do not leave Getopt::Long reconfigured

That is: set back to previous config after being called.

Changes

@@ -1,6 +1,8 @@
 Revision history for Getopt-Long-Descriptive
 
 {{$NEXT}}
+        - do not leave Getopt::Long configuration in an altered state after
+          getting options
 
 0.115     2024-11-07 18:00:02+00:00 Europe/Dublin
         - cope with the user forgetting the first argument, generally "%c %o",

lib/Getopt/Long/Descriptive.pm

@@ -474,12 +474,14 @@ sub _build_describe_options {
       show_defaults => $arg->{show_defaults},
     });
 
-    Getopt::Long::Configure(@go_conf);
+    my $old_go_conf = Getopt::Long::Configure(@go_conf);
 
     my %return;
     $usage->die unless GetOptions(\%return, grep { length } @getopt_specs);
     my @given_keys = keys %return;
 
+    Getopt::Long::Configure($old_go_conf);
+
     for my $opt (keys %return) {
       my $newopt = _munge($opt);
       next if $newopt eq $opt;

t/descriptive.t

@@ -494,4 +494,23 @@ subtest "descriptions for option value types" => sub {
   is ($p->('=f%'), ' KEY=NUM...', 'float maps');
 };
 
+{
+  # Asking Getopt::Long::Descriptive to use a specific Getopt::Long config
+  # should not alter the global state after the describe_options(...) call has
+  # returned!
+  ok(!$Getopt::Long::gnu_compat, "Getopt::Long::gnu_compat starts life false");
+
+  is_opt(
+    [ ],
+    [
+      [ "foo-bar=i", "foo integer", { default => 17 } ],
+      { getopt_conf => [ 'gnu_compat' ] },
+    ],
+    { foo_bar => 17 },
+    "default foo_bar with no short option name",
+  );
+
+  ok(!$Getopt::Long::gnu_compat, "Getopt::Long::gnu_compat still false after getopt");
+}
+
 done_testing;