* fix #39907: only load system class types from units that are marked as a System unit

+ added test

compiler/symdef.pas

@@ -7772,6 +7772,12 @@ implementation
          { handles the predefined class tobject  }
          { the last TOBJECT which is loaded gets }
          { it !                                  }
+         { but do this only from a unit that's   }
+         { marked as system unit to avoid some   }
+         { equally named user's type to override }
+         { the internal types!                   }
+         if mf_system_unit in current_module.moduleflags then
+           begin
              if (childof=nil) and
                 (objecttype in [odt_class,odt_javaclass]) and
                 (objname^='TOBJECT') then
@@ -7811,6 +7817,8 @@ implementation
                  else if (objname^='FPCBASEPROCVARTYPE') then
                    java_procvarbase:=self;
                end;
+           end;
+
          writing_class_record_dbginfo:=false;
        end;
 

tests/webtbs/tw39907.pp

@@ -0,0 +1,18 @@
+{ %NORUN }
+{ %RECOMPILE }
+
+{$mode objfpc}
+{$modeswitch functionreferences}
+
+program tw39907;
+uses
+  uw39907;
+
+var
+  obj: TObject;
+  proc: reference to procedure;
+begin
+  obj := TObject.Create;
+  proc := @obj.Free;
+end.
+

tests/webtbs/uw39907.pp

@@ -0,0 +1,13 @@
+{$mode objfpc}
+
+unit uw39907;
+interface
+
+type
+  TObject = class
+  end;
+
+implementation
+
+end.
+