Functions and predicates over Boolean now work with --check-models and output correct

models for such functions (though they are somewhat ugly at present).

There's still a problem with model extraction, but it's not Boolean terms' fault.
Sometimes checkModel() can report that the model is just fine, but if a user extracts
values with getValue(), they find problems with the model (i.e., it doesn't satisfy some
assertions).  This appears to be due to an asymmetry between how checkModel() works and
how Model::getValue() works.  I'll open a bugzilla report to discuss this after thinking
some more on it.

(this commit was certified error- and warning-free by the test-and-commit script.)

1 files changed, 6 insertions, 2 deletions

diff --git a/src/expr/expr_template.cpp b/src/expr/expr_template.cpp
index bc7f0f47c..ed643b830 100644
--- a/src/expr/expr_template.cpp
+++ b/src/expr/expr_template.cpp
@@ -53,8 +53,12 @@ std::ostream& operator<<(std::ostream& out, const TypeCheckingException& e) {
 }
 
 std::ostream& operator<<(std::ostream& out, const Expr& e) {
-  ExprManagerScope ems(*e.getExprManager());
-  return out << e.getNode();
+  if(e.isNull()) {
+    return out << "null";
+  } else {
+    ExprManagerScope ems(*e.getExprManager());
+    return out << e.getNode();
+  }
 }
 
 TypeCheckingException::TypeCheckingException(const TypeCheckingException& t) throw() :