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
A python hook for "hg fix" that prints out the number of files and revisions
that were affected, along with which fixer tools were applied. Also checks how
many times it sees a specific key generated by one of the fixer tools defined
below.
$ cat >> $TESTTMP/postfixhook.py <<EOF
> import collections
> def file(ui, repo, rev=None, path=b'', metadata=None, **kwargs):
> ui.status(b'fixed %s in revision %d using %s\n' %
> (path, rev, b', '.join(metadata.keys())))
> def summarize(ui, repo, replacements=None, wdirwritten=False,
> metadata=None, **kwargs):
> counts = collections.defaultdict(int)
> keys = 0
> for fixername, metadatalist in metadata.items():
> for metadata in metadatalist:
> if metadata is None:
> continue
> counts[fixername] += 1
> if 'key' in metadata:
> keys += 1
> ui.status(b'saw "key" %d times\n' % (keys,))
> for name, count in sorted(counts.items()):
> ui.status(b'fixed %d files with %s\n' % (count, name))
> if replacements:
> ui.status(b'fixed %d revisions\n' % (len(replacements),))
> if wdirwritten:
> ui.status(b'fixed the working copy\n')
> EOF
Some mock output for fixer tools that demonstrate what could go wrong with
expecting the metadata output format.
$ printf 'new content\n' > $TESTTMP/missing
$ printf 'not valid json\0new content\n' > $TESTTMP/invalid
$ printf '{"key": "value"}\0new content\n' > $TESTTMP/valid
Configure some fixer tools based on the output defined above, and enable the
hooks defined above. Disable parallelism to make output of the parallel file
processing phase stable.
$ cat >> $HGRCPATH <<EOF
> [extensions]
> fix =
> [fix]
> missing:command=cat $TESTTMP/missing
> missing:pattern=missing
> missing:metadata=true
> invalid:command=cat $TESTTMP/invalid
> invalid:pattern=invalid
> invalid:metadata=true
> valid:command=cat $TESTTMP/valid
> valid:pattern=valid
> valid:metadata=true
> [hooks]
> postfixfile = python:$TESTTMP/postfixhook.py:file
> postfix = python:$TESTTMP/postfixhook.py:summarize
> [worker]
> enabled=false
> EOF
See what happens when we execute each of the fixer tools. Some print warnings,
some write back to the file.
$ hg init repo
$ cd repo
$ printf "old content\n" > invalid
$ printf "old content\n" > missing
$ printf "old content\n" > valid
$ hg add -q
$ hg fix -w
ignored invalid output from fixer tool: invalid
ignored invalid output from fixer tool: missing
fixed valid in revision 2147483647 using valid
saw "key" 1 times
fixed 1 files with valid
fixed the working copy
$ cat missing invalid valid
old content
old content
new content
$ cd ..