Fix new flake8 warnings

3 files changed, 44 insertions, 41 deletions

diff --git a/python/servo/build_commands.py b/python/servo/build_commands.py
index c3a0819ac00..3a4f05729ed 100644
--- a/python/servo/build_commands.py
+++ b/python/servo/build_commands.py
@@ -46,7 +46,7 @@ def notify_linux(title, text):
         notify_obj = bus.get_object("org.freedesktop.Notifications", "/org/freedesktop/Notifications")
         method = notify_obj.get_dbus_method("Notify", "org.freedesktop.Notifications")
         method(title, 0, "", text, "", [], {"transient": True}, -1)
-    except:
+    except ImportError:
         raise Exception("Optional Python module 'dbus' is not installed.")
 
 
@@ -55,7 +55,7 @@ def notify_win(title, text):
         from servo.win32_toast import WindowsToast
         w = WindowsToast()
         w.balloon_tip(title, text)
-    except:
+    except WindowsError:
         from ctypes import Structure, windll, POINTER, sizeof
         from ctypes.wintypes import DWORD, HANDLE, WINFUNCTYPE, BOOL, UINT
 
@@ -920,7 +920,7 @@ def package_gstreamer_dlls(env, servo_exe_dir, target, uwp):
     for gst_lib in gst_dlls:
         try:
             shutil.copy(path.join(gst_root, "bin", gst_lib), servo_exe_dir)
-        except:
+        except FileNotFoundError:
             missing += [str(gst_lib)]
 
     for gst_lib in missing:
@@ -976,7 +976,7 @@ def package_gstreamer_dlls(env, servo_exe_dir, target, uwp):
     for gst_lib in gst_dlls:
         try:
             shutil.copy(path.join(gst_plugin_path, gst_lib), servo_exe_dir)
-        except:
+        except FileNotFoundError:
             missing += [str(gst_lib)]
 
     for gst_lib in missing:
diff --git a/python/servo/command_base.py b/python/servo/command_base.py
index 2fab0d166cc..b84a811c76b 100644
--- a/python/servo/command_base.py
+++ b/python/servo/command_base.py
@@ -487,7 +487,7 @@ class CommandBase(object):
             print("Could not fetch the available nightly versions from the repository : {}".format(
                 e.reason))
             sys.exit(1)
-        except AttributeError as e:
+        except AttributeError:
             print("Could not fetch a nightly version for date {} and platform {}".format(
                 nightly_date, os_prefix))
             sys.exit(1)
@@ -517,8 +517,8 @@ class CommandBase(object):
         else:
             print("The nightly {} does not exist yet, downloading it.".format(
                 destination_file))
-            download_file(destination_file, NIGHTLY_REPOSITORY_URL +
-                          file_to_download, destination_file)
+            download_file(destination_file, NIGHTLY_REPOSITORY_URL
+                          + file_to_download, destination_file)
 
         # Extract the downloaded nightly version
         if os.path.isdir(destination_folder):
@@ -537,7 +537,7 @@ class CommandBase(object):
         try:
             if check_gstreamer_lib():
                 return False
-        except:
+        except subprocess.SubprocessError:
             # Some systems don't have pkg-config; we can't probe in this case
             # and must hope for the best
             return False
@@ -552,7 +552,7 @@ class CommandBase(object):
                 raise Exception("Your system's gstreamer libraries are out of date \
 (we need at least 1.16). Please run ./mach bootstrap-gstreamer")
         else:
-                raise Exception("Your system's gstreamer libraries are out of date \
+            raise Exception("Your system's gstreamer libraries are out of date \
 (we need at least 1.16). If you're unable to \
 install them, let us know by filing a bug!")
         return False
@@ -858,9 +858,9 @@ install them, let us know by filing a bug!")
     def pick_media_stack(self, media_stack, target):
         if not(media_stack):
             if (
-                    not(target) or
-                    ("armv7" in target and "android" in target) or
-                    ("x86_64" in target)
+                    not(target)
+                    or ("armv7" in target and "android" in target)
+                    or ("x86_64" in target)
             ):
                 media_stack = "gstreamer"
             else:
@@ -1032,7 +1032,7 @@ install them, let us know by filing a bug!")
                 print()
                 sys.exit(1)
             raise
-        version = tuple(map(int, re.match(b"rustup (\d+)\.(\d+)\.(\d+)", version_line).groups()))
+        version = tuple(map(int, re.match(br"rustup (\d+)\.(\d+)\.(\d+)", version_line).groups()))
         version_needed = (1, 21, 0)
         if version < version_needed:
             print("rustup is at version %s.%s.%s, Servo requires %s.%s.%s or more recent." % (version + version_needed))
@@ -1069,8 +1069,8 @@ install them, let us know by filing a bug!")
 
 def find_highest_msvc_version_ext():
     def vswhere(args):
-        program_files = (os.environ.get('PROGRAMFILES(X86)') or
-                         os.environ.get('PROGRAMFILES'))
+        program_files = (os.environ.get('PROGRAMFILES(X86)')
+                         or os.environ.get('PROGRAMFILES'))
         if not program_files:
             return []
         vswhere = os.path.join(program_files, 'Microsoft Visual Studio',
@@ -1107,8 +1107,8 @@ def find_highest_msvc_version():
 
     versions = sorted(find_highest_msvc_version_ext(), key=lambda tup: float(tup[1]))
     if not versions:
-        print("Can't find MSBuild.exe installation under %s. Please set the VSINSTALLDIR and VisualStudioVersion" +
-              " environment variables" % base_vs_path)
+        print("Can't find MSBuild.exe installation under %s. Please set the VSINSTALLDIR and VisualStudioVersion"
+              + " environment variables" % base_vs_path)
         sys.exit(1)
     return versions[0]
 
diff --git a/python/tidy/servo_tidy/tidy.py b/python/tidy/servo_tidy/tidy.py
index 9beb0d943cd..1b39970b414 100644
--- a/python/tidy/servo_tidy/tidy.py
+++ b/python/tidy/servo_tidy/tidy.py
@@ -33,10 +33,11 @@ wpt = os.path.join(topdir, "tests", "wpt")
 def wpt_path(*args):
     return os.path.join(wpt, *args)
 
+
 CONFIG_FILE_PATH = os.path.join(".", "servo-tidy.toml")
 WPT_MANIFEST_PATH = wpt_path("include.ini")
 # regex source https://stackoverflow.com/questions/6883049/
-URL_REGEX = re.compile(b'https?://(?:[-\w.]|(?:%[\da-fA-F]{2}))+')
+URL_REGEX = re.compile(br'https?://(?:[-\w.]|(?:%[\da-fA-F]{2}))+')
 
 # Import wptmanifest only when we do have wpt in tree, i.e. we're not
 # inside a Firefox checkout.
@@ -105,8 +106,8 @@ WEBIDL_STANDARDS = [
     b"//github.com/immersive-web/webxr-hands-input/",
     b"//gpuweb.github.io",
     # Not a URL
-    b"// This interface is entirely internal to Servo, and should not be" +
-    b" accessible to\n// web pages."
+    b"// This interface is entirely internal to Servo, and should not be"
+    + b" accessible to\n// web pages."
 ]
 
 
@@ -235,14 +236,14 @@ def check_license(file_name, lines):
     max_blank_lines = 2 if lines[0].startswith(b"#!") else 1
     license_block = []
 
-    for l in lines:
-        l = l.rstrip(b'\n')
-        if not l.strip():
+    for line in lines:
+        line = line.rstrip(b'\n')
+        if not line.strip():
             blank_lines += 1
             if blank_lines >= max_blank_lines:
                 break
             continue
-        line = uncomment(l)
+        line = uncomment(line)
         if line is not None:
             license_block.append(line)
 
@@ -257,7 +258,7 @@ def check_modeline(file_name, lines):
     for idx, line in enumerate(lines[:5]):
         if re.search(b'^.*[ \t](vi:|vim:|ex:)[ \t]', line):
             yield (idx + 1, "vi modeline present")
-        elif re.search(b'-\*-.*-\*-', line, re.IGNORECASE):
+        elif re.search(br'-\*-.*-\*-', line, re.IGNORECASE):
             yield (idx + 1, "emacs file variables present")
 
 
@@ -278,10 +279,10 @@ def contains_url(line):
 
 def is_unsplittable(file_name, line):
     return (
-        contains_url(line) or
-        file_name.endswith(".rs") and
-        line.startswith(b"use ") and
-        b"{" not in line
+        contains_url(line)
+        or file_name.endswith(".rs")
+        and line.startswith(b"use ")
+        and b"{" not in line
     )
 
 
@@ -334,6 +335,7 @@ def check_flake8(file_name, contents):
 
     ignore = {
         "W291",  # trailing whitespace; the standard tidy process will enforce no trailing whitespace
+        "W503",  # linebreak before binary operator; replaced by W504 - linebreak after binary operator
         "E501",  # 80 character line length; the standard tidy process will enforce line length
     }
 
@@ -485,7 +487,7 @@ def check_shell(file_name, lines):
         if " [ " in stripped or stripped.startswith("[ "):
             yield (idx + 1, "script should use `[[` instead of `[` for conditional testing")
 
-        for dollar in re.finditer('\$', stripped):
+        for dollar in re.finditer(r'\$', stripped):
             next_idx = dollar.end()
             if next_idx < len(stripped):
                 next_char = stripped[next_idx]
@@ -605,14 +607,15 @@ def check_rust(file_name, lines):
                 multi_line_string = True
 
         # get rid of comments
-        line = re.sub('//.*?$|/\*.*?$|^\*.*?$', '//', line)
+        line = re.sub(r'//.*?$|/\*.*?$|^\*.*?$', '//', line)
 
         # get rid of attributes that do not contain =
-        line = re.sub('^#[A-Za-z0-9\(\)\[\]_]*?$', '#[]', line)
+        line = re.sub(r'^#[A-Za-z0-9\(\)\[\]_]*?$', '#[]', line)
 
         # flag this line if it matches one of the following regular expressions
         # tuple format: (pattern, format_message, filter_function(match, line))
-        no_filter = lambda match, line: True
+        def no_filter(match, line):
+            return True
         regex_rules = [
             # There should not be any extra pointer dereferencing
             (r": &Vec<", "use &[T] instead of &Vec<T>", no_filter),
@@ -856,16 +859,16 @@ def check_spec(file_name, lines):
     if SPEC_BASE_PATH not in file_name:
         raise StopIteration
     file_name = os.path.relpath(os.path.splitext(file_name)[0], SPEC_BASE_PATH)
-    patt = re.compile("^\s*\/\/.+")
+    patt = re.compile(r"^\s*\/\/.+")
 
     # Pattern representing a line with a macro
-    macro_patt = re.compile("^\s*\S+!(.*)$")
+    macro_patt = re.compile(r"^\s*\S+!(.*)$")
 
     # Pattern representing a line with comment containing a spec link
-    link_patt = re.compile("^\s*///? (<https://.+>|https://.+)$")
+    link_patt = re.compile(r"^\s*///? (<https://.+>|https://.+)$")
 
     # Pattern representing a line with comment or attribute
-    comment_patt = re.compile("^\s*(///?.+|#\[.+\])$")
+    comment_patt = re.compile(r"^\s*(///?.+|#\[.+\])$")
 
     brace_count = 0
     in_impl = False
@@ -931,7 +934,7 @@ def check_config_file(config_file, print_text=True, no_wpt=False):
             continue
 
         # Check for invalid tables
-        if re.match("\[(.*?)\]", line.strip()):
+        if re.match(r"\[(.*?)\]", line.strip()):
             table_name = re.findall(r"\[(.*?)\]", line)[0].strip()
             if table_name not in ("configs", "blocked-packages", "ignore", "check_ext"):
                 yield config_file, idx + 1, "invalid config table [%s]" % table_name
@@ -961,10 +964,10 @@ def check_config_file(config_file, print_text=True, no_wpt=False):
         key = line.split("=")[0].strip()
 
         # Check for invalid keys inside [configs] and [ignore] table
-        if (current_table == "configs" and key not in config or
-                current_table == "ignore" and key not in config["ignore"] or
+        if (current_table == "configs" and key not in config
+                or current_table == "ignore" and key not in config["ignore"]
                 # Any key outside of tables
-                current_table == ""):
+                or current_table == ""):
             yield config_file, idx + 1, "invalid config key '%s'" % key
 
     # Parse config file