[PPL-devel] [GIT] ppl/ppl(master): Corrected a bug affecting Interval:: CC76_widening_assign(const From&, Iterator, Iterator).

[Roberto Bagnara]

Module: ppl/ppl
Branch: master
Commit: 535657baab7b4f5e6d884a7fcdc2138b1ea0797c
URL:    http://www.cs.unipr.it/git/gitweb.cgi?p=ppl/ppl.git;a=commit;h=535657baab7b4f5e6d884a7fcdc2138b1ea0797c

Author: Roberto Bagnara <bagnara at cs.unipr.it>
Date:   Fri Aug 13 15:37:24 2010 +0200

Corrected a bug affecting Interval::CC76_widening_assign(const From&, Iterator, Iterator).
This, in turn, affected Box::CC76_widening_assign(const T&, Iterator,
Iterator): lower bound would not be computed correctly when the two
iterators specify an empty list of stop points.  Many thanks to Sagar
Chaki and Arie Gurfinkel.

---

 NEWS                      |   16 ++++++++++++++++
 src/Interval.templates.hh |    8 ++++++--
 tests/Box/cc76widening.cc |   33 +++++++++++++++++++++++++++++++++
 3 files changed, 55 insertions(+), 2 deletions(-)

diff --git a/NEWS b/NEWS
index d9508f0..67c19e2 100644
--- a/NEWS
+++ b/NEWS
@@ -4,6 +4,22 @@ Parma Polyhedra Library NEWS -- history of user-visible changes
 
 
 --------------------------------------------------------------------------
+NEWS for version 0.11  (release date to be decided)
+--------------------------------------------------------------------------
+
+Bugfixes
+========
+
+o  Corrected a bug affecting methods
+
+     Box::CC76_widening_assign(const T&, Iterator, Iterator)
+     Interval::CC76_widening_assign(const From&, Iterator, Iterator)
+
+   whereby a lower bound would not be computed correctly when the two
+   iterators specify an empty list of stop points.
+
+
+--------------------------------------------------------------------------
 NEWS for version 0.11  (released on August 2, 2010)
 --------------------------------------------------------------------------
 
diff --git a/src/Interval.templates.hh b/src/Interval.templates.hh
index 456458e..eedd48e 100644
--- a/src/Interval.templates.hh
+++ b/src/Interval.templates.hh
@@ -120,8 +120,12 @@ Interval<Boundary, Info>::CC76_widening_assign(const From& y,
 	    x.lower_extend();
 	}
       }
-      else
-	x_lb = *--k;
+      else {
+        if (k != first)
+          x_lb = *--k;
+        else
+          x.lower_extend();
+      }
     }
   }
 }
diff --git a/tests/Box/cc76widening.cc b/tests/Box/cc76widening.cc
index 0c7eccf..44a6ce0 100644
--- a/tests/Box/cc76widening.cc
+++ b/tests/Box/cc76widening.cc
@@ -78,9 +78,42 @@ test02() {
   return ok;
 }
 
+bool
+test03() {
+  typedef TBox::interval_type::boundary_type tbt;
+  // No stop point indeed.
+  tbt stop_points;
+
+  Variable x(0);
+  Variable y(1);
+
+  TBox box1(2);
+  box1.add_constraint(x >= 1);
+  box1.add_constraint(x <= 4);
+
+  TBox box2(2);
+  box2.add_constraint(x >= 3);
+  box2.add_constraint(x <= 4);
+
+  print_constraints(box1, "*** box1 ***");
+  print_constraints(box2, "*** box2 ***");
+
+  box1.CC76_widening_assign(box2, &stop_points, &stop_points);
+
+  Rational_Box known_result(2);
+  known_result.add_constraint(x <= 4);
+
+  bool ok = check_result(box1, known_result);
+
+  print_constraints(box1, "*** box1.CC76_widening_assign(box2) ***");
+
+  return ok;
+}
+
 } // namespace
 
 BEGIN_MAIN
   DO_TEST(test01);
   DO_TEST(test02);
+  DO_TEST(test03);
 END_MAIN