Fix for Mantis #24903.

ncon.pas, tstringconstnode:
  * buildderefimpl: don't build the deref if we don't need to
  * derefimpl: do not try to resolve the deref if it wasn't stored at all

git-svn-id: trunk@25329 -

compiler/ncon.pas

@@ -912,14 +912,16 @@ implementation
     procedure tstringconstnode.buildderefimpl;
       begin
         inherited buildderefimpl;
-        astringdefderef.build(astringdef);
+        if cst_type=cst_ansistring then
+          astringdefderef.build(astringdef);
       end;
 
 
     procedure tstringconstnode.derefimpl;
       begin
         inherited derefimpl;
-        astringdef:=tdef(astringdefderef.resolve);
+        if cst_type=cst_ansistring then
+          astringdef:=tdef(astringdefderef.resolve);
       end;