checker should be called after preprocessing (obs from Roberto Bagnara).

pl/boot.yap

@@ -461,9 +461,14 @@ true :- true.
 	 '$$compile'(G1, G0, N, HeadMod).
 
  '$prepare_term'(G, V, Pos, G0, G1, BodyMod, SourceMod, Source) :-
-	 ( get_value('$syntaxcheckflag',on) ->
-		 '$check_term'(Source, V, Pos, BodyMod) ; true ),
-	 '$precompile_term'(G, G0, G1, BodyMod, SourceMod).
+	 '$precompile_term'(G, G0, G1, BodyMod, SourceMod),
+	 (
+	     get_value('$syntaxcheckflag',on)
+          ->
+	     '$check_term'(G0, V, Pos, Source, BodyMod)
+	 ;
+	     true 
+	 ).
 
  % process an input clause
  '$$compile'(G, G0, L, Mod) :-

pl/checker.yap

@@ -120,20 +120,22 @@ no_style_check([H|T]) :- no_style_check(H), no_style_check(T).
 	'$values'('$syntaxcheckmultiple',O,N).
 
 
-'$check_term'(T,_,P,M) :-
+'$check_term'(T,_,P,_Source,M) :-
 	get_value('$syntaxcheckdiscontiguous',on),
 	'$xtract_head'(T,M,NM,_,F,A),
 	'$handle_discontiguous'(F,A,NM), fail.
-'$check_term'(T,_,P,M) :-
+'$check_term'(T,_,P,_Source,M) :-
 	get_value('$syntaxcheckmultiple',on),
 	'$xtract_head'(T,M,NM,_,F,A),
 	'$handle_multiple'(F,A,NM), fail.
-'$check_term'(T,VL,P,_) :-
+'$check_term'(T,VL,P,_Source,_) :-
 	get_value('$syntaxchecksinglevar',on),
 	( '$chk_binding_vars'(T),
-	  '$sv_list'(VL,Sv) ->
-	  '$sv_warning'(Sv,T) ), fail.
-'$check_term'(_,_,_,_).
+	  '$sv_list'(VL,Sv)
+        ->
+	  '$sv_warning'(Sv,T)
+         ), fail.
+'$check_term'(_,_,_,_,_).
 
 '$chk_binding_vars'(V) :- var(V), !, V = '$V'(_).
 '$chk_binding_vars'('$V'(off)) :- !.