[cleanup] Upgrade syntax

Using https://github.com/asottile/pyupgrade

1. `__future__` imports and `coding: utf-8` were removed
2. Files were rewritten with `pyupgrade --py36-plus --keep-percent-format`
3. f-strings were cherry-picked from `pyupgrade --py36-plus`

Extractors are left untouched (except removing header) to avoid unnecessary merge conflicts

15 files changed, 25 insertions, 57 deletions

diff --git a/yt_dlp/downloader/__init__.py b/yt_dlp/downloader/__init__.py
index 96d484dee..f5abfd5df 100644
--- a/yt_dlp/downloader/__init__.py
+++ b/yt_dlp/downloader/__init__.py
@@ -1,5 +1,3 @@
-from __future__ import unicode_literals
-
 from ..compat import compat_str
 from ..utils import (
     determine_protocol,
diff --git a/yt_dlp/downloader/common.py b/yt_dlp/downloader/common.py
index cbfea7a65..d42539931 100644
--- a/yt_dlp/downloader/common.py
+++ b/yt_dlp/downloader/common.py
@@ -1,5 +1,3 @@
-from __future__ import division, unicode_literals
-
 import os
 import re
 import time
@@ -25,7 +23,7 @@ from ..minicurses import (
 )
 
 
-class FileDownloader(object):
+class FileDownloader:
     """File Downloader class.
 
     File downloader objects are the ones responsible of downloading the
@@ -219,7 +217,7 @@ class FileDownloader(object):
                 while True:
                     try:
                         return func(self, *args, **kwargs)
-                    except (IOError, OSError) as err:
+                    except OSError as err:
                         retry = retry + 1
                         if retry > file_access_retries or err.errno not in (errno.EACCES, errno.EINVAL):
                             if not fatal:
@@ -486,4 +484,4 @@ class FileDownloader(object):
         if exe is None:
             exe = os.path.basename(str_args[0])
 
-        self.write_debug('%s command line: %s' % (exe, shell_quote(str_args)))
+        self.write_debug(f'{exe} command line: {shell_quote(str_args)}')
diff --git a/yt_dlp/downloader/dash.py b/yt_dlp/downloader/dash.py
index a845ee7d3..64eb5e66a 100644
--- a/yt_dlp/downloader/dash.py
+++ b/yt_dlp/downloader/dash.py
@@ -1,4 +1,3 @@
-from __future__ import unicode_literals
 import time
 
 from ..downloader import get_suitable_downloader
@@ -46,7 +45,7 @@ class DashSegmentsFD(FragmentFD):
 
             if real_downloader:
                 self.to_screen(
-                    '[%s] Fragment downloads will be delegated to %s' % (self.FD_NAME, real_downloader.get_basename()))
+                    f'[{self.FD_NAME}] Fragment downloads will be delegated to {real_downloader.get_basename()}')
                 info_dict['fragments'] = list(fragments_to_download)
                 fd = real_downloader(self.ydl, self.params)
                 return fd.real_download(filename, info_dict)
diff --git a/yt_dlp/downloader/external.py b/yt_dlp/downloader/external.py
index 71af705ea..b6dd32701 100644
--- a/yt_dlp/downloader/external.py
+++ b/yt_dlp/downloader/external.py
@@ -1,5 +1,3 @@
-from __future__ import unicode_literals
-
 import os.path
 import re
 import subprocess
@@ -56,7 +54,7 @@ class ExternalFD(FragmentFD):
             }
             if filename != '-':
                 fsize = os.path.getsize(encodeFilename(tmpfilename))
-                self.to_screen('\r[%s] Downloaded %s bytes' % (self.get_basename(), fsize))
+                self.to_screen(f'\r[{self.get_basename()}] Downloaded {fsize} bytes')
                 self.try_rename(tmpfilename, filename)
                 status.update({
                     'downloaded_bytes': fsize,
@@ -157,7 +155,7 @@ class ExternalFD(FragmentFD):
             fragment_filename = '%s-Frag%d' % (tmpfilename, frag_index)
             try:
                 src, _ = self.sanitize_open(fragment_filename, 'rb')
-            except IOError as err:
+            except OSError as err:
                 if skip_unavailable_fragments and frag_index > 1:
                     self.report_skip_fragment(frag_index, err)
                     continue
@@ -179,7 +177,7 @@ class CurlFD(ExternalFD):
         cmd = [self.exe, '--location', '-o', tmpfilename, '--compressed']
         if info_dict.get('http_headers') is not None:
             for key, val in info_dict['http_headers'].items():
-                cmd += ['--header', '%s: %s' % (key, val)]
+                cmd += ['--header', f'{key}: {val}']
 
         cmd += self._bool_option('--continue-at', 'continuedl', '-', '0')
         cmd += self._valueless_option('--silent', 'noprogress')
@@ -216,7 +214,7 @@ class AxelFD(ExternalFD):
         cmd = [self.exe, '-o', tmpfilename]
         if info_dict.get('http_headers') is not None:
             for key, val in info_dict['http_headers'].items():
-                cmd += ['-H', '%s: %s' % (key, val)]
+                cmd += ['-H', f'{key}: {val}']
         cmd += self._configuration_args()
         cmd += ['--', info_dict['url']]
         return cmd
@@ -229,7 +227,7 @@ class WgetFD(ExternalFD):
         cmd = [self.exe, '-O', tmpfilename, '-nv', '--no-cookies', '--compression=auto']
         if info_dict.get('http_headers') is not None:
             for key, val in info_dict['http_headers'].items():
-                cmd += ['--header', '%s: %s' % (key, val)]
+                cmd += ['--header', f'{key}: {val}']
         cmd += self._option('--limit-rate', 'ratelimit')
         retry = self._option('--tries', 'retries')
         if len(retry) == 2:
@@ -240,7 +238,7 @@ class WgetFD(ExternalFD):
         proxy = self.params.get('proxy')
         if proxy:
             for var in ('http_proxy', 'https_proxy'):
-                cmd += ['--execute', '%s=%s' % (var, proxy)]
+                cmd += ['--execute', f'{var}={proxy}']
         cmd += self._valueless_option('--no-check-certificate', 'nocheckcertificate')
         cmd += self._configuration_args()
         cmd += ['--', info_dict['url']]
@@ -271,7 +269,7 @@ class Aria2cFD(ExternalFD):
 
         if info_dict.get('http_headers') is not None:
             for key, val in info_dict['http_headers'].items():
-                cmd += ['--header', '%s: %s' % (key, val)]
+                cmd += ['--header', f'{key}: {val}']
         cmd += self._option('--max-overall-download-limit', 'ratelimit')
         cmd += self._option('--interface', 'source_address')
         cmd += self._option('--all-proxy', 'proxy')
@@ -289,10 +287,10 @@ class Aria2cFD(ExternalFD):
         dn = os.path.dirname(tmpfilename)
         if dn:
             if not os.path.isabs(dn):
-                dn = '.%s%s' % (os.path.sep, dn)
+                dn = f'.{os.path.sep}{dn}'
             cmd += ['--dir', dn + os.path.sep]
         if 'fragments' not in info_dict:
-            cmd += ['--out', '.%s%s' % (os.path.sep, os.path.basename(tmpfilename))]
+            cmd += ['--out', f'.{os.path.sep}{os.path.basename(tmpfilename)}']
         cmd += ['--auto-file-renaming=false']
 
         if 'fragments' in info_dict:
@@ -320,7 +318,7 @@ class HttpieFD(ExternalFD):
 
         if info_dict.get('http_headers') is not None:
             for key, val in info_dict['http_headers'].items():
-                cmd += ['%s:%s' % (key, val)]
+                cmd += [f'{key}:{val}']
         return cmd
 
 
@@ -393,7 +391,7 @@ class FFmpegFD(ExternalFD):
             headers = handle_youtubedl_headers(info_dict['http_headers'])
             args += [
                 '-headers',
-                ''.join('%s: %s\r\n' % (key, val) for key, val in headers.items())]
+                ''.join(f'{key}: {val}\r\n' for key, val in headers.items())]
 
         env = None
         proxy = self.params.get('proxy')
diff --git a/yt_dlp/downloader/f4m.py b/yt_dlp/downloader/f4m.py
index 0008b7c28..414071075 100644
--- a/yt_dlp/downloader/f4m.py
+++ b/yt_dlp/downloader/f4m.py
@@ -1,5 +1,3 @@
-from __future__ import division, unicode_literals
-
 import io
 import itertools
 import time
diff --git a/yt_dlp/downloader/fc2.py b/yt_dlp/downloader/fc2.py
index 157bcf23e..d503aac04 100644
--- a/yt_dlp/downloader/fc2.py
+++ b/yt_dlp/downloader/fc2.py
@@ -1,5 +1,3 @@
-from __future__ import division, unicode_literals
-
 import threading
 
 from .common import FileDownloader
diff --git a/yt_dlp/downloader/fragment.py b/yt_dlp/downloader/fragment.py
index c45a8a476..217b89e3f 100644
--- a/yt_dlp/downloader/fragment.py
+++ b/yt_dlp/downloader/fragment.py
@@ -1,5 +1,3 @@
-from __future__ import division, unicode_literals
-
 import http.client
 import json
 import math
@@ -172,8 +170,7 @@ class FragmentFD(FileDownloader):
                 total_frags_str += ' (not including %d ad)' % ad_frags
         else:
             total_frags_str = 'unknown (live)'
-        self.to_screen(
-            '[%s] Total fragments: %s' % (self.FD_NAME, total_frags_str))
+        self.to_screen(f'[{self.FD_NAME}] Total fragments: {total_frags_str}')
         self.report_destination(ctx['filename'])
         dl = HttpQuietDownloader(
             self.ydl,
@@ -342,8 +339,7 @@ class FragmentFD(FileDownloader):
                 total_frags_str += ' (not including %d ad)' % ad_frags
         else:
             total_frags_str = 'unknown (live)'
-        self.to_screen(
-            '[%s] Total fragments: %s' % (self.FD_NAME, total_frags_str))
+        self.to_screen(f'[{self.FD_NAME}] Total fragments: {total_frags_str}')
 
         tmpfilename = self.temp_name(ctx['filename'])
 
diff --git a/yt_dlp/downloader/hls.py b/yt_dlp/downloader/hls.py
index e932fd6ae..00695f93f 100644
--- a/yt_dlp/downloader/hls.py
+++ b/yt_dlp/downloader/hls.py
@@ -1,5 +1,3 @@
-from __future__ import unicode_literals
-
 import re
 import io
 import binascii
@@ -102,8 +100,7 @@ class HlsFD(FragmentFD):
         if real_downloader and not real_downloader.supports_manifest(s):
             real_downloader = None
         if real_downloader:
-            self.to_screen(
-                '[%s] Fragment downloads will be delegated to %s' % (self.FD_NAME, real_downloader.get_basename()))
+            self.to_screen(f'[{self.FD_NAME}] Fragment downloads will be delegated to {real_downloader.get_basename()}')
 
         def is_ad_fragment_start(s):
             return (s.startswith('#ANVATO-SEGMENT-INFO') and 'type=ad' in s
diff --git a/yt_dlp/downloader/http.py b/yt_dlp/downloader/http.py
index a232168fa..03efbf1cd 100644
--- a/yt_dlp/downloader/http.py
+++ b/yt_dlp/downloader/http.py
@@ -1,5 +1,3 @@
-from __future__ import unicode_literals
-
 import os
 import ssl
 import time
@@ -221,10 +219,12 @@ class HttpFD(FileDownloader):
                 min_data_len = self.params.get('min_filesize')
                 max_data_len = self.params.get('max_filesize')
                 if min_data_len is not None and data_len < min_data_len:
-                    self.to_screen('\r[download] File is smaller than min-filesize (%s bytes < %s bytes). Aborting.' % (data_len, min_data_len))
+                    self.to_screen(
+                        f'\r[download] File is smaller than min-filesize ({data_len} bytes < {min_data_len} bytes). Aborting.')
                     return False
                 if max_data_len is not None and data_len > max_data_len:
-                    self.to_screen('\r[download] File is larger than max-filesize (%s bytes > %s bytes). Aborting.' % (data_len, max_data_len))
+                    self.to_screen(
+                        f'\r[download] File is larger than max-filesize ({data_len} bytes > {max_data_len} bytes). Aborting.')
                     return False
 
             byte_counter = 0 + ctx.resume_len
@@ -265,7 +265,7 @@ class HttpFD(FileDownloader):
                         assert ctx.stream is not None
                         ctx.filename = self.undo_temp_name(ctx.tmpfilename)
                         self.report_destination(ctx.filename)
-                    except (OSError, IOError) as err:
+                    except OSError as err:
                         self.report_error('unable to open for writing: %s' % str(err))
                         return False
 
@@ -277,7 +277,7 @@ class HttpFD(FileDownloader):
 
                 try:
                     ctx.stream.write(data_block)
-                except (IOError, OSError) as err:
+                except OSError as err:
                     self.to_stderr('\n')
                     self.report_error('unable to write data: %s' % str(err))
                     return False
diff --git a/yt_dlp/downloader/ism.py b/yt_dlp/downloader/ism.py
index 2ba36085e..ca4ca3a19 100644
--- a/yt_dlp/downloader/ism.py
+++ b/yt_dlp/downloader/ism.py
@@ -1,5 +1,3 @@
-from __future__ import unicode_literals
-
 import time
 import binascii
 import io
diff --git a/yt_dlp/downloader/mhtml.py b/yt_dlp/downloader/mhtml.py
index 54e711792..5a322f1db 100644
--- a/yt_dlp/downloader/mhtml.py
+++ b/yt_dlp/downloader/mhtml.py
@@ -1,6 +1,3 @@
-# coding: utf-8
-from __future__ import unicode_literals
-
 import io
 import quopri
 import re
diff --git a/yt_dlp/downloader/niconico.py b/yt_dlp/downloader/niconico.py
index 521dfece3..0e6c177b7 100644
--- a/yt_dlp/downloader/niconico.py
+++ b/yt_dlp/downloader/niconico.py
@@ -1,6 +1,3 @@
-# coding: utf-8
-from __future__ import unicode_literals
-
 import threading
 
 from .common import FileDownloader
diff --git a/yt_dlp/downloader/rtmp.py b/yt_dlp/downloader/rtmp.py
index 90f1acfd4..12aa04cf3 100644
--- a/yt_dlp/downloader/rtmp.py
+++ b/yt_dlp/downloader/rtmp.py
@@ -1,5 +1,3 @@
-from __future__ import unicode_literals
-
 import os
 import re
 import subprocess
diff --git a/yt_dlp/downloader/rtsp.py b/yt_dlp/downloader/rtsp.py
index 7815d59d9..26dbd9ef7 100644
--- a/yt_dlp/downloader/rtsp.py
+++ b/yt_dlp/downloader/rtsp.py
@@ -1,5 +1,3 @@
-from __future__ import unicode_literals
-
 import os
 import subprocess
 
@@ -32,7 +30,7 @@ class RtspFD(FileDownloader):
         retval = subprocess.call(args)
         if retval == 0:
             fsize = os.path.getsize(encodeFilename(tmpfilename))
-            self.to_screen('\r[%s] %s bytes' % (args[0], fsize))
+            self.to_screen(f'\r[{args[0]}] {fsize} bytes')
             self.try_rename(tmpfilename, filename)
             self._hook_progress({
                 'downloaded_bytes': fsize,
diff --git a/yt_dlp/downloader/youtube_live_chat.py b/yt_dlp/downloader/youtube_live_chat.py
index cfca686ee..36c82b03b 100644
--- a/yt_dlp/downloader/youtube_live_chat.py
+++ b/yt_dlp/downloader/youtube_live_chat.py
@@ -1,5 +1,3 @@
-from __future__ import division, unicode_literals
-
 import json
 import time