fix tests, use '$first_answer' to print indentation before errors (#1408)

src/loader.pl

@@ -18,7 +18,14 @@
 
 
 write_error(Error) :-
-    write('   '),
+    % '$fetch_global_var' is the core system call of bb_get/2, but
+    % bb_get may not exist when write_error is first called, so fall
+    % back on '$fetch_global_var'.
+    (  '$fetch_global_var'('$first_answer', false) ->
+       true
+    ;  write('   ') % if '$first_answer' isn't defined yet or true,
+                    % print indentation.
+    ),
     (  nonvar(Error),
        functor(Error, error, 2) ->
        writeq(Error)

src/machine/project_attributes.pl

@@ -10,8 +10,7 @@ project_attributes(QueryVars, AttrVars) :-
        ;  E = error(evaluation_error((Module:project_attributes)/2), _)
        )  ->
        true
-    ;  write_term('caught: ', [quoted(false)]),
-       writeq(E),
+    ;  loader:write_error(E),
        nl
     ).
 
@@ -34,8 +33,7 @@ call_attribute_goals([Module|Modules], GoalCaller, AttrVars) :-
 '$print_attribute_goals_exception'(Module, E) :-
     (  E = error(evaluation_error((Module:attribute_goals)/3), attribute_goals/3)
     -> true
-    ;  write_term('caught: ', [quoted(false)]),
-       writeq(E),
+    ;  loader:write_error(E),
        nl
     ).
 

src/tests/clpz/test_clpz.pl

@@ -100,7 +100,7 @@ run :-
             Dss
         ),
         E,
-        (   write('caught: '), write(E), nl,
+        (   loader:write_error(E), nl,
             portray_clause([N, Settings, Vs, Gs4, Dss]), nl,
             false
         )

src/toplevel.pl

@@ -134,6 +134,7 @@ run_goals([Goal|_]) :-
     halt.
 
 repl :-
+    bb_put('$first_answer', true),
     catch(read_and_match, E, print_exception(E)),
     false. %% this is for GC, until we get actual GC.
 repl :-
@@ -198,9 +199,8 @@ submit_query_and_print_results(Term0, VarList) :-
                     % in the first argument, which is done by call/N
     ;  expand_goal(Term0, user, Term)
     ),
-    setup_call_cleanup(bb_put('$first_answer', true),
-                       submit_query_and_print_results_(Term, VarList),
-                       bb_put('$first_answer', false)).
+    bb_put('$first_answer', true),
+    submit_query_and_print_results_(Term, VarList).
 
 
 needs_bracketing(Value, Op) :-