Fix an exception caused by a null-string CPPPATH.

2 files changed, 22 insertions, 9 deletions

diff --git a/src/engine/SCons/Util.py b/src/engine/SCons/Util.py
index 038468f..2202abd 100644
--- a/src/engine/SCons/Util.py
+++ b/src/engine/SCons/Util.py
@@ -306,7 +306,12 @@ class VarInterpolator:
         if not dict.has_key(self.src):
             dict[self.dest] = ''
             return
-        src = self.prepareSrc(dict)
+
+        src = filter(lambda x: not x is None, self.prepareSrc(dict))
+
+        if not src:
+            dict[self.dest] = ''
+            return
 
         try:
             prefix = str(dict[self.prefix])
@@ -345,16 +350,18 @@ class DirVarInterp(VarInterpolator):
         self.fs = None
         self.Dir = None
         self.dictInstCache = {}
-        
+
     def prepareSrc(self, dict):
         src = VarInterpolator.prepareSrc(self, dict)
-	
-	def prepare(x, self=self):
-	    if not isinstance(x, SCons.Node.Node):
-		return self.fs.Dir(str(x), directory=self.dir)
-	    else:
-		return x
-	    
+
+        def prepare(x, self=self):
+            if isinstance(x, SCons.Node.Node):
+                return x
+            elif str(x):
+                return self.fs.Dir(str(x), directory=self.dir)
+            else:
+                return None
+
         return map(prepare, src)
 
     def instance(self, dir, fs):
diff --git a/src/engine/SCons/UtilTests.py b/src/engine/SCons/UtilTests.py
index 0e9f7b5..bcb93d0 100644
--- a/src/engine/SCons/UtilTests.py
+++ b/src/engine/SCons/UtilTests.py
@@ -242,6 +242,12 @@ class UtilTestCase(unittest.TestCase):
         assert dict['_INCFLAGS'][7] == '$)', \
                dict['_INCFLAGS'][7]
 
+        dict = {'CPPPATH'  : '',
+                'LIBPATH'  : '' }
+        autogenerate(dict, dir = SCons.Node.FS.default_fs.Dir('/yy'))
+        assert len(dict['_INCFLAGS']) == 0, dict['_INCFLAGS']
+        assert len(dict['_LIBDIRFLAGS']) == 0, dict['_LIBDIRFLAGS']
+
     def test_render_tree(self):
         class Node:
             def __init__(self, name, children=[]):