Outdated `prettier` and recent formatter change results in unwanted blank line removal before last comment

[antonc42]

Describe the bug

In the recent 1.20.0 version, the #1179 PR came into effect, which enabled formatting for Ansible YAML files.

When the formatting is applied, the blank line before the last comment in my Ansible YAML files is removed. See the expected/current behavior.

I may be incorrect, but I believe this is due to using an old version of prettier. I found the following issue in prettier that seems to describe this behavior: prettier/prettier#10922. The issue was fixed in prettier/prettier#17843 (commit: prettier/prettier@94b9a05). This was apparently first included in the 3.7.0 release.

From what I can tell, this extension has pinned prettier at version 2.2.1, which is now over five years old.

Can the prettier version be updated to fix this issue?

Expected Behavior

The formatter makes no change to this file.

some_var: Some Value


# comment
other_var: Other Value

Current Behavior

The formatter removes the blank line(s) before the last comment.

some_var: Some Value
# comment
other_var: Other Value

Steps to Reproduce

1. Install extension 1.20.0.
2. Enable yaml.format.enable setting (the default) and optionally the editor.formatOnSave in VSCode.
3. Save the file, or manually perform formatting on the Ansible YAML file.
4. Observe the undesired removal of blank lines before the last comment.

Environment

I only tested on Linux, not on other platforms, so I don't know if it is an issue there, but I suspect it will be.

• Windows
• Mac
• Linux
• other (please specify)

[datho7561]

Hello! In 1.21.0, which was releasing right when you were submitting this, we updated the included prettier from 3.5.0 to 3.8.1: redhat-developer/yaml-language-server@425f02a. I tried it out, and the behaviour is different from both the previous behaviour and your desired behaviour:

Before:

some_var: Some Value


# comment
other_var: Other Value

After:

some_var: Some Value

# comment
other_var: Other Value

Is this behaviour okay?

[antonc42]

The behavior where is collapses multiple blank lines to one is okay. As long as there is at least one.

I'm having some strange inconsistent behavior when testing. My example behavior now works correctly, but there are still some cases where it incorrectly removes the blank line. There might still be an upstream bug. I'll have to investigate further.

Formatting file with this content:

---
var2: |
  val
a: b

# other vars
c: d

Results in the incorrect removal of the blank line:

---
var2: |
  val
a: b
# other vars
c: d

I think it has something to do with the | folding operator.

We can close this issue.

Thanks for the help and all your hard work!