R devel - Feb 2023 - R2HTML doesn't split paragraphs originating from \Sexpr[results=rd]

Hello,

Here's an example that renders correctly using Rd2txt / Rd2latex / R
CMD Rd2pdf, but has problems under Rd2HTML:

\name{foo}
\title{foo}
\section{foo}{
  This should be on a separate paragraph

  This should be on a separate paragraph

  This should be on a separate paragraph

  \Sexpr[stage=render,results=rd]{
    paste(
      rep('Sexpr: This should be on a separate paragraph', 3),
      collapse = '\n\n'
    )
  }
}

For the text I've typed manually, there are <p>...</p> tags
splitting
the text separated by empty lines into paragraphs. The \Sexpr return
value only has newlines, which joints the paragraphs together:

<p>This should be on a separate paragraph
</p>
<p>This should be on a separate paragraph
</p>
<p>This should be on a separate paragraph
</p>
<p>Sexpr: This should be on a separate paragraph

Sexpr: This should be on a separate paragraph

Sexpr: This should be on a separate paragraph
</p>

addParaBreaks() is prevented from closing the paragraph tag because
tools:::isBlankLineRd() returns FALSE for blank lines produced by a
\Sexpr. This happens because utils:::getSrcByte() not 1 for these blank
lines. That, in turn, is because the source reference for \Sexpr values
is the whole \Sexpr tag:

# blank line from a \Sexpr
Rd[[3]][[2]][[9]][[2]]
# [1] "\n"
# attr(,"Rd_tag")
# [1] "TEXT"
getSrcref(Rd[[3]][[2]][[9]][[2]])
# \Sexpr[stage=render,results=rd]{
#   paste(
#     rep('Sexpr: This should be on a separate paragraph', 3),
#     collapse = '\n\n'
#   )
# }

# artisanal hand-crafted blank line
Rd[[3]][[2]][[7]]
# [1] "\n"
# attr(,"Rd_tag")
# [1] "TEXT"
summary(getSrcref(Rd[[3]][[2]][[7]]))
# <srcref: file "~/foo.Rd" chars 9:1 to 9:1>

I think I understand that tools:::isBlankLineRd requires
utils:::getSrcByte(x) == 1L because it may be called on things like
"\\eqn{0}\n" where the terminal "\n" might otherwise be
considered a
"blank line". How to reconcile isBlankLineRd with blank lines not
directly originating from Rd source?

Rd2latex might have a similar problem (its addParaBreaks() checks for
isBlankLineRd()), but then it works anyway because Rd rules for
paragraph breaks on blank lines are the same as in LaTeX.

-- 
Best regards,
Ivan

I can confirm this is a bug, more specifically, a regression in R >= 
3.6.0. I think a report in R's Bugzilla would be useful.

A possible workaround seems to be to start the Rd-generating \Sexpr in 
column 1 of the Rd file, so to remove the indentation before \Sexpr.

AFAICS, fixing this will require tools:::processRdChunk() to keep two 
types of source references for dynamically generated Rd code: the 
effective "srcref" from parsing the Rd fragment, and the one that
refers
to the source Sexpr block (possibly called "wholeSrcref"), to be used
by
checkRd() in preference to "srcref" when reporting the location of Rd 
problems.

	Sebastian Meyer


Am 05.02.23 um 14:04 schrieb Ivan Krylov:
> Hello,
> 
> Here's an example that renders correctly using Rd2txt / Rd2latex / R
> CMD Rd2pdf, but has problems under Rd2HTML:
> 
> \name{foo}
> \title{foo}
> \section{foo}{
>    This should be on a separate paragraph
> 
>    This should be on a separate paragraph
> 
>    This should be on a separate paragraph
> 
>    \Sexpr[stage=render,results=rd]{
>      paste(
>        rep('Sexpr: This should be on a separate paragraph', 3),
>        collapse = '\n\n'
>      )
>    }
> }
> 
> For the text I've typed manually, there are <p>...</p> tags
splitting
> the text separated by empty lines into paragraphs. The \Sexpr return
> value only has newlines, which joints the paragraphs together:
> 
> <p>This should be on a separate paragraph
> </p>
> <p>This should be on a separate paragraph
> </p>
> <p>This should be on a separate paragraph
> </p>
> <p>Sexpr: This should be on a separate paragraph
> 
> Sexpr: This should be on a separate paragraph
> 
> Sexpr: This should be on a separate paragraph
> </p>
> 
> addParaBreaks() is prevented from closing the paragraph tag because
> tools:::isBlankLineRd() returns FALSE for blank lines produced by a
> \Sexpr. This happens because utils:::getSrcByte() not 1 for these blank
> lines. That, in turn, is because the source reference for \Sexpr values
> is the whole \Sexpr tag:
> 
> # blank line from a \Sexpr
> Rd[[3]][[2]][[9]][[2]]
> # [1] "\n"
> # attr(,"Rd_tag")
> # [1] "TEXT"
> getSrcref(Rd[[3]][[2]][[9]][[2]])
> # \Sexpr[stage=render,results=rd]{
> #   paste(
> #     rep('Sexpr: This should be on a separate paragraph', 3),
> #     collapse = '\n\n'
> #   )
> # }
> 
> # artisanal hand-crafted blank line
> Rd[[3]][[2]][[7]]
> # [1] "\n"
> # attr(,"Rd_tag")
> # [1] "TEXT"
> summary(getSrcref(Rd[[3]][[2]][[7]]))
> # <srcref: file "~/foo.Rd" chars 9:1 to 9:1>
> 
> I think I understand that tools:::isBlankLineRd requires
> utils:::getSrcByte(x) == 1L because it may be called on things like
> "\\eqn{0}\n" where the terminal "\n" might otherwise be
considered a
> "blank line". How to reconcile isBlankLineRd with blank lines not
> directly originating from Rd source?
> 
> Rd2latex might have a similar problem (its addParaBreaks() checks for
> isBlankLineRd()), but then it works anyway because Rd rules for
> paragraph breaks on blank lines are the same as in LaTeX.
>