handle Gnuplot 6 warnings about Qt plugins

CHANGES

@@ -1,3 +1,5 @@
+- handle Gnuplot 6 warnings about Qt plugins
+
 2.027 2024-07-31
 - add "resample" curve option for with=>'fits'
 - with=>'fits' error if no FITS header

lib/PDL/Graphics/Gnuplot.pm

@@ -7470,6 +7470,7 @@ sub _printGnuplotPipe
 # are explicitly stripped out
 our $cp_serial = 0;
 
+my $qt_re = qr/^qt.qpa.plugin: Could not find the Qt platform plugin.*/m;
 sub _checkpoint {
     my $this   = shift;
     my $suffix = shift || "main";
@@ -7602,16 +7603,18 @@ EOM
     # that some warnings come with a line specifier and others don't.
 
   WARN: while( $fromerr =~ m/^(\s*(line \d+\:\s*)?[wW]arning\:.*)$/m or
+	       $fromerr =~ m/$qt_re/ or
 	       $fromerr =~ m/^Populating font family aliases took/m     # CED - Quicktime on MacOS Catalina throws a warning marked as an error.  Stupid.
 	) {
-      if($2){
+      if ($2) {
 	  # it's a warning with a line specifier. Break off two more lines before it.
 	  last WARN unless($fromerr =~ s/^((gnu|multi)plot\>.*\n\s*\^\s*\n\s*(line \d+\:\s*)?[wW]arning\:.*(\n|$))//m);
 	  my $a = $1;
 	  $a =~ s/^\s*line \d+\:/Gnuplot:/m;
 	  carp $a if($printwarnings);
       } else {
-	  last WARN unless($fromerr =~ s/^(\s*(line \d+\:\s*)?[wW](arning\:.*(\n|$)))//m);
+	  $fromerr =~ s/$qt_re//;
+	  last WARN unless $fromerr =~ s/^(\s*(line \d+\:\s*)?[wW](arning\:.*(\n|$)))//m;
 	  carp "Gnuplot w$3\n" if($printwarnings);
       }
 

t/plot.t

@@ -549,9 +549,11 @@ SKIP: {
 	skip "Skipping interactive tests - set env. variable GNUPLOT_INTERACTIVE to enable.",29;
     }
 
-    eval { $w = gpwin('wxt') };
-    eval { $w = gpwin('x11') } if $@;
-    is($@, '', "created a wxt or x11 plot object");
+    for (qw(qt wxt x11)) {
+      eval { $w = gpwin($_) };
+      last if !$@;
+    }
+    is($@, '', "created a plot object");
 
     isa_ok $PDL::Graphics::Gnuplot::termTab->{$w->{terminal}}, 'HASH', "Terminal is a known type";