[pdftex] Regression: Wrong spacing with explicit space character of different font

[Heiko Oberdiek]

Hello,

the following TeX file for iniTeX causes a weird space between "@" and
"s", although the width of the box in between is explicitly set to zero.
This happens with PDF mode of pdfTeX, version:

    3.14159265-2.6-1.40.15 (TeX Live 2014)

DVI mode works fine, as older versions:

    3.1415926-2.5-1.40.14 (TeX Live 2013)
    3.1415926-2.4-1.40.13 (TeX Live 2012)
    3.1415926-1.40.10-2.2 (TeX Live 2009)

(Also LuaTeX or XeTeX are not affected.)

Test file for reproducing:

% test.tex
\catcode`\{=1
\catcode`\}=2
\showboxdepth=1000
\showboxbreadth=1000
\tracingonline=1

\font\ph=phvr8r
\font\rm=cmr10
\setbox0=\hbox{%
  \rm a@\hbox to 0pt{\ph\char32\hss}srv.com%
}
\scrollmode\showbox0
\shipout\copy0
\csname @@end\endcsname\end

Run with:

    pdftex -ini -output-format=pdf test

The result of \showbox is fine:

    .\rm @
    .\hbox(0.0+0.0)x0.0, glue set - 2.77989fil
    ..\ph
    ..\glue 0.0 plus 1.0fil minus 1.0fil
    .\rm s

But the PDF code is not (reformatted):

    BT
      /F2 9.9626 Tf
      72 72 Td
      [(a@)] TJ
      /F1 9.9626 Tf
      12.73 0 Td
      [(\040)] TJ
      /F2 9.9626 Tf
      [(srv.com)] TJ
    ET

Older versions of pdfTeX generates instead (reformatted):

    BT
      /F2 9.9626 Tf
      72 72 Td
      [(a@)] TJ
      /F1 9.9626 Tf
      12.73 0 Td
      [(\040)] TJ
      /F2 9.9626 Tf
      0 0 Td
      [(srv.com)] TJ
    ET

Thus "0 0 Td" is missing in the current pdfTeX version.

The problem is quite serious, already a simple document such as

    \documentclass{article}
    \begin{document}
    \noindent
    \rlap{\textbf{Hello}}World
    \end{document}

fails, "Hello" does not overlap "World".

Yours sincerely
  Heiko Oberdiek

PS:
http://www.tug.org/applications/pdftex/
is quite out of date. Also the bug report
address at sarovar does not seem to work
anymore.