* shortstring should be prefered when converting string-string

tests/tbs/tb0429.pp

@@ -0,0 +1,21 @@
+
+procedure lowercase(c:char);overload;
+begin
+  writeln('char');
+end;
+procedure lowercase(c:shortstring);overload;
+begin
+  writeln('short');
+end;
+procedure lowercase(c:ansistring);overload;
+begin
+  writeln('ansi');
+end;
+
+var
+  w : widestring;
+begin
+  { this should choosse the shortstring version }
+  lowercase(w);
+end.
+