"make check" fails for gnuplot-6.0.1 on Gentoo Linux in file demo/watchpoints.dem:
*********************** file watchpoints.dem *********************
Plot title: plot FOO smooth cnormal
watch y=.25 watch y=.50 watch y=.75
Watch 1 target y = 0.25 (1 hits)
hit 1 x 50.6 y 0.25
Watch 2 target y = 0.5 (1 hits)
hit 1 x 63.6 y 0.5
Watch 3 target y = 0.75 (1 hits)
hit 1 x 68.3 y 0.75
<cr> to continue<cr> to continue
Variables beginning with INTERSECT:
INTERSECT_X = 167.511137525825
INTERSECT_Y = 20.2444312370877
<cr> to continue"watchpoints.dem" line 81: undefined function: FresnelC
make[3]: *** [Makefile:744: check-noninteractive] Error 1
make[2]: *** [Makefile:599: check-am] Error 2
make[1]: *** [Makefile:449: check-recursive] Error 1
make: *** [Makefile:432: check-recursive] Error 1
The problem is that function FresnelC only exists when gnuplot was configured to link against libcerf.
Attached patch fixes the problem for me.
Applied, thanks. Although only the final plot needs to be skipped; the preceding plots do not depend on any special functions.