Should Insert Final Newline be on by default?

[DavisVaughan]

RStudio has this on by default and I think it is very helpful. i.e. I was just editing a _pkgdown.yml file and forgot the final new line and saw this when running pkgdown::build_site():

Warning message:
In readLines(con, warn = readLines.warn) :
  incomplete final line found on './_pkgdown.yml'

---

There is also this secondary option, which I think I like and will opt into, but I don't think we need to turn it on by default

[petetronic]

While we may want this behavior for our team, it does seem like a decision customer teams will need to make themselves... and probably best left to the existing default from vscode.

[DavisVaughan]

I am realizing that I actually asked for this already (ill close that one)
#726

Interesting that we use this in Positron and amalthea

positron/.vscode/settings.json

Line 95 in f28cfcd

"files.insertFinalNewline": true,

I do wonder if this has the possibility to pop up for a lot of R developers, since readLines() (a common way to read a file in R) seems like it is going to consistently throw a warning on this.

GitHub will also tell you that a final newline is missing with a red symbol, so I think this is a common convention

I also think git will complain

Lots of good reasons for it here too https://stackoverflow.com/questions/5813311/whats-the-significance-of-the-no-newline-at-end-of-file-log

It is also apparently a POSIX standard to end a file with a new line
microsoft/vscode#141169

[lionel-]

Personally I'm all for changing VS Code defaults for this sort of settings that help developer communities converge towards shared conventions, especially when the convention is so well established.

It looks like pylint also warns about final newlines missing: http://pylint-messages.wikidot.com/messages:c0304

[nealrichardson]

Maybe this isn't the right way to think about it, but I expect adding a trailing newline to be part of the "format on save" action, that is, not a separate VSCode setting but something controlled by a language module or formatter that is triggered by format-on-save. In VSCode, if you have format-on-save enabled, black will insert a trailing newline in python files, styler will add it in R files, clang-format will for C/C++, and so on. This is all without "Insert Final Newline" enabled.

So if anything, I'd wonder if the right question is if format-on-save should be on by default (I'd advocate for it), and making sure we include the right formatters for Python and R and any other languages we want great out-of-the-box support for.

[kevinushey]

The POSIX standard requires source files to end with a newline. We wouldn't want to encourage users to violate the POSIX standard, would we? 😉

Also, fun fact: if your ~/.Rprofile doesn't have a trailing newline, then the last line / statement will be silently ignored. I think we should protect users from these sorts of insidious issues.