# HG changeset patch
# User Matt Mackall <mpm@selenic.com>
# Date 2010-06-18 22:34:13
# Node ID e5a2134c083b223bd2998b6694e430e4999caee3
# Parent  c040847539905c3f9c8b417586128695c72f3dd4

revset: nicer exception for empty queries

diff --git a/mercurial/revset.py b/mercurial/revset.py
--- a/mercurial/revset.py
+++ b/mercurial/revset.py
@@ -546,6 +546,8 @@ def optimize(x, small):
 parse = parser.parser(tokenize, elements).parse
 
 def match(spec):
+    if not spec:
+        raise error.ParseError(_("empty query"))
     tree = parse(spec)
     weight, tree = optimize(tree, True)
     def mfunc(repo, subset):