[luatex] Spaces in the log: \scrollmode or not, LuaTeX or pdfTeX

[Hans Hagen]

On 8/20/2016 3:43 PM, Joseph Wright wrote:
> Hello all,
>
> With example
>
>     \scrollmode
>
>     \ifx\zzz\undefined\else\expandafter\endinput\fi
>
>     \def\zzz{}
>
>     \input \jobname
>
>     \end
>
> we get with pdfTeX
>
>     This is pdfTeX, Version 3.14159265-2.6-1.40.17 (TeX Live 2016)
> (preloaded format=pdftex)
>      restricted \write18 enabled.
>     entering extended mode
>     (./test.tex
>     (./test.tex
>     ) )
>
> but with \scrollmode commented get
>
>     This is pdfTeX, Version 3.14159265-2.6-1.40.17 (TeX Live 2016)
> (preloaded format=pdftex)
>      restricted \write18 enabled.
>     entering extended mode
>     (./test.tex (./test.tex) )
>     No pages of output.
>     Transcript written on test.log.
>
> (and similar for other engines) whilst LuaTeX gives respectively
>
>     This is LuaTeX, Version 0.95.0 (TeX Live 2016)
>      restricted system commands enabled.
>     (./test.tex
>     (./test.tex
>     ))
>     warning  (pdf backend): no pages of output.
>     Transcript written on test.log.
>
> and
>
>     This is LuaTeX, Version 0.95.0 (TeX Live 2016)
>      restricted system commands enabled.
>     (./test.tex (./test.tex))
>     warning  (pdf backend): no pages of output.
>     Transcript written on test.log.
>
> Is there some logic to the variation here?

Warnings are not suppressed with scrollmode (I wonder why pdftex does 
suppress them unless in batchmode).

Concerning spaces: we're not (even aiming at exact) log compatible. 
Warnings, errors etc are kind of normalized and can get intercepted with 
lua. Things like opening / closing files - the () thing - as well as the 
way names get repported can differe with e.g. pdftex (maybe even more in 
the future).

The way tex reports (macros, expansion stuff, boxes etc) we try to keep 
as compatible as possible / reasonable.

Backend and engine messages are often independent things anyway.

Hans
Hans

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