sapling/edenscm
Jun Wu d678fe1702 encoding: replace 'ascii' with 'utf-8' automatically
Summary:
`ascii` was used as the default / fallback, which is not a user-friendly choice.
Nowadays utf-8 dominates:

- Rust stdlib is utf-8.
- Ruby since 1.9 is utf-8 by default.
- Python 3 is unicode by default.
- Windows 10 adds utf-8 code page.

Given the fact that:

- Our CI sets HGENCODING to utf-8
- Nuclide passes `--encoding=utf-8` to every command.
- Some people have messed up with `LC_*` and complained about hg crashes.
- utf-8 is a super set of ascii, nobody complains that they want `ascii`
  encoding and the `utf-8` encoding messed their setup up.

Let's just use `utf-8` as the default encoding. More aggressively, if someone
sets `ascii` as the encoding, it's almost always a mistake. Auto-correct that
to `utf-8` too.

This should also make future integration with Rust easier (where it's enforced
utf-8 and does not have an option to change the encoding). In the future we
might just drop the flexibility of choosing customized encoding, so this diff
autofixes `ascii` to `utf-8`, instead of allowing `ascii` to be set. We cannot
enforce `utf-8` yet, because of Windows.

Here is our encoding strategy vs the upstream's:

| item           | upstream |          | ours          | ours  |
|                | current  | ideal    | current       | ideal |
| CLI argv       | bytes    | bytes    | utf-8 [1]     | utf-8 |
| path           | bytes    | auto [3] | migrating [2] | utf-8 |
| commit message | utf-8    | utf-8    | utf-8         | utf-8 |
| bookmark name  | utf-8    | utf-8    | utf-8         | utf-8 |
| file content   | bytes    | bytes    | bytes         | bytes |

[1]: Argv was accidentally enforced utf-8 for command-line arguments by a Rust
wrapper.  But it simplified a lot of things and is kind of ok: everything that
can be passed as CLI arguments are utf-8: -M commit message, -b bookmark, paths,
etc. There is no "file content" passed via CLI arguments.

[2]: Path is controversial, because it's possible for systems to have non-utf8
paths. The upstream behavior is incorrect if a repo gets shared among different
encoding systems (ex. both Linux and Windows). We have to know the encoding of
paths to be able to convert them suitable for the local system. One way is to
enforce UTF-8 for paths. The other is to keep encoding information stored with
individual paths (like Ruby strings). The UTF-8 approach is much simpler with
the tradeoff that non-utf-8 paths become unsupported, which seems to be a
reasonable trade-off.

[3]: See https://www.mercurial-scm.org/wiki/WindowsUTF8Plan.

Reviewed By: singhsrb

Differential Revision: D17098991

fbshipit-source-id: c0ff1e586a887233bd43cdb854fb3538aa9b70c2
2019-09-12 15:06:36 -07:00
..
hgdemandimport demandimport: make sqlite3 non-lazy 2019-08-19 12:26:21 -07:00
hgext graphql: do not try to parse commit info if it is not a dict 2019-09-12 10:40:51 -07:00
mercurial encoding: replace 'ascii' with 'utf-8' automatically 2019-09-12 15:06:36 -07:00
__init__.py edenscm: move sys.path handling to top-level edenscm 2019-07-25 17:43:41 -07:00