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

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)
 

kconfiglib.py

@@ -3926,8 +3926,7 @@ def _open(self, filename, mode):
         # - For Python 3, force the encoding. Forcing the encoding on Python 2
         #   turns strings into Unicode strings, which gets messy. Python 2
         #   doesn't decode regular strings anyway.
-        return open(filename, "rU" if mode == "r" else mode) if _IS_PY2 else \
-               open(filename, mode, encoding=self._encoding)
+        return open(filename, mode, encoding=self._encoding)
 
     def _check_undef_syms(self):
         # Prints warnings for all references to undefined symbols within the
@@ -3956,7 +3955,7 @@ def is_num(s):
 
             return True
 
-        for sym in (self.syms.viewvalues if _IS_PY2 else self.syms.values)():
+        for sym in self.syms.values():
             # - sym.nodes empty means the symbol is undefined (has no
             #   definition locations)
             #
@@ -6896,12 +6895,11 @@ def _shell_fn(kconf, _, command):
         command, shell=True, stdout=subprocess.PIPE, stderr=subprocess.PIPE
     ).communicate()
 
-    if not _IS_PY2:
-        try:
-            stdout = stdout.decode(kconf._encoding)
-            stderr = stderr.decode(kconf._encoding)
-        except UnicodeDecodeError as e:
-            _decoding_error(e, kconf.filename, kconf.linenr)
+    try:
+        stdout = stdout.decode(kconf._encoding)
+        stderr = stderr.decode(kconf._encoding)
+    except UnicodeDecodeError as e:
+        _decoding_error(e, kconf.filename, kconf.linenr)
 
     if stderr:
         kconf._warn("'{}' wrote to stderr: {}".format(
@@ -6938,9 +6936,6 @@ def _shell_fn(kconf, _, command):
 # Symbol will do. We test this with 'is'.
 _NO_CACHED_SELECTION = 0
 
-# Are we running on Python 2?
-_IS_PY2 = sys.version_info[0] < 3
-
 try:
     _UNAME_RELEASE = os.uname()[2]
 except AttributeError:
@@ -7233,11 +7228,11 @@ def _shell_fn(kconf, _, command):
 
 
 def _re_match(regex):
-    return re.compile(regex, 0 if _IS_PY2 else re.ASCII).match
+    return re.compile(regex, re.ASCII).match
 
 
 def _re_search(regex):
-    return re.compile(regex, 0 if _IS_PY2 else re.ASCII).search
+    return re.compile(regex, re.ASCII).search
 
 
 # Various regular expressions used during parsing

menuconfig.py

@@ -989,12 +989,7 @@ def _init():
     # Looking for this in addition to KEY_BACKSPACE (which is unreliable) makes
     # backspace work with TERM=vt100. That makes it likely to work in sane
     # environments.
-    _ERASE_CHAR = curses.erasechar()
-    if sys.version_info[0] >= 3:
-        # erasechar() returns a one-byte bytes object on Python 3. This sets
-        # _ERASE_CHAR to a blank string if it can't be decoded, which should be
-        # harmless.
-        _ERASE_CHAR = _ERASE_CHAR.decode("utf-8", "ignore")
+    _ERASE_CHAR = curses.erasechar().decode("utf-8", "ignore")
 
     _init_styles()
 

oldconfig.py

@@ -32,11 +32,6 @@
 from kconfiglib import Symbol, Choice, BOOL, TRISTATE, HEX, standard_kconfig
 
 
-# Python 2/3 compatibility hack
-if sys.version_info[0] < 3:
-    input = raw_input
-
-
 def _main():
     # Earlier symbols in Kconfig files might depend on later symbols and become
     # visible if their values change. This flag is set to True if the value of

testsuite.py

@@ -2699,16 +2699,12 @@ def verify_bad_argno(name):
 
     sys.path.pop(0)
 
-    # This test can fail on older Python 3.x versions, because they don't
-    # preserve dict insertion order during iteration. The output is still
-    # correct, just different.
-    if not (3, 0) <= sys.version_info <= (3, 5):
-        print("Testing KCONFIG_WARN_UNDEF")
+    print("Testing KCONFIG_WARN_UNDEF")
 
-        os.environ["KCONFIG_WARN_UNDEF"] = "y"
-        c = Kconfig("Kconfiglib/tests/Kundef", warn_to_stderr=False)
+    os.environ["KCONFIG_WARN_UNDEF"] = "y"
+    c = Kconfig("Kconfiglib/tests/Kundef", warn_to_stderr=False)
 
-        verify_equal("\n".join(c.warnings), """
+    verify_equal("\n".join(c.warnings), """
 warning: the int symbol INT (defined at Kconfiglib/tests/Kundef:8) has a non-int range [UNDEF_2 (undefined), 8 (undefined)]
 warning: undefined symbol UNDEF_1:
 
@@ -2747,7 +2743,7 @@ def verify_bad_argno(name):
 	visible if UNDEF_3
 """[1:-1])
 
-        os.environ.pop("KCONFIG_WARN_UNDEF")
+    os.environ.pop("KCONFIG_WARN_UNDEF")
 
 
     print("\nAll selftests passed\n" if all_passed else