Rollup merge of #68947 - chrissimpkins:python-fmt, r=alexcrichton

Python script PEP8 style guide space formatting and minor Python source cleanup

This PR includes the following changes in the Python sources based on a flake8 3.7.9 (mccabe: 0.6.1, pycodestyle: 2.5.0, pyflakes: 2.1.1) CPython 3.7.6 on Darwin lint:

- PEP8 style guide spacing updates *without* line length changes
- removal of unused local variable assignments in context managers and exception handling
- removal of unused Python import statements
- removal of unnecessary semicolons

src/bootstrap/bootstrap.py

@@ -332,7 +332,6 @@ class RustBuild(object):
         self.use_vendored_sources = ''
         self.verbose = False
 
-
     def download_stage0(self):
         """Fetch the build system for Rust, written in Rust
 
@@ -351,7 +350,7 @@ class RustBuild(object):
             try:
                 with tempfile.NamedTemporaryFile(delete=False) as temp_file:
                     temp_path = temp_file.name
-                with tarfile.open(temp_path, "w:xz") as tar:
+                with tarfile.open(temp_path, "w:xz"):
                     pass
                 return True
             except tarfile.CompressionError:

src/bootstrap/configure.py

@@ -399,6 +399,7 @@ def is_number(value):
     except ValueError:
         return False
 
+
 # Here we walk through the constructed configuration we have from the parsed
 # command line arguments. We then apply each piece of configuration by
 # basically just doing a `sed` to change the various configuration line to what

src/ci/cpu-usage-over-time.py

@@ -148,11 +148,11 @@ else:
     print('unknown platform', sys.platform)
     sys.exit(1)
 
-cur_state = State();
+cur_state = State()
 print("Time,Idle")
 while True:
-    time.sleep(1);
-    next_state = State();
+    time.sleep(1)
+    next_state = State()
     now = datetime.datetime.utcnow().isoformat()
     idle = next_state.idle_since(cur_state)
     print("%s,%s" % (now, idle))

src/etc/debugger_pretty_printers_common.py

@@ -212,7 +212,6 @@ class Type(object):
         # REGULAR STRUCT
         return TYPE_KIND_REGULAR_STRUCT
 
-
     def __classify_union(self):
         assert self.get_dwarf_type_kind() == DWARF_TYPE_CODE_UNION
 
@@ -233,7 +232,6 @@ class Type(object):
         else:
             return TYPE_KIND_REGULAR_UNION
 
-
     def __conforms_to_field_layout(self, expected_fields):
         actual_fields = self.get_fields()
         actual_field_count = len(actual_fields)
@@ -363,6 +361,7 @@ def extract_tail_head_ptr_and_cap_from_std_vecdeque(vec_val):
     assert data_ptr.type.get_dwarf_type_kind() == DWARF_TYPE_CODE_PTR
     return (tail, head, data_ptr, capacity)
 
+
 def extract_length_and_ptr_from_slice(slice_val):
     assert (slice_val.type.get_type_kind() == TYPE_KIND_SLICE or
             slice_val.type.get_type_kind() == TYPE_KIND_STR_SLICE)
@@ -376,8 +375,10 @@ def extract_length_and_ptr_from_slice(slice_val):
     assert data_ptr.type.get_dwarf_type_kind() == DWARF_TYPE_CODE_PTR
     return (length, data_ptr)
 
+
 UNQUALIFIED_TYPE_MARKERS = frozenset(["(", "[", "&", "*"])
 
+
 def extract_type_name(qualified_type_name):
     """Extracts the type name from a fully qualified path"""
     if qualified_type_name[0] in UNQUALIFIED_TYPE_MARKERS:
@@ -393,6 +394,7 @@ def extract_type_name(qualified_type_name):
     else:
         return qualified_type_name[index + 2:]
 
+
 try:
     compat_str = unicode  # Python 2
 except NameError:

src/etc/dec2flt_table.py

@@ -14,7 +14,6 @@ is used because (u64, i16) has a ton of padding which would make the table
 even larger, and it's already uncomfortably large (6 KiB).
 """
 from __future__ import print_function
-import sys
 from math import ceil, log
 from fractions import Fraction
 from collections import namedtuple
@@ -82,6 +81,7 @@ def error(f, e, z):
     ulp_err = abs_err / Fraction(2) ** z.exp
     return float(ulp_err)
 
+
 HEADER = """
 //! Tables of approximations of powers of ten.
 //! DO NOT MODIFY: Generated by `src/etc/dec2flt_table.py`

src/etc/gdb_rust_pretty_printing.py

@@ -25,6 +25,7 @@ if _match:
 # GDB Pretty Printing Module for Rust
 # ===============================================================================
 
+
 class GdbType(rustpp.Type):
 
     def __init__(self, ty):
@@ -355,6 +356,7 @@ def children_of_node(boxed_node, height, want_values):
             else:
                 yield keys[i]['value']['value']
 
+
 class RustStdBTreeSetPrinter(object):
     def __init__(self, val):
         self.__val = val
@@ -429,6 +431,7 @@ class RustOsStringPrinter(object):
     def display_hint(self):
         return "string"
 
+
 class RustCStyleVariantPrinter(object):
     def __init__(self, val):
         assert val.type.get_dwarf_type_kind() == rustpp.DWARF_TYPE_CODE_ENUM

src/etc/generate-deriving-span-tests.py

@@ -8,7 +8,8 @@ derives have spans that point to the fields, rather than the
 sample usage: src/etc/generate-deriving-span-tests.py
 """
 
-import os, stat
+import os
+import stat
 
 TEST_DIR = os.path.abspath(
     os.path.join(os.path.dirname(__file__), '../test/ui/derives/'))
@@ -56,6 +57,7 @@ struct Struct(
 
 ENUM_TUPLE, ENUM_STRUCT, STRUCT_FIELDS, STRUCT_TUPLE = range(4)
 
+
 def create_test_case(type, trait, super_traits, error_count):
     string = [ENUM_STRING, ENUM_STRUCT_VARIANT_STRING, STRUCT_STRING, STRUCT_TUPLE_STRING][type]
     all_traits = ','.join([trait] + super_traits)
@@ -66,6 +68,7 @@ def create_test_case(type, trait, super_traits, error_count):
     code = string.format(traits=all_traits, errors=errors)
     return TEMPLATE.format(error_deriving=error_deriving, code=code)
 
+
 def write_file(name, string):
     test_file = os.path.join(TEST_DIR, 'derives-span-%s.rs' % name)
 

src/etc/generate-keyword-tests.py

@@ -11,7 +11,6 @@ sample usage: src/etc/generate-keyword-tests.py as break
 
 import sys
 import os
-import datetime
 import stat
 
 

src/etc/htmldocck.py

@@ -131,6 +131,7 @@ try:
 except NameError:
     unichr = chr
 
+
 class CustomHTMLParser(HTMLParser):
     """simplified HTML parser.
 
@@ -169,14 +170,18 @@ class CustomHTMLParser(HTMLParser):
         HTMLParser.close(self)
         return self.__builder.close()
 
+
 Command = namedtuple('Command', 'negated cmd args lineno context')
 
+
 class FailedCheck(Exception):
     pass
 
+
 class InvalidCheck(Exception):
     pass
 
+
 def concat_multi_lines(f):
     """returns a generator out of the file object, which
     - removes `\\` then `\n` then a shared prefix with the previous line then
@@ -208,6 +213,7 @@ def concat_multi_lines(f):
     if lastline is not None:
         print_err(lineno, line, 'Trailing backslash at the end of the file')
 
+
 LINE_PATTERN = re.compile(r'''
     (?<=(?<!\S)@)(?P<negated>!?)
     (?P<cmd>[A-Za-z]+(?:-[A-Za-z]+)*)
@@ -353,7 +359,7 @@ def check_tree_text(tree, path, pat, regexp):
                 ret = check_string(value, pat, regexp)
                 if ret:
                     break
-    except Exception as e:
+    except Exception:
         print('Failed to get path "{}"'.format(path))
         raise
     return ret
@@ -363,6 +369,7 @@ def get_tree_count(tree, path):
     path = normalize_xpath(path)
     return len(tree.findall(path))
 
+
 def stderr(*args):
     if sys.version_info.major < 3:
         file = codecs.getwriter('utf-8')(sys.stderr)
@@ -371,6 +378,7 @@ def stderr(*args):
 
     print(*args, file=file)
 
+
 def print_err(lineno, context, err, message=None):
     global ERR_COUNT
     ERR_COUNT += 1
@@ -381,8 +389,10 @@ def print_err(lineno, context, err, message=None):
     if context:
         stderr("\t{}".format(context))
 
+
 ERR_COUNT = 0
 
+
 def check_command(c, cache):
     try:
         cerr = ""
@@ -448,11 +458,13 @@ def check_command(c, cache):
     except InvalidCheck as err:
         print_err(c.lineno, c.context, str(err))
 
+
 def check(target, commands):
     cache = CachedFiles(target)
     for c in commands:
         check_command(c, cache)
 
+
 if __name__ == '__main__':
     if len(sys.argv) != 3:
         stderr('Usage: {} <doc dir> <template>'.format(sys.argv[0]))

src/etc/lldb_batchmode.py

@@ -157,6 +157,7 @@ def start_watchdog():
 # ~main
 ####################################################################################################
 
+
 if len(sys.argv) != 3:
     print("usage: python lldb_batchmode.py target-path script-path")
     sys.exit(1)

src/etc/lldb_rust_formatters.py

@@ -1,11 +1,11 @@
 import lldb
-import re
 import debugger_pretty_printers_common as rustpp
 
 # ===============================================================================
 # LLDB Pretty Printing Module for Rust
 # ===============================================================================
 
+
 class LldbType(rustpp.Type):
 
     def __init__(self, ty):
@@ -157,9 +157,9 @@ def print_val(lldb_val, internal_dict):
     return lldb_val.GetValue()
 
 
-#=--------------------------------------------------------------------------------------------------
+# =---------------------------------------------------------------------------------------
 # Type-Specialized Printing Functions
-#=--------------------------------------------------------------------------------------------------
+# =---------------------------------------------------------------------------------------
 
 def print_struct_val(val, internal_dict, omit_first_field, omit_type_name, is_tuple_like):
     """
@@ -212,6 +212,7 @@ def print_struct_val(val, internal_dict, omit_first_field, omit_type_name, is_tu
     return template % {"type_name": type_name,
                        "body": body}
 
+
 def print_pointer_val(val, internal_dict):
     """Prints a pointer value with Rust syntax"""
     assert val.type.get_dwarf_type_kind() == rustpp.DWARF_TYPE_CODE_PTR
@@ -253,18 +254,21 @@ def print_std_vec_val(val, internal_dict):
                                               length,
                                               internal_dict)
 
+
 def print_str_slice_val(val, internal_dict):
     (length, data_ptr) = rustpp.extract_length_and_ptr_from_slice(val)
     return read_utf8_string(data_ptr, length)
 
+
 def print_std_string_val(val, internal_dict):
     vec = val.get_child_at_index(0)
     (length, data_ptr, cap) = rustpp.extract_length_ptr_and_cap_from_std_vec(vec)
     return read_utf8_string(data_ptr, length)
 
-#=--------------------------------------------------------------------------------------------------
+# =-----------------------------------------------------------------------
 # Helper Functions
-#=--------------------------------------------------------------------------------------------------
+# =-----------------------------------------------------------------------
+
 
 def print_array_of_values(array_name, data_ptr_val, length, internal_dict):
     """Prints a contiguous memory range, interpreting it as values of the

src/tools/publish_toolstate.py

@@ -1,11 +1,11 @@
 #!/usr/bin/env python
 # -*- coding: utf-8 -*-
 
-## This script publishes the new "current" toolstate in the toolstate repo (not to be
-## confused with publishing the test results, which happens in
-## `src/ci/docker/x86_64-gnu-tools/checktools.sh`).
-## It is set as callback for `src/ci/docker/x86_64-gnu-tools/repo.sh` by the CI scripts
-## when a new commit lands on `master` (i.e., after it passed all checks on `auto`).
+# This script publishes the new "current" toolstate in the toolstate repo (not to be
+# confused with publishing the test results, which happens in
+# `src/ci/docker/x86_64-gnu-tools/checktools.sh`).
+# It is set as callback for `src/ci/docker/x86_64-gnu-tools/repo.sh` by the CI scripts
+# when a new commit lands on `master` (i.e., after it passed all checks on `auto`).
 
 from __future__ import print_function
 
@@ -103,6 +103,7 @@ def validate_maintainers(repo, github_token):
         print("The build will fail due to this.")
         exit(1)
 
+
 def read_current_status(current_commit, path):
     '''Reads build status of `current_commit` from content of `history/*.tsv`
     '''
@@ -113,14 +114,17 @@ def read_current_status(current_commit, path):
                 return json.loads(status)
     return {}
 
+
 def gh_url():
     return os.environ['TOOLSTATE_ISSUES_API_URL']
 
+
 def maybe_delink(message):
     if os.environ.get('TOOLSTATE_SKIP_MENTIONS') is not None:
         return message.replace("@", "")
     return message
 
+
 def issue(
     tool,
     status,
@@ -164,6 +168,7 @@ def issue(
     ))
     response.read()
 
+
 def update_latest(
     current_commit,
     relevant_pr_number,