Fixes after review

  * Rename predicate cut_contained to goal_sanitized
  * Apply wrapping to both Then_0 and Else_0 branches of if_/3
  * Apply cut and invalid goal detection to left argument of (_ -> B) term.

src/lib/reif.pl

@@ -24,7 +24,7 @@
 */
 
 :- use_module(library(dif)).
-:- use_module(library(loader), [cut_contained/2]).
+:- use_module(library(loader), [goal_sanitized/2]).
 
 :- meta_predicate(if_(1, 0, 0)).
 :- meta_predicate(cond_t(1, 0, ?)).
@@ -99,8 +99,9 @@
 
 %
 user:goal_expansion(if_(If_1, Then_0, Else_0), G_0) :-
-   cut_contained(Then_0, SanitizedThen_0),
-   ugoal_expansion(if_(If_1, SanitizedThen_0, Else_0), G_0).
+   goal_sanitized(Then_0, SanitizedThen_0),
+   goal_sanitized(Else_0, SanitizedElse_0),
+   ugoal_expansion(if_(If_1, SanitizedThen_0, SanitizedElse_0), G_0).
 
 %
 %

src/loader.pl

@@ -9,7 +9,7 @@
                    use_module/1,
                    use_module/2,
                    current_module/1,
-                   cut_contained/2
+                   goal_sanitized/2
                   ]).
 
 :- use_module(library(error)).
@@ -44,7 +44,10 @@
     '$fail'.
 
 
-%% cut_contained(?G_0, ?S_0).
+never(_) :- fail.
+
+
+%% goal_sanitized(?G_0, ?S_0).
 %
 % Both `G_0` and `S_0` are valid callable terms having the same meaning, but
 % additionally `S_0` is safe to be called in combination with surrounding
@@ -56,13 +59,13 @@
 % choice points generated by `b`, but since `S_0 = call((a,!))` then
 % `b, call((a,!))` is safe.
 %
-% TODO: Should it be marked with meta_predicate(cut_contained(:,-))?
+% TODO: Should it be marked with meta_predicate(goal_sanitized(:,-))?
 %
-cut_contained(G, S) :-
-    catch(cut_contained_aux(G, S), stop(_), false).
+goal_sanitized(G, S) :-
+    catch(goal_sanitized_aux(G, S), stop(_), false).
 
-cut_contained_aux(G, call(G)) :-    cuts_outside(G).
-cut_contained_aux(G,      G ) :- \+ cuts_outside(G).
+goal_sanitized_aux(G, call(G)) :-    cuts_outside(G).
+goal_sanitized_aux(G,      G ) :- \+ cuts_outside(G).
 
 
 %% cuts_outside(?G_0).
@@ -74,14 +77,18 @@
 % removes choice points generated by `a`, but fails for `a, (! -> b)` and
 % `a, \+ \+ !`.
 %
-cuts_outside(G) :- callable_term(G), cuts_outside_aux(G).
+cuts_outside(G_0) :- cuts_outside(G_0, =(!)).
+
+%% cuts_outside(?G_0, +StopCondition_1).
+%
+cuts_outside(G, C_1) :- callable_term(G), cuts_outside_aux(G, C_1).
 
-cuts_outside_aux(!).
-cuts_outside_aux(M:A) :- module_name(M), cuts_outside(A).
-cuts_outside_aux((A,B))  :- cuts_outside(B); cuts_outside(A).
-cuts_outside_aux((A;B))  :- cuts_outside(B); cuts_outside(A).
+cuts_outside_aux(G, C_1) :- call(C_1, G).
+cuts_outside_aux(M:A, C_1) :- module_name(M), cuts_outside(A, C_1).
+cuts_outside_aux((A,B), C_1)  :- cuts_outside(B, C_1); cuts_outside(A, C_1).
+cuts_outside_aux((A;B), C_1)  :- cuts_outside(B, C_1); cuts_outside(A, C_1).
 % FIXME: There is an issue with `C, (! -> B)` construct, see #2739
-cuts_outside_aux((_->B)) :- cuts_outside(B).
+cuts_outside_aux((A->B), C_1) :- cuts_outside(A, loader:never); cuts_outside(B, C_1).
 
 
 module_name(M) :-

src/tests/reif.pl

@@ -127,18 +127,19 @@
         catch((cuts_outside(_:!),false), E3, E3  = stop(type_error(atom,_))),
         (G0 = a(G0), catch((cuts_outside(G0),false), E4, E4 = stop(type_error(acyclic_term,_)))),
         (G1 = m:G1,  catch((cuts_outside(G1),false), E5, E5 = stop(type_error(acyclic_term,_)))),
-        (cut_contained(a, X0), X0 == a),
-        (cut_contained(!, X1), X1 == call(!)),
-        (cut_contained((a,b;c,d), X2), X2 == (a,b;c,d)),
-        (cut_contained((\+ \+ a), X3), X3 == (\+ \+ a)),
+        catch((cuts_outside((6->a)),false),   E6, E6 == stop(type_error(callable,6))),
+        (goal_sanitized(a, X0), X0 == a),
+        (goal_sanitized(!, X1), X1 == call(!)),
+        (goal_sanitized((a,b;c,d), X2), X2 == (a,b;c,d)),
+        (goal_sanitized((\+ \+ a), X3), X3 == (\+ \+ a)),
         % Questionable test case, see #2739
-        (cut_contained((!,a->c;d), X4), X4 == (!,a->c;d)),
-        (cut_contained((x,a->!;d), X5), X5 == call((x,a->!;d))),
-        (cut_contained((a,b,c,!), X6), X6 == call((a,b,c,!))),
-        \+ cut_contained(0, _),
-        \+ cut_contained(_, _),
-        \+ cut_contained((a,_), _),
-        \+ cut_contained((a,b;1), _)
+        (goal_sanitized((!,a->c;d), X4), X4 == (!,a->c;d)),
+        (goal_sanitized((x,a->!;d), X5), X5 == call((x,a->!;d))),
+        (goal_sanitized((a,b,c,!), X6), X6 == call((a,b,c,!))),
+        \+ goal_sanitized(0, _),
+        \+ goal_sanitized(_, _),
+        \+ goal_sanitized((a,_), _),
+        \+ goal_sanitized((a,b;1), _)
     ]),
     phrase(format_("callable cut: ~q", [T]), W).