`scribble/text-render` doesn't respect `(linebreak)`

[LiberalArtist]

Scribble doesn't handle (linebreak) properly when generating plain text output. For example:

philip@bastet:/tmp/scrbl$ cat scribble-text-newline.scrbl 
#lang scribble/base

abc @(linebreak) 123
philip@bastet:/tmp/scrbl$ scribble --text scribble-text-newline.scrbl 

 [Output to scribble-text-newline.txt]
philip@bastet:/tmp/scrbl$ cat scribble-text-newline.txt 
abc  123
philip@bastet:/tmp/scrbl$

It looks like something needs to happen in render-paragraph, but I'm not immediately sure how to communicate which newlines to keep—maybe specials?

Related to https://github.com/racket/racket/pull/4301

Edit: Fixed the example.

[sorawee]

I'm a bit confused. I think you want the evaluation result to be something that has newline characters, not printing a newline character (which is what newline does), no?

#lang scribble/base

abc @(newline) 123
@(displayln "qwerty")

I don't expect to see any qwerty in the generated file either (but I do get the newline and qwerty in the stdout).

According to the doc of decode-flow:

A sequence of two or more newlines separated only by whitespace is parsed as a compound-paragraph separator.

So:

#lang scribble/base

abc
def

is rendered as:

abc def

while:

#lang scribble/base

abc

def

is rendered as:

abc

def

So if you want a new paragraph, perhaps use '("\n" "\n") or something like that?

#lang scribble/base

abc@|'("\n" "\n")|def

for me correctly outputs:

abc

def

[LiberalArtist]

Ah, sorry, I wrote this confusingly. I meant (linebreak) from scribble/base, which produces an element with the style name 'newline. I'll edit the post above. The implementation in https://github.com/racket/scribble/pull/334 works (with caveats as noted); I'll fix the commit message now.

[sorawee]

Ah, yes, I think it is indeed broken.

@history from scribble/manual is at least one place that uses linebreak, and it is rendered incorrectly in the text mode too.