[gnumeric] solver: be paranoid about error values.

[Morten Welinder <mortenw src gnome org>]

commit 0fa21f70746966b49d461e32d4154446cf2add30
Author: Morten Welinder <terra gnome org>
Date:   Mon May 24 22:31:31 2010 -0400

    solver: be paranoid about error values.

 src/tools/ChangeLog    |    5 +++++
 src/tools/gnm-solver.c |    6 ++++++
 2 files changed, 11 insertions(+), 0 deletions(-)
---
diff --git a/src/tools/ChangeLog b/src/tools/ChangeLog
index 358dbe2..8641c41 100644
--- a/src/tools/ChangeLog
+++ b/src/tools/ChangeLog
@@ -1,3 +1,8 @@
+2010-05-24  Morten Welinder  <terra gnome org>
+
+	* src/tools/gnm-solver.c (gnm_solver_check_constraints): Check
+	that the objective value is a number.
+
 2010-05-24 Andreas J. Guelzow <aguelzow pyrshep ca>
 
 	* analysis-wilcoxon-mann-whitney.c: new
diff --git a/src/tools/gnm-solver.c b/src/tools/gnm-solver.c
index 43a9dd4..79dbed8 100644
--- a/src/tools/gnm-solver.c
+++ b/src/tools/gnm-solver.c
@@ -961,6 +961,7 @@ gnm_solver_check_constraints (GnmSolver *solver)
 {
 	GSList *l;
 	GnmSolverParameters *sp = solver->params;
+	GnmCell *target_cell;
 
 	if (sp->options.assume_non_negative ||
 	    sp->options.assume_discrete) {
@@ -1026,6 +1027,11 @@ gnm_solver_check_constraints (GnmSolver *solver)
 		}
 	}
 
+	target_cell = gnm_solver_param_get_target_cell (sp);
+	gnm_cell_eval (target_cell);
+	if (!target_cell || !VALUE_IS_NUMBER (target_cell->value))
+		return FALSE;
+
 	return TRUE;
 }