#2442 continuation character "\" at end of comment lines not handled correctly

[internationils]

Gnuplot does not handle "\" continuation character at end of comment lines correctly.
Tested on Ubuntu 20.10 with gnuplot 5.2 patchlevel 8

replot
^
"demo2.plot" line 8: no previous plot

...simple example below. Remove the trailing "\" in the comment line to make it work.

a = 0.9
f(x) = a * sin(x)
g(x) = a * cos(x)

#plot f(x) title 'sin(x)' with lines linestyle 1, \
plot f(x) title 'sin(x)' with lines linestyle 1, \
     g(x) notitle with lines linestyle 2
replot
pause -1

[Hans-Bernhard Broeker]

Your expectation of what "correct behaviour" would be in this case is unjustified.

[internationils]

https://pubs.opengroup.org/onlinepubs/009695399/utilities/xcu_chap02.html#tag_02_03
...see rule 10, that was essentially my expectation - "If the current character is a '#', it and all subsequent characters up to, but excluding, the next <newline> shall be discarded as a comment. The <newline> that ends the line is not considered part of the comment."
I had assumed this functionality since you are using shell-style comments. Else please point me to something that would justify the "correct behaviour" so I can understand where I went wrong and don't make wrong assumptions. Thanks!

[Ethan Merritt]

Here is the section from gnuplot documentation:

gnuplot> help comments

 The comment character `#` may appear almost anywhere in a command line, and
 `gnuplot` will ignore the rest of that line. A `#` does not have this effect
 inside a quoted string. Note that if a commented line ends in '\' then the
 subsequent line is also treated as part of the comment.