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Differential D8321

darwin: use vim, not vi, to avoid data-loss inducing posix behavior
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Authored by spectral on Mar 23 2020, 6:12 PM.

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rHGc23877cb25a5: darwin: use vim, not vi, to avoid data-loss inducing posix behavior
Summary

Apple's version of vim, available at
opensource.apple.com/release/macos-1015.html (for Catalina, but this behavior
has been there for a while) has several tweaks from the version of vim from
vim.org. Most of these tweaks appear to be for "Unix2003" compatibility.

One of the tweaks is that if any ex command raises an error, the entire
process will (when you exit, possibly minutes/hours later) also exit non-zero.
Ex commands are things like :foo.

Luckily, they only enabled this if vim was executed (via a symlink or copying
the binary) as vi or ex. If you start it as vim, it doesn't have this
behavior, so let's do that.

To see this in action, run the following two commands on macOS:

$ vi -c ':unknown' -c ':qa' ; echo $?
1
$ vim -c ':unknown' -c ':qa' ; echo $?
0

We don't want to start ignoring non-zero return types from the editor because
that will mean you can't use :cquit to intentionally exit 1 (which,
shows up as 2 if you combine an ex command error and a cquit, but only a 1 if
you just use cquit, so we can't differentiate between the two statuses). Since
we can't differentiate, we have to assume that all non-zero exit codes are
intentional and an indication of the user's desire to not continue with whatever
we're doing. If this was a complicated hg split or hg histedit, this is
especially disastrous :(

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Event Timeline

spectral created this revision.Mar 23 2020, 6:12 PM
spectral added a commit: rHGc23877cb25a5: darwin: use vim, not vi, to avoid data-loss inducing posix behavior.Mar 25 2020, 12:53 PM
This revision was not accepted when it landed; it landed in state Needs Review.
Closed by commit rHGc23877cb25a5: darwin: use vim, not vi, to avoid data-loss inducing posix behavior (authored by spectral). · Explain Why
This revision was automatically updated to reflect the committed changes.

Revision Contents
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PathPackages
Mmercurial/ui.py (6 lines)

Diff 20877

mercurial/ui.py

def geteditor(self): def geteditor(self):
'''return editor to use''' '''return editor to use'''
if pycompat.sysplatform == b'plan9': if pycompat.sysplatform == b'plan9':
# vi is the MIPS instruction simulator on Plan 9. We # vi is the MIPS instruction simulator on Plan 9. We
# instead default to E to plumb commit messages to # instead default to E to plumb commit messages to
# avoid confusion. # avoid confusion.
editor = b'E' editor = b'E'
elif pycompat.isdarwin:
# vi on darwin is POSIX compatible to a fault, and that includes
# exiting non-zero if you make any mistake when running an ex
# command. Proof: `vi -c ':unknown' -c ':qa'; echo $?` produces 1,
# while s/vi/vim/ doesn't.
editor = b'vim'
else: else:
editor = b'vi' editor = b'vi'
return encoding.environ.get(b"HGEDITOR") or self.config( return encoding.environ.get(b"HGEDITOR") or self.config(
b"ui", b"editor", editor b"ui", b"editor", editor
) )
@util.propertycache @util.propertycache
def _progbar(self): def _progbar(self):