Basic enabling of Ruby 3

src/klayout.pri

@@ -154,6 +154,9 @@ msvc {
   # because we use unordered_map/unordered_set:
   QMAKE_CXXFLAGS += -std=c++0x
 
+  # needed for Ruby 3.0
+  QMAKE_CXXFLAGS += -fdeclspec
+
   win32 {
     QMAKE_LFLAGS += -Wl,--exclude-all-symbols
   } else {

src/rba/rba/rbaConvert.cc

@@ -224,7 +224,7 @@ object_to_ruby (void *obj, Proxy *self, const gsi::ClassBase *cls, bool pass_obj
     //  a Ruby object. If it already has, we simply return a reference to this.
     ret = rba_data->self ();
 
-#if HAVE_RUBY_VERSION_CODE >= 20200
+#if HAVE_RUBY_VERSION_CODE >= 20200 && HAVE_RUBY_VERSION_CODE < 30000
     //  Mark the returned object - the original one may have been already
     //  scheduled for sweeping. This happens at least for Ruby 2.3 which
     //  has a two-phase GC (mark and sweep in separate steps). If by chance

testdata/ruby/basic_testcore.rb

@@ -894,8 +894,10 @@ class Basic_TestClass < TestBase
 
   end
 
-  # TODO: this class is going to be deprecated
-  class X < Data
+  if RUBY_VERSION < "3.0.0"
+    # TODO: this class is going to be deprecated
+    class X < Data
+    end
   end
   class Y < Object
   end
@@ -907,12 +909,14 @@ class Basic_TestClass < TestBase
     end
 
     # Test, if this throws an error (object of class X passed to A argument):
-    begin
-      b = RBA::B.new
-      assert_equal( b.b4( X.new ), "b4_result: -6" )
-      assert_equal( false, true )  # this must never hit
-    rescue
-      assert_equal( $!.to_s(), "allocator undefined for Basic_TestClass::X" );
+    if RUBY_VERSION < "3.0.0"
+      begin
+        b = RBA::B.new
+        assert_equal( b.b4( X.new ), "b4_result: -6" )
+        assert_equal( false, true )  # this must never hit
+      rescue
+        assert_equal( $!.to_s(), "allocator undefined for Basic_TestClass::X" );
+      end
     end
   
     # Test, if this throws an error (object of class X passed to A argument):