Can't always use redo after save

[michael-ud]

Summary

In certain circumstances, saving a buffer incorrectly prevents redo after save.

1. In terminal

mkdir /tmp/issue31917
cd $_
echo 'foo' > foo.txt
zed . foo.txt:1:1

2. enter, cms-s, cmd-z, cmd-s, cmd-shift-z

Expected Behavior: Redo (cmd-shift-z) should restore the newline

Actual Behavior: Redo action does nothing

In other circumstances the redo buffer is correctly preserved (as expected). See comment below for one such case where Zed handles it correctly.

For cases when the buffer changes during format_on_save, see this feature request:

• Support redo after autoformat changes buffer #31984

Settings

Reproducible with empty settings {}
No formatter.

Zed Version and System Specs

Zed: v0.188.5 (Zed)
OS: macOS 15.5.0
Memory: 16 GiB
Architecture: aarch64

[notpeter]

I've added a feature request for this.
Please 👍 upvote and subscribe to track progress.

• Support redo after autoformat changes buffer #31984

[orokusaki]

@notpeter in this particular case, the buffer was not changed by a formatter. This is a bug / regression. This same thing has already worked. I don't think it's necessary to support redo after a formatter has made changes (that could be a mess, especially if it's a formatter like Ruff, which is making major changes). I'm simply saying that, if no changes were made to the buffer, by the formatter, upon saving, then redo should work, as it did only a week before.

[notpeter]

Can you provide super-explicit character by character instructions to reproduce?
This works for me in Zed Nightly 0.191.0:

My steps

1. open a new file
2. save it as something (foo, bar.txt, whatever).
3. type the following three lines: foo <enter> bar <enter> baz <enter>
4. save (foo bar baz)
5. replace bar with buzz
6. save (foo buzz baz)
7. undo
8. save (foo bar baz)
9. redo (foo buzz baz)

I can trigger the behavior you are describing if there ANY whitespace changes based on formatting, notably if I type foo bar <undo> I'm left with foo , which becomes foo on save and blow away the redo buffer.

Happy to reopen if you have steps which allows me to repro.

[orokusaki]

Hey @notpeter, thanks for the reply. Here's a slightly different example I used to reproduce the problem:

1. Ensure relevant settings match mine (in comment above from my work profile)
2. Paste the contents (below) into a new buffer
3. Save the buffer as example.py
4. Place cursor above function definition and hit return to add a newline
5. Save the file again
6. Undo the newline via CMD + Z
7. Save the file again
8. Then, attempt to redo the newline, via CMD + SHIFT + Z

Contents

def spam():
    return 'eggs'

This seems like a strange workflow, but it's common to redo such undone changes, even after resaving the original, e.g., just to copy something from the redo version to bring back and paste in the undo version.

[notpeter]

I can reproduce with empty settings in a plain text buffer using your steps so I've edited the original description and reopened. Thanks for following up.

extra settings feedback

Re: settings:

1. you have format_on_safe instead of format_on_save in your settings.
2. Use languages instead of language_overrides which has been deprecated for a year:

• Settings Deprecation Notice 2024-06-17: language_overrides, show_copilot_suggestions and features.copilot #13171

[michael-ud]

Thanks @notpeter, and thanks (re: settings)

[notpeter]

I did the bisect, it broke in 53cde32

• Clean up formatting code and add testing for formatting with multiple formatters (including code actions!) #28457

CC: @probably-neb