[gnumeric] internals: add some preconditions.

[Morten Welinder <mortenw src gnome org>]

commit a5296350025289c007a9d2423c073f4b4214f05d
Author: Morten Welinder <terra gnome org>
Date:   Thu Mar 3 13:51:07 2011 -0500

    internals: add some preconditions.

 ChangeLog   |    6 ++++++
 src/expr.c  |    2 ++
 src/value.c |    6 +++++-
 3 files changed, 13 insertions(+), 1 deletions(-)
---
diff --git a/ChangeLog b/ChangeLog
index 8d79b1a..cb6540a 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -6,6 +6,12 @@
 	* schemas/org.gnome.gnumeric.gschema.xml.in.in: ditto.
 	* schemas/org.gnome.gnumeric.plugin.gschema.xml.in.in: ditto.
 
+2011-03-03  Morten Welinder  <terra gnome org>
+
+	* src/value.c (value_new_string_str): Add precondition.
+
+	* src/expr.c (gnm_expr_new_constant): Add precondition.
+
 2011-03-01  Morten Welinder  <terra gnome org>
 
 	* src/gnumeric-gconf.c (get_node): Handle absolute keys, assuming
diff --git a/src/expr.c b/src/expr.c
index 93b8a1f..2fb2f15 100644
--- a/src/expr.c
+++ b/src/expr.c
@@ -77,6 +77,8 @@ gnm_expr_new_constant (GnmValue *v)
 {
 	GnmExprConstant *ans;
 
+	g_return_val_if_fail (v != NULL, NULL);
+
 	ans = CHUNK_ALLOC (GnmExprConstant, expression_pool_small);
 	if (!ans)
 		return NULL;
diff --git a/src/value.c b/src/value.c
index 26fd500..4821e7b 100644
--- a/src/value.c
+++ b/src/value.c
@@ -228,7 +228,11 @@ value_error_classify (GnmValue const *v)
 GnmValue *
 value_new_string_str (GOString *str)
 {
-	GnmValueStr *v = CHUNK_ALLOC (GnmValueStr, value_string_pool);
+	GnmValueStr *v;
+
+	g_return_val_if_fail (str != NULL, NULL);
+
+	v = CHUNK_ALLOC (GnmValueStr, value_string_pool);
 	*((GnmValueType *)&(v->type)) = VALUE_STRING;
 	v->fmt = NULL;
 	v->val = str;