From d54c3369b3812ce2071b7676a035732fe864fce4 Mon Sep 17 00:00:00 2001
From: Markus Triska <triska@metalevel.at>
Date: Tue, 5 Sep 2023 19:39:05 +0200
Subject: [PATCH 1/2] FIXED: countall/2 for zero solutions (#1996)

Example:

    ?- countall(false, 0).
       true.
---
 src/lib/iso_ext.pl | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/src/lib/iso_ext.pl b/src/lib/iso_ext.pl
index 0a5798ae..b6863487 100644
--- a/src/lib/iso_ext.pl
+++ b/src/lib/iso_ext.pl
@@ -370,7 +370,7 @@ countall(Goal, N) :-
     (   integer(N) ->
         (   N < 0 ->
             domain_error(not_less_than_zero, N, countall/2)
-        ;   N > 0
+        ;   true
         )
     ;   true
     ),

From 1967518fa2c5a1a625fc88f47a0f27e88f6e663d Mon Sep 17 00:00:00 2001
From: Markus Triska <triska@metalevel.at>
Date: Tue, 5 Sep 2023 19:42:55 +0200
Subject: [PATCH 2/2] FIXED: documentation of countall/2 (#1976)

---
 src/lib/iso_ext.pl | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/src/lib/iso_ext.pl b/src/lib/iso_ext.pl
index b6863487..2f1286f0 100644
--- a/src/lib/iso_ext.pl
+++ b/src/lib/iso_ext.pl
@@ -358,10 +358,10 @@ call_nth_nesting(C, ID) :-
     bb_put(ID, 0),
     bb_put(i_call_nth_counter, C).
 
-%% countall(Goal, N).
+%% countall(G_0, N).
 %
-% countall(Goal, N) counts all solutions of Goal and unifies N with
-% this number of solutions. This predicate always succeeds once.
+% countall(G_0, N) is true iff N unifies with the total number of
+% answers of call(G_0).
 
 :- meta_predicate(countall(0, ?)).