#2368 gnuplot 5.4 patchlevel 0 under cygwin does not recognize value qualified columns (such as $1) in a "plot using ..." command

[Anonymous]

The attached gnuplot code runs correctly under gnuplot 5.2 patchlevel 8 and produces a plot (GnuplotBug.png) ut fails in gnuplot 5.4 patchlevel 0.

show version
set terminal pngcairo 
OutputPlot = sprintf("GnuplotBug.png")
set output OutputPlot
set title sprintf("gnuplot % 4.1f patchlevel %s ",GPVAL_VERSION,GPVAL_PATCHLEVEL)
plot ARG1 using ($1):2

When run from a command shell terminal window thus:

gnuplot -c plot.gp data.txt

at line 12 in the attached plot.gp gnuplot script:

Version 5.2 sees the value $1 and the script produces attached GnuplotBug.png output correctly.

Version 5.4 does not see value $1 and the script fails. thus:

        G N U P L O T
        Version 5.4 patchlevel 0    last modified 2020-07-13

        Copyright (C) 1986-1993, 1998, 2004, 2007-2020
        Thomas Williams, Colin Kelley and many others

        gnuplot home:     http://www.gnuplot.info
        faq, bugs, etc:   type "help FAQ"
        immediate help:   type "help"  (plot window: hit 'h')


**plot ARG1 using ():2
                 ^
"plot.gp" line 6: invalid expression**

[Ethan Merritt]

Thank you for the bug report and the excellent reproducer.
This failure in 5.4.0 has the same cause as reported in https://sourceforge.net/p/gnuplot/bugs/2298/
although this manifestation is more serious because I can't think of an easy work-around.

The fix will be in 5.4.1, to be released soon (next month?)

[Leonard]

I see. (I submitted the bug report.) I found that replacing $1 with $$1 causes the script to function correctly with gnuplot 5.4.0. I hope that future releases are subject to some set of standard regression tests.