rust: switch hg-core and hg-cpython to rust 2018 edition
Many interesting changes have happened in Rust since the Oxidation Plan was
introduced, like the 2018 edition and procedural macros:
- Opting in to the 2018 edition is a clear benefit in terms of future
proofing, new (nice to have) syntactical sugar notwithstanding. It
also has a new non-lexical, non-AST based borrow checker that has
fewer bugs(!) and allows us to write correct code that in some cases
would have been rejected by the old one.
- Procedural macros allow us to use the PyO3 crate which maintainers have
expressed the clear goal of compiling on stable, which would help in
code maintainability compared to rust-cpython.
In this patch are the following changes:
- Removing most `extern crate` uses
- Updating `use` clauses (`crate` keyword, nested `use`)
- Removing `mod.rs` in favor of an aptly named module file
Like discussed in the mailing list (
https://www.mercurial-scm.org/pipermail/mercurial-devel/2019-July/132316.html
), until Rust integration in Mercurial is considered to be out of the
experimental phase, the maximum version of Rust allowed is whatever the latest
version Debian packages.
Differential Revision: https://phab.mercurial-scm.org/D6597
#!/usr/bin/env python
"""Test the running system for features availability. Exit with zero
if all features are there, non-zero otherwise. If a feature name is
prefixed with "no-", the absence of feature is tested.
"""
from __future__ import absolute_import, print_function
import hghave
import optparse
import os
import sys
checks = hghave.checks
def list_features():
for name, feature in sorted(checks.items()):
desc = feature[1]
print(name + ':', desc)
def test_features():
failed = 0
for name, feature in checks.items():
check, _ = feature
try:
check()
except Exception as e:
print("feature %s failed: %s" % (name, e))
failed += 1
return failed
parser = optparse.OptionParser("%prog [options] [features]")
parser.add_option("--test-features", action="store_true",
help="test available features")
parser.add_option("--list-features", action="store_true",
help="list available features")
def _loadaddon():
if 'TESTDIR' in os.environ:
# loading from '.' isn't needed, because `hghave` should be
# running at TESTTMP in this case
path = os.environ['TESTDIR']
else:
path = '.'
if not os.path.exists(os.path.join(path, 'hghaveaddon.py')):
return
sys.path.insert(0, path)
try:
import hghaveaddon
assert hghaveaddon # silence pyflakes
except BaseException as inst:
sys.stderr.write('failed to import hghaveaddon.py from %r: %s\n'
% (path, inst))
sys.exit(2)
sys.path.pop(0)
if __name__ == '__main__':
options, args = parser.parse_args()
_loadaddon()
if options.list_features:
list_features()
sys.exit(0)
if options.test_features:
sys.exit(test_features())
hghave.require(args)