bpo-33710: Deprecate l*gettext() and related functions in the gettext module. (GH-10139)

They return encoded bytes and are Python 2 artifacts.
diff --git a/Lib/gettext.py b/Lib/gettext.py
index 4c3b80b..920742c 100644
--- a/Lib/gettext.py
+++ b/Lib/gettext.py
@@ -274,8 +274,14 @@
         return message
 
     def lgettext(self, message):
+        import warnings
+        warnings.warn('lgettext() is deprecated, use gettext() instead',
+                      DeprecationWarning, 2)
         if self._fallback:
-            return self._fallback.lgettext(message)
+            with warnings.catch_warnings():
+                warnings.filterwarnings('ignore', r'.*\blgettext\b.*',
+                                        DeprecationWarning)
+                return self._fallback.lgettext(message)
         if self._output_charset:
             return message.encode(self._output_charset)
         return message.encode(locale.getpreferredencoding())
@@ -289,8 +295,14 @@
             return msgid2
 
     def lngettext(self, msgid1, msgid2, n):
+        import warnings
+        warnings.warn('lngettext() is deprecated, use ngettext() instead',
+                      DeprecationWarning, 2)
         if self._fallback:
-            return self._fallback.lngettext(msgid1, msgid2, n)
+            with warnings.catch_warnings():
+                warnings.filterwarnings('ignore', r'.*\blngettext\b.*',
+                                        DeprecationWarning)
+                return self._fallback.lngettext(msgid1, msgid2, n)
         if n == 1:
             tmsg = msgid1
         else:
@@ -306,9 +318,15 @@
         return self._charset
 
     def output_charset(self):
+        import warnings
+        warnings.warn('output_charset() is deprecated',
+                      DeprecationWarning, 2)
         return self._output_charset
 
     def set_output_charset(self, charset):
+        import warnings
+        warnings.warn('set_output_charset() is deprecated',
+                      DeprecationWarning, 2)
         self._output_charset = charset
 
     def install(self, names=None):
@@ -424,6 +442,9 @@
             transidx += 8
 
     def lgettext(self, message):
+        import warnings
+        warnings.warn('lgettext() is deprecated, use gettext() instead',
+                      DeprecationWarning, 2)
         missing = object()
         tmsg = self._catalog.get(message, missing)
         if tmsg is missing:
@@ -435,6 +456,9 @@
         return tmsg.encode(locale.getpreferredencoding())
 
     def lngettext(self, msgid1, msgid2, n):
+        import warnings
+        warnings.warn('lngettext() is deprecated, use ngettext() instead',
+                      DeprecationWarning, 2)
         try:
             tmsg = self._catalog[(msgid1, self.plural(n))]
         except KeyError:
@@ -510,9 +534,10 @@
 
 # a mapping between absolute .mo file path and Translation object
 _translations = {}
+_unspecified = ['unspecified']
 
 def translation(domain, localedir=None, languages=None,
-                class_=None, fallback=False, codeset=None):
+                class_=None, fallback=False, codeset=_unspecified):
     if class_ is None:
         class_ = GNUTranslations
     mofiles = find(domain, localedir, languages, all=True)
@@ -538,8 +563,15 @@
         # are not used.
         import copy
         t = copy.copy(t)
-        if codeset:
-            t.set_output_charset(codeset)
+        if codeset is not _unspecified:
+            import warnings
+            warnings.warn('parameter codeset is deprecated',
+                          DeprecationWarning, 2)
+            if codeset:
+                with warnings.catch_warnings():
+                    warnings.filterwarnings('ignore', r'.*\bset_output_charset\b.*',
+                                            DeprecationWarning)
+                    t.set_output_charset(codeset)
         if result is None:
             result = t
         else:
@@ -547,7 +579,7 @@
     return result
 
 
-def install(domain, localedir=None, codeset=None, names=None):
+def install(domain, localedir=None, codeset=_unspecified, names=None):
     t = translation(domain, localedir, fallback=True, codeset=codeset)
     t.install(names)
 
@@ -576,6 +608,9 @@
 
 
 def bind_textdomain_codeset(domain, codeset=None):
+    import warnings
+    warnings.warn('bind_textdomain_codeset() is deprecated',
+                  DeprecationWarning, 2)
     global _localecodesets
     if codeset is not None:
         _localecodesets[domain] = codeset
@@ -584,24 +619,31 @@
 
 def dgettext(domain, message):
     try:
-        t = translation(domain, _localedirs.get(domain, None),
-                        codeset=_localecodesets.get(domain))
+        t = translation(domain, _localedirs.get(domain, None))
     except OSError:
         return message
     return t.gettext(message)
 
 def ldgettext(domain, message):
+    import warnings
+    warnings.warn('ldgettext() is deprecated, use dgettext() instead',
+                  DeprecationWarning, 2)
     codeset = _localecodesets.get(domain)
     try:
-        t = translation(domain, _localedirs.get(domain, None), codeset=codeset)
+        with warnings.catch_warnings():
+            warnings.filterwarnings('ignore', r'.*\bparameter codeset\b.*',
+                                    DeprecationWarning)
+            t = translation(domain, _localedirs.get(domain, None), codeset=codeset)
     except OSError:
         return message.encode(codeset or locale.getpreferredencoding())
-    return t.lgettext(message)
+    with warnings.catch_warnings():
+        warnings.filterwarnings('ignore', r'.*\blgettext\b.*',
+                                DeprecationWarning)
+        return t.lgettext(message)
 
 def dngettext(domain, msgid1, msgid2, n):
     try:
-        t = translation(domain, _localedirs.get(domain, None),
-                        codeset=_localecodesets.get(domain))
+        t = translation(domain, _localedirs.get(domain, None))
     except OSError:
         if n == 1:
             return msgid1
@@ -610,28 +652,49 @@
     return t.ngettext(msgid1, msgid2, n)
 
 def ldngettext(domain, msgid1, msgid2, n):
+    import warnings
+    warnings.warn('ldngettext() is deprecated, use dngettext() instead',
+                  DeprecationWarning, 2)
     codeset = _localecodesets.get(domain)
     try:
-        t = translation(domain, _localedirs.get(domain, None), codeset=codeset)
+        with warnings.catch_warnings():
+            warnings.filterwarnings('ignore', r'.*\bparameter codeset\b.*',
+                                    DeprecationWarning)
+            t = translation(domain, _localedirs.get(domain, None), codeset=codeset)
     except OSError:
         if n == 1:
             tmsg = msgid1
         else:
             tmsg = msgid2
         return tmsg.encode(codeset or locale.getpreferredencoding())
-    return t.lngettext(msgid1, msgid2, n)
+    with warnings.catch_warnings():
+        warnings.filterwarnings('ignore', r'.*\blngettext\b.*',
+                                DeprecationWarning)
+        return t.lngettext(msgid1, msgid2, n)
 
 def gettext(message):
     return dgettext(_current_domain, message)
 
 def lgettext(message):
-    return ldgettext(_current_domain, message)
+    import warnings
+    warnings.warn('lgettext() is deprecated, use gettext() instead',
+                  DeprecationWarning, 2)
+    with warnings.catch_warnings():
+        warnings.filterwarnings('ignore', r'.*\bldgettext\b.*',
+                                DeprecationWarning)
+        return ldgettext(_current_domain, message)
 
 def ngettext(msgid1, msgid2, n):
     return dngettext(_current_domain, msgid1, msgid2, n)
 
 def lngettext(msgid1, msgid2, n):
-    return ldngettext(_current_domain, msgid1, msgid2, n)
+    import warnings
+    warnings.warn('lngettext() is deprecated, use ngettext() instead',
+                  DeprecationWarning, 2)
+    with warnings.catch_warnings():
+        warnings.filterwarnings('ignore', r'.*\bldngettext\b.*',
+                                DeprecationWarning)
+        return ldngettext(_current_domain, msgid1, msgid2, n)
 
 # dcgettext() has been deemed unnecessary and is not implemented.
 
diff --git a/Lib/test/test_gettext.py b/Lib/test/test_gettext.py
index b5ed05e..bbad102 100644
--- a/Lib/test/test_gettext.py
+++ b/Lib/test/test_gettext.py
@@ -1,5 +1,6 @@
 import os
 import base64
+import contextlib
 import gettext
 import locale
 import unittest
@@ -461,116 +462,174 @@
         GettextBaseTest.setUp(self)
         self.mofile = MOFILE
 
+    @contextlib.contextmanager
+    def assertDeprecated(self, name):
+        with self.assertWarnsRegex(DeprecationWarning,
+                                   fr'^{name}\(\) is deprecated'):
+            yield
+
     def test_lgettext(self):
         lgettext = gettext.lgettext
         ldgettext = gettext.ldgettext
-        self.assertEqual(lgettext('mullusk'), b'bacon')
-        self.assertEqual(lgettext('spam'), b'spam')
-        self.assertEqual(ldgettext('gettext', 'mullusk'), b'bacon')
-        self.assertEqual(ldgettext('gettext', 'spam'), b'spam')
+        with self.assertDeprecated('lgettext'):
+            self.assertEqual(lgettext('mullusk'), b'bacon')
+        with self.assertDeprecated('lgettext'):
+            self.assertEqual(lgettext('spam'), b'spam')
+        with self.assertDeprecated('ldgettext'):
+            self.assertEqual(ldgettext('gettext', 'mullusk'), b'bacon')
+        with self.assertDeprecated('ldgettext'):
+            self.assertEqual(ldgettext('gettext', 'spam'), b'spam')
 
     def test_lgettext_2(self):
         with open(self.mofile, 'rb') as fp:
             t = gettext.GNUTranslations(fp)
         lgettext = t.lgettext
-        self.assertEqual(lgettext('mullusk'), b'bacon')
-        self.assertEqual(lgettext('spam'), b'spam')
+        with self.assertDeprecated('lgettext'):
+            self.assertEqual(lgettext('mullusk'), b'bacon')
+        with self.assertDeprecated('lgettext'):
+            self.assertEqual(lgettext('spam'), b'spam')
 
     def test_lgettext_bind_textdomain_codeset(self):
         lgettext = gettext.lgettext
         ldgettext = gettext.ldgettext
-        saved_codeset = gettext.bind_textdomain_codeset('gettext')
+        with self.assertDeprecated('bind_textdomain_codeset'):
+            saved_codeset = gettext.bind_textdomain_codeset('gettext')
         try:
-            gettext.bind_textdomain_codeset('gettext', 'utf-16')
-            self.assertEqual(lgettext('mullusk'), 'bacon'.encode('utf-16'))
-            self.assertEqual(lgettext('spam'), 'spam'.encode('utf-16'))
-            self.assertEqual(ldgettext('gettext', 'mullusk'), 'bacon'.encode('utf-16'))
-            self.assertEqual(ldgettext('gettext', 'spam'), 'spam'.encode('utf-16'))
+            with self.assertDeprecated('bind_textdomain_codeset'):
+                gettext.bind_textdomain_codeset('gettext', 'utf-16')
+            with self.assertDeprecated('lgettext'):
+                self.assertEqual(lgettext('mullusk'), 'bacon'.encode('utf-16'))
+            with self.assertDeprecated('lgettext'):
+                self.assertEqual(lgettext('spam'), 'spam'.encode('utf-16'))
+            with self.assertDeprecated('ldgettext'):
+                self.assertEqual(ldgettext('gettext', 'mullusk'), 'bacon'.encode('utf-16'))
+            with self.assertDeprecated('ldgettext'):
+                self.assertEqual(ldgettext('gettext', 'spam'), 'spam'.encode('utf-16'))
         finally:
             del gettext._localecodesets['gettext']
-            gettext.bind_textdomain_codeset('gettext', saved_codeset)
+            with self.assertDeprecated('bind_textdomain_codeset'):
+                gettext.bind_textdomain_codeset('gettext', saved_codeset)
 
     def test_lgettext_output_encoding(self):
         with open(self.mofile, 'rb') as fp:
             t = gettext.GNUTranslations(fp)
         lgettext = t.lgettext
-        t.set_output_charset('utf-16')
-        self.assertEqual(lgettext('mullusk'), 'bacon'.encode('utf-16'))
-        self.assertEqual(lgettext('spam'), 'spam'.encode('utf-16'))
+        with self.assertDeprecated('set_output_charset'):
+            t.set_output_charset('utf-16')
+        with self.assertDeprecated('lgettext'):
+            self.assertEqual(lgettext('mullusk'), 'bacon'.encode('utf-16'))
+        with self.assertDeprecated('lgettext'):
+            self.assertEqual(lgettext('spam'), 'spam'.encode('utf-16'))
 
     def test_lngettext(self):
         lngettext = gettext.lngettext
         ldngettext = gettext.ldngettext
-        x = lngettext('There is %s file', 'There are %s files', 1)
+        with self.assertDeprecated('lngettext'):
+            x = lngettext('There is %s file', 'There are %s files', 1)
         self.assertEqual(x, b'Hay %s fichero')
-        x = lngettext('There is %s file', 'There are %s files', 2)
+        with self.assertDeprecated('lngettext'):
+            x = lngettext('There is %s file', 'There are %s files', 2)
         self.assertEqual(x, b'Hay %s ficheros')
-        x = lngettext('There is %s directory', 'There are %s directories', 1)
+        with self.assertDeprecated('lngettext'):
+            x = lngettext('There is %s directory', 'There are %s directories', 1)
         self.assertEqual(x, b'There is %s directory')
-        x = lngettext('There is %s directory', 'There are %s directories', 2)
+        with self.assertDeprecated('lngettext'):
+            x = lngettext('There is %s directory', 'There are %s directories', 2)
         self.assertEqual(x, b'There are %s directories')
-        x = ldngettext('gettext', 'There is %s file', 'There are %s files', 1)
+        with self.assertDeprecated('ldngettext'):
+            x = ldngettext('gettext', 'There is %s file', 'There are %s files', 1)
         self.assertEqual(x, b'Hay %s fichero')
-        x = ldngettext('gettext', 'There is %s file', 'There are %s files', 2)
+        with self.assertDeprecated('ldngettext'):
+            x = ldngettext('gettext', 'There is %s file', 'There are %s files', 2)
         self.assertEqual(x, b'Hay %s ficheros')
-        x = ldngettext('gettext', 'There is %s directory', 'There are %s directories', 1)
+        with self.assertDeprecated('ldngettext'):
+            x = ldngettext('gettext', 'There is %s directory', 'There are %s directories', 1)
         self.assertEqual(x, b'There is %s directory')
-        x = ldngettext('gettext', 'There is %s directory', 'There are %s directories', 2)
+        with self.assertDeprecated('ldngettext'):
+            x = ldngettext('gettext', 'There is %s directory', 'There are %s directories', 2)
         self.assertEqual(x, b'There are %s directories')
 
     def test_lngettext_2(self):
         with open(self.mofile, 'rb') as fp:
             t = gettext.GNUTranslations(fp)
         lngettext = t.lngettext
-        x = lngettext('There is %s file', 'There are %s files', 1)
+        with self.assertDeprecated('lngettext'):
+            x = lngettext('There is %s file', 'There are %s files', 1)
         self.assertEqual(x, b'Hay %s fichero')
-        x = lngettext('There is %s file', 'There are %s files', 2)
+        with self.assertDeprecated('lngettext'):
+            x = lngettext('There is %s file', 'There are %s files', 2)
         self.assertEqual(x, b'Hay %s ficheros')
-        x = lngettext('There is %s directory', 'There are %s directories', 1)
+        with self.assertDeprecated('lngettext'):
+            x = lngettext('There is %s directory', 'There are %s directories', 1)
         self.assertEqual(x, b'There is %s directory')
-        x = lngettext('There is %s directory', 'There are %s directories', 2)
+        with self.assertDeprecated('lngettext'):
+            x = lngettext('There is %s directory', 'There are %s directories', 2)
         self.assertEqual(x, b'There are %s directories')
 
     def test_lngettext_bind_textdomain_codeset(self):
         lngettext = gettext.lngettext
         ldngettext = gettext.ldngettext
-        saved_codeset = gettext.bind_textdomain_codeset('gettext')
+        with self.assertDeprecated('bind_textdomain_codeset'):
+            saved_codeset = gettext.bind_textdomain_codeset('gettext')
         try:
-            gettext.bind_textdomain_codeset('gettext', 'utf-16')
-            x = lngettext('There is %s file', 'There are %s files', 1)
+            with self.assertDeprecated('bind_textdomain_codeset'):
+                gettext.bind_textdomain_codeset('gettext', 'utf-16')
+            with self.assertDeprecated('lngettext'):
+                x = lngettext('There is %s file', 'There are %s files', 1)
             self.assertEqual(x, 'Hay %s fichero'.encode('utf-16'))
-            x = lngettext('There is %s file', 'There are %s files', 2)
+            with self.assertDeprecated('lngettext'):
+                x = lngettext('There is %s file', 'There are %s files', 2)
             self.assertEqual(x, 'Hay %s ficheros'.encode('utf-16'))
-            x = lngettext('There is %s directory', 'There are %s directories', 1)
+            with self.assertDeprecated('lngettext'):
+                x = lngettext('There is %s directory', 'There are %s directories', 1)
             self.assertEqual(x, 'There is %s directory'.encode('utf-16'))
-            x = lngettext('There is %s directory', 'There are %s directories', 2)
+            with self.assertDeprecated('lngettext'):
+                x = lngettext('There is %s directory', 'There are %s directories', 2)
             self.assertEqual(x, 'There are %s directories'.encode('utf-16'))
-            x = ldngettext('gettext', 'There is %s file', 'There are %s files', 1)
+            with self.assertDeprecated('ldngettext'):
+                x = ldngettext('gettext', 'There is %s file', 'There are %s files', 1)
             self.assertEqual(x, 'Hay %s fichero'.encode('utf-16'))
-            x = ldngettext('gettext', 'There is %s file', 'There are %s files', 2)
+            with self.assertDeprecated('ldngettext'):
+                x = ldngettext('gettext', 'There is %s file', 'There are %s files', 2)
             self.assertEqual(x, 'Hay %s ficheros'.encode('utf-16'))
-            x = ldngettext('gettext', 'There is %s directory', 'There are %s directories', 1)
+            with self.assertDeprecated('ldngettext'):
+                x = ldngettext('gettext', 'There is %s directory', 'There are %s directories', 1)
             self.assertEqual(x, 'There is %s directory'.encode('utf-16'))
-            x = ldngettext('gettext', 'There is %s directory', 'There are %s directories', 2)
+            with self.assertDeprecated('ldngettext'):
+                x = ldngettext('gettext', 'There is %s directory', 'There are %s directories', 2)
             self.assertEqual(x, 'There are %s directories'.encode('utf-16'))
         finally:
             del gettext._localecodesets['gettext']
-            gettext.bind_textdomain_codeset('gettext', saved_codeset)
+            with self.assertDeprecated('bind_textdomain_codeset'):
+                gettext.bind_textdomain_codeset('gettext', saved_codeset)
 
     def test_lngettext_output_encoding(self):
         with open(self.mofile, 'rb') as fp:
             t = gettext.GNUTranslations(fp)
         lngettext = t.lngettext
-        t.set_output_charset('utf-16')
-        x = lngettext('There is %s file', 'There are %s files', 1)
+        with self.assertDeprecated('set_output_charset'):
+            t.set_output_charset('utf-16')
+        with self.assertDeprecated('lngettext'):
+            x = lngettext('There is %s file', 'There are %s files', 1)
         self.assertEqual(x, 'Hay %s fichero'.encode('utf-16'))
-        x = lngettext('There is %s file', 'There are %s files', 2)
+        with self.assertDeprecated('lngettext'):
+            x = lngettext('There is %s file', 'There are %s files', 2)
         self.assertEqual(x, 'Hay %s ficheros'.encode('utf-16'))
-        x = lngettext('There is %s directory', 'There are %s directories', 1)
+        with self.assertDeprecated('lngettext'):
+            x = lngettext('There is %s directory', 'There are %s directories', 1)
         self.assertEqual(x, 'There is %s directory'.encode('utf-16'))
-        x = lngettext('There is %s directory', 'There are %s directories', 2)
+        with self.assertDeprecated('lngettext'):
+            x = lngettext('There is %s directory', 'There are %s directories', 2)
         self.assertEqual(x, 'There are %s directories'.encode('utf-16'))
 
+    def test_output_encoding(self):
+        with open(self.mofile, 'rb') as fp:
+            t = gettext.GNUTranslations(fp)
+        with self.assertDeprecated('set_output_charset'):
+            t.set_output_charset('utf-16')
+        with self.assertDeprecated('output_charset'):
+            self.assertEqual(t.output_charset(), 'utf-16')
+
 
 class GNUTranslationParsingTest(GettextBaseTest):
     def test_plural_form_error_issue17898(self):
@@ -642,6 +701,16 @@
         self.assertEqual(len(gettext._translations), 2)
         self.assertEqual(t.__class__, DummyGNUTranslations)
 
+        # Test deprecated parameter codeset
+        with self.assertWarnsRegex(DeprecationWarning, 'parameter codeset'):
+            t = gettext.translation('gettext', self.localedir,
+                                    class_=DummyGNUTranslations,
+                                    codeset='utf-16')
+        self.assertEqual(len(gettext._translations), 2)
+        self.assertEqual(t.__class__, DummyGNUTranslations)
+        with self.assertWarns(DeprecationWarning):
+            self.assertEqual(t.output_charset(), 'utf-16')
+
 
 class MiscTestCase(unittest.TestCase):
     def test__all__(self):
@@ -649,11 +718,8 @@
         support.check__all__(self, gettext, blacklist=blacklist)
 
 
-def test_main():
-    support.run_unittest(__name__)
-
 if __name__ == '__main__':
-    test_main()
+    unittest.main()
 
 
 # For reference, here's the .po file used to created the GNU_MO_DATA above.