1 files changed, 34 insertions, 3 deletions

diff --git a/Source/cmGeneratorExpressionEvaluator.cxx b/Source/cmGeneratorExpressionEvaluator.cxx
index c609000..102927e 100644
--- a/Source/cmGeneratorExpressionEvaluator.cxx
+++ b/Source/cmGeneratorExpressionEvaluator.cxx
@@ -66,6 +66,8 @@ static const struct ZeroNode : public cmGeneratorExpressionNode
 
   virtual bool GeneratesContent() const { return false; }
 
+  virtual bool AcceptsSingleArbitraryContentParameter() const { return true; }
+
   std::string Evaluate(const std::vector<std::string> &,
                        cmGeneratorExpressionContext *,
                        const GeneratorExpressionContent *,
@@ -642,6 +644,20 @@ std::string GeneratorExpressionContent::Evaluate(
 
   if (!node->GeneratesContent())
     {
+    if (node->AcceptsSingleArbitraryContentParameter())
+      {
+      if (this->ParamChildren.empty())
+        {
+        reportError(context, this->GetOriginalExpression(),
+                  "$<" + identifier + "> expression requires a parameter.");
+        }
+      }
+    else
+      {
+      std::vector<std::string> parameters;
+      this->EvaluateParameters(node, identifier, context, dagChecker,
+                               parameters);
+      }
     return std::string();
     }
 
@@ -677,6 +693,23 @@ std::string GeneratorExpressionContent::Evaluate(
     }
 
   std::vector<std::string> parameters;
+  this->EvaluateParameters(node, identifier, context, dagChecker, parameters);
+  if (context->HadError)
+    {
+    return std::string();
+    }
+
+  return node->Evaluate(parameters, context, this, dagChecker);
+}
+
+//----------------------------------------------------------------------------
+std::string GeneratorExpressionContent::EvaluateParameters(
+                                const cmGeneratorExpressionNode *node,
+                                const std::string &identifier,
+                                cmGeneratorExpressionContext *context,
+                                cmGeneratorExpressionDAGChecker *dagChecker,
+                                std::vector<std::string> &parameters) const
+{
   {
   std::vector<std::vector<cmGeneratorExpressionEvaluator*> >::const_iterator
                                         pit = this->ParamChildren.begin();
@@ -732,10 +765,8 @@ std::string GeneratorExpressionContent::Evaluate(
     {
     reportError(context, this->GetOriginalExpression(), "$<" + identifier
                       + "> expression requires at least one parameter.");
-    return std::string();
     }
-
-  return node->Evaluate(parameters, context, this, dagChecker);
+  return std::string();
 }
 
 //----------------------------------------------------------------------------