (optionally) information that can be used to rebuild only
 files that reference Kconfig symbols that have changed value.
 
-Starting with Kconfiglib version 12.2.0, all utilities are compatible with both
-Python 2 and Python 3. Previously, ``menuconfig.py`` only ran under Python 3
-(i.e., it's now more backwards compatible than before).
+All utilities run under Python 3.
 
 **Note:** If you install Kconfiglib with ``pip``'s ``--user`` flag, make sure
 that your ``PATH`` includes the directory where the executables end up. You can
@@ -164,18 +162,16 @@ Installation for the Linux kernel
 
 See the module docstring at the top of `kconfiglib.py <https://github.com/zephyrproject-rtos/Kconfiglib/blob/master/kconfiglib.py>`_.
 
-Python version compatibility (2.7/3.2+)
-~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+Python version compatibility
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~
 
-Kconfiglib and all utilities run under both Python 2.7 and Python 3.2 and
-later. The code mostly uses basic Python features and has no third-party
-dependencies, so keeping it backwards-compatible is pretty low effort.
+Kconfiglib and all utilities run under Python 3.9 and later. The code mostly
+uses basic Python features and has no third-party dependencies.
 
 The 3.2 requirement comes from ``argparse``. ``format()`` with unnumbered
 ``{}`` is used as well.
 
-A recent Python 3 version is recommended if you have a choice, as it'll give
-you better Unicode handling.
+A recent Python 3 version is recommended for better Unicode handling.
 
 Getting started
 ---------------
@@ -502,9 +498,9 @@ Other features
 
 - **Windows support**
 
-  Nothing Linux-specific is used. Universal newlines mode is used for both
-  Python 2 and Python 3.
-  
+  Nothing Linux-specific is used. Universal newlines mode is used for
+  interoperability between Linux and Windows.
+
   The `Zephyr <https://www.zephyrproject.org/>`_ project uses Kconfiglib to
   generate ``.config`` files and C headers on Linux as well as Windows.
 
@@ -562,16 +558,15 @@ Three configuration interfaces are currently available:
   the terminal menuconfig. Only this mode distinguishes between symbols defined
   with ``config`` and symbols defined with ``menuconfig``.
 
-  ``guiconfig.py`` has been tested on X11, Windows, and macOS, and is
-  compatible with both Python 2 and Python 3.
+  ``guiconfig.py`` has been tested on X11, Windows, and macOS.
 
   Despite being part of the Python standard library, ``tkinter`` often isn't
   included by default in Python installations on Linux. These commands will
   install it on a few different distributions:
 
-  - Ubuntu: ``sudo apt install python-tk``/``sudo apt install python3-tk``
+  - Ubuntu: ``sudo apt install python3-tk``
 
-  - Fedora: ``dnf install python2-tkinter``/``dnf install python3-tkinter``
+  - Fedora: ``dnf install python3-tkinter``
 
   - Arch: ``sudo pacman -S tk``
 
@@ -591,10 +586,6 @@ Three configuration interfaces are currently available:
   I did my best with the images, but some are definitely only art adjacent.
   Touch-ups are welcome. :)
 
-- `pymenuconfig <https://github.com/RomaVis/pymenuconfig>`_, built by `RomaVis
-  <https://github.com/RomaVis>`_, is an older portable Python 2/3 TkInter
-  menuconfig implementation.
-
   Screenshot below:
 
   .. image:: https://raw.githubusercontent.com/RomaVis/pymenuconfig/master/screenshot.PNG
@@ -784,7 +775,7 @@ configurations generated by the C tools, for a number of cases. See
 for the available options.
 
 The `tests/reltest <https://github.com/zephyrproject-rtos/Kconfiglib/blob/master/tests/reltest>`_ script runs the test suite
-and all the example scripts for both Python 2 and Python 3, verifying that everything works.
+and all the example scripts, verifying that everything works.
 
 Rarely, the output from the C tools is changed slightly (most recently due to a
 `change <https://www.spinics.net/lists/linux-kbuild/msg17074.html>`_ I added).

examples/menuconfig_example.py

@@ -130,11 +130,6 @@
                        TRI_TO_STR
 
 
-# Python 2/3 compatibility hack
-if sys.version_info[0] < 3:
-    input = raw_input
-
-
 def indent_print(s, indent):
     print(indent*" " + s)
 

genconfig.py

@@ -131,24 +131,15 @@ def main():
         kconf.sync_deps(args.sync_deps)
 
     if args.file_list is not None:
-        with _open_write(args.file_list) as f:
+        with open(args.file_list, "w", encoding="utf-8") as f:
             for path in kconf.kconfig_filenames:
                 f.write(path + "\n")
 
     if args.env_list is not None:
-        with _open_write(args.env_list) as f:
+        with open(args.env_list, "w", encoding="utf-8") as f:
             for env_var in kconf.env_vars:
                 f.write("{}={}\n".format(env_var, os.environ[env_var]))
 
 
-def _open_write(path):
-    # Python 2/3 compatibility. io.open() is available on both, but makes
-    # write() expect 'unicode' strings on Python 2.
-
-    if sys.version_info[0] < 3:
-        return open(path, "w")
-    return open(path, "w", encoding="utf-8")
-
-
 if __name__ == "__main__":
     main()

guiconfig.py

@@ -9,7 +9,7 @@
 
 A Tkinter-based menuconfig implementation, based around a treeview control and
 a help display. The interface should feel familiar to people used to qconf
-('make xconfig'). Compatible with both Python 2 and Python 3.
+('make xconfig').
 
 The display can be toggled between showing the full tree and showing just a
 single menu (like menuconfig.py). Only single-menu mode distinguishes between
@@ -55,23 +55,11 @@
 import errno
 import os
 import re
-import sys
-
-_PY2 = sys.version_info[0] < 3
-
-if _PY2:
-    # Python 2
-    from Tkinter import *
-    import ttk
-    import tkFont as font
-    import tkFileDialog as filedialog
-    import tkMessageBox as messagebox
-else:
-    # Python 3
-    from tkinter import *
-    import tkinter.ttk as ttk
-    import tkinter.font as font
-    from tkinter import filedialog, messagebox
+
+from tkinter import *
+import tkinter.ttk as ttk
+import tkinter.font as font
+from tkinter import filedialog, messagebox
 
 from kconfiglib import Symbol, Choice, MENU, COMMENT, MenuNode, \
                        BOOL, TRISTATE, STRING, INT, HEX, \
@@ -395,8 +383,7 @@ def _init_misc_ui():
     # Does misc. UI initialization, like setting the title, icon, and theme
 
     _root.title(_kconf.mainmenu_text)
-    # iconphoto() isn't available in Python 2's Tkinter
-    _root.tk.call("wm", "iconphoto", _root._w, "-default", _icon_img)
+    _root.iconphoto(True, _icon_img)
     # Reducing the width of the window to 1 pixel makes it move around, at
     # least on GNOME. Prevent weird stuff like that.
     _root.minsize(128, 128)
@@ -514,9 +501,7 @@ def tree_select(_):
             desc["state"] = "disabled"
             return
 
-        # Text.replace() is not available in Python 2's Tkinter
-        desc.delete("1.0", "end")
-        desc.insert("end", _info_str(_id_to_node[sel[0]]))
+        desc.replace("1.0", "end", _info_str(_id_to_node[sel[0]]))
 
         desc["state"] = "disabled"
 
@@ -1118,11 +1103,6 @@ def _change_node(node, parent):
     if sc.type in (INT, HEX, STRING):
         s = _set_val_dialog(node, parent)
 
-        # Tkinter can return 'unicode' strings on Python 2, which Kconfiglib
-        # can't deal with. UTF-8-encode the string to work around it.
-        if _PY2 and isinstance(s, unicode):
-            s = s.encode("utf-8", "ignore")
-
         if s is not None:
             _set_val(sc, s)
 
@@ -1174,9 +1154,10 @@ def _set_val_dialog(node, parent):
     # Pops up a dialog for setting the value of the string/int/hex
     # symbol at node 'node'. 'parent' is the parent window.
 
+    _entry_res = None
+
     def ok(_=None):
-        # No 'nonlocal' in Python 2
-        global _entry_res
+        nonlocal _entry_res
 
         s = entry.get()
         if sym.type == HEX and not s.startswith(("0x", "0X")):
@@ -1187,7 +1168,7 @@ def ok(_=None):
             dialog.destroy()
 
     def cancel(_=None):
-        global _entry_res
+        nonlocal _entry_res
         _entry_res = None
         dialog.destroy()