Missing character warnings when dividing large numbers by 1e9

[frx-wintermute]

Hello and thanks for developing pgfplots!

I am seeing missing character warnings in some plots. Please take a look at the following MWE:

\documentclass[tikz,margin=1pt]{standalone}
\usepackage{pgfplots}
\pgfplotsset{compat=1.18}
\begin{document}
\begin{tikzpicture}
  \pagecolor{white}
  \begin{axis}
    \addplot
    table
    [
      x expr={\thisrowno{0}/1e9},
      y expr={\thisrowno{1}},
    ]
    {
      1100000000   30
      1400000000   80
      1800000000   65
    };
  \end{axis}
\end{tikzpicture}
\end{document}

The PDF file obtained (with both pdflatex and lualatex) looks correct, but I see the following warnings:

$ texfot pdflatex null_ch_test
/usr/bin/texfot: invoking: pdflatex null_ch_test
This is pdfTeX, Version 3.141592653-2.6-1.40.28 (TeX Live 2025/Debian) (preloaded format=pdflatex)
Missing character: There is no 0 in font nullfont!
Missing character: There is no 0 in font nullfont!
Missing character: There is no 0 in font nullfont!
Missing character: There is no 0 in font nullfont!
Missing character: There is no 0 in font nullfont!
Missing character: There is no 0 in font nullfont!
Missing character: There is no 0 in font nullfont!
Missing character: There is no 0 in font nullfont!
Output written on null_ch_test.pdf (1 page, 19452 bytes).
$ texfot lualatex null_ch_test
/usr/bin/texfot: invoking: lualatex null_ch_test
This is LuaHBTeX, Version 1.22.0 (TeX Live 2025/Debian) 
Missing character: There is no 0 (U+0030) in font nullfont!
Missing character: There is no 0 (U+0030) in font nullfont!
Missing character: There is no 0 (U+0030) in font nullfont!
Missing character: There is no 0 (U+0030) in font nullfont!
Missing character: There is no 0 (U+0030) in font nullfont!
Missing character: There is no 0 (U+0030) in font nullfont!
Missing character: There is no 0 (U+0030) in font nullfont!
Missing character: There is no 0 (U+0030) in font nullfont!
Output written on null_ch_test.pdf (1 page, 17865 bytes).

Please note that an identical PDF file may be obtained without any warnings with the following modified LaTeX code:

\documentclass[tikz,margin=1pt]{standalone}
\usepackage{pgfplots}
\pgfplotsset{compat=1.18}
\begin{document}
\begin{tikzpicture}
  \pagecolor{white}
  \begin{axis}
    \addplot
    table
    [
      x expr={\thisrowno{0}},
      y expr={\thisrowno{1}},
    ]
    {
      1.100000000   30
      1.400000000   80
      1.800000000   65
    };
  \end{axis}
\end{tikzpicture}
\end{document}

Is there anything wrong with the MWE code?
Or is there anything that should be fixed in pgfplots?

Please let me know, thanks for your time and dedication! :-)

[hmenke]

Possible patch. What do you think @muzimuzhi?

diff --git a/tex/generic/pgfplots/numtable/pgfplotstableshared.code.tex b/tex/generic/pgfplots/numtable/pgfplotstableshared.code.tex
index e1d934d3..31b5b889 100644
--- a/tex/generic/pgfplots/numtable/pgfplotstableshared.code.tex
+++ b/tex/generic/pgfplots/numtable/pgfplotstableshared.code.tex
@@ -1849,7 +1849,8 @@
 	\ifpgfplotstable@search@header
 		\ifpgfplotstableread@curline@contains@colnames
 		\else
-			\pgfplotstableread@if@finite{#1}{%
+			\edef\pgfplotstable@loc@TMPa{#1}%
+			\pgfplotstableread@if@finite\pgfplotstable@loc@TMPa{%
 				\pgfplotstableread@isnumber@ITERATE#1\pgfplotstable@EOI%
 			}{}%
 %\ifpgfplotstableread@curline@contains@colnames\pgfplots@message{'#1' is a column name!}\else\pgfplots@message{'#1' is NO column name!}\fi

If you want to backport this patch to your document, add this to the preamble after loading pgfplots (and pgfplotstable)

\makeatletter
\long\def\pgfplotstableread@impl@countcols@and@identifynames@NEXT#1{%
  \pgfplotstableread@countadvance\pgfplotstableread@curcol
  \ifpgfplotstable@search@header
    \ifpgfplotstableread@curline@contains@colnames
    \else
      \edef\pgfplotstable@loc@TMPa{#1}%
      \pgfplotstableread@if@finite\pgfplotstable@loc@TMPa{%
        \pgfplotstableread@isnumber@ITERATE#1\pgfplotstable@EOI%
      }{}%
    \fi
  \fi
}
\makeatother

[frx-wintermute]

[...]

If you want to backport this patch to your document, add this to the preamble after loading pgfplots (and pgfplotstable)

\makeatletter
\long\def\pgfplotstableread@impl@countcols@and@identifynames@NEXT#1{%
  \pgfplotstableread@countadvance\pgfplotstableread@curcol
  \ifpgfplotstable@search@header
    \ifpgfplotstableread@curline@contains@colnames
    \else
      \edef\pgfplotstable@loc@TMPa{#1}%
      \pgfplotstableread@if@finite\pgfplotstable@loc@TMPa{%
        \pgfplotstableread@isnumber@ITERATE#1\pgfplotstable@EOI%
      }{}%
    \fi
  \fi
}
\makeatother

I tried this in-document patch and I can confirm that it makes the warnings go away, while preserving an identical PDF output.
Thanks for devising a patch!