1 files changed, 31 insertions, 0 deletions

diff --git a/meta/lib/oe/types.py b/meta/lib/oe/types.py
index ea31cf4219..ea53df9bf2 100644
--- a/meta/lib/oe/types.py
+++ b/meta/lib/oe/types.py
@@ -40,6 +40,31 @@ def choice(value, choices):
                          (value, choices))
     return value
 
+class NoMatch(object):
+    """Stub python regex pattern object which never matches anything"""
+    def findall(self, string, flags=0):
+        return None
+
+    def finditer(self, string, flags=0):
+        return None
+
+    def match(self, flags=0):
+        return None
+
+    def search(self, string, flags=0):
+        return None
+
+    def split(self, string, maxsplit=0):
+        return None
+
+    def sub(pattern, repl, string, count=0):
+        return None
+
+    def subn(pattern, repl, string, count=0):
+        return None
+
+NoMatch = NoMatch()
+
 def regex(value, regexflags=None):
     """OpenEmbedded 'regex' type
 
@@ -59,6 +84,12 @@ def regex(value, regexflags=None):
             except AttributeError:
                 raise ValueError("Invalid regex flag '%s'" % flag)
 
+    if not value:
+        # Let's ensure that the default behavior for an undefined or empty
+        # variable is to match nothing. If the user explicitly wants to match
+        # anything, they can match '.*' instead.
+        return NoMatch
+
     try:
         return re.compile(value, flagval)
     except re.error, exc: