diff --git a/mercurial/commands.py b/mercurial/commands.py
--- a/mercurial/commands.py
+++ b/mercurial/commands.py
@@ -1214,7 +1214,7 @@ def debugpushkey(ui, repopath, namespace
 def debugrevspec(ui, repo, expr):
     '''parse and apply a revision specification'''
     if ui.verbose:
-        tree = revset.parse(expr)
+        tree = revset.parse(expr)[0]
         ui.note(tree, "\n")
     func = revset.match(expr)
     for c in func(repo, range(len(repo))):
diff --git a/mercurial/parser.py b/mercurial/parser.py
--- a/mercurial/parser.py
+++ b/mercurial/parser.py
@@ -78,7 +78,9 @@ class parser(object):
         'generate a parse tree from a message'
         self._iter = self._tokenizer(message)
         self._advance()
-        return self._parse()
+        res = self._parse()
+        token, value, pos = self.current
+        return res, pos
     def eval(self, tree):
         'recursively evaluate a parse tree using node methods'
         if not isinstance(tree, tuple):
diff --git a/mercurial/revset.py b/mercurial/revset.py
--- a/mercurial/revset.py
+++ b/mercurial/revset.py
@@ -810,7 +810,9 @@ parse = parser.parser(tokenize, elements
 def match(spec):
     if not spec:
         raise error.ParseError(_("empty query"))
-    tree = parse(spec)
+    tree, pos = parse(spec)
+    if (pos != len(spec)):
+        raise error.ParseError("invalid token", pos)
     weight, tree = optimize(tree, True)
     def mfunc(repo, subset):
         return getset(repo, subset, tree)
diff --git a/mercurial/templater.py b/mercurial/templater.py
--- a/mercurial/templater.py
+++ b/mercurial/templater.py
@@ -69,7 +69,6 @@ def tokenizer(data):
         else:
             raise error.ParseError(_("syntax error"), pos)
         pos += 1
-    data[2] = pos
     yield ('end', None, pos)
 
 def compiletemplate(tmpl, context):
@@ -91,8 +90,8 @@ def compiletemplate(tmpl, context):
             parsed.append(("string", tmpl[pos:n]))
 
         pd = [tmpl, n + 1, stop]
-        parsed.append(p.parse(pd))
-        pos = pd[2]
+        parseres, pos = p.parse(pd)
+        parsed.append(parseres)
 
     return [compileexp(e, context) for e in parsed]
 
diff --git a/tests/test-revset.t b/tests/test-revset.t
--- a/tests/test-revset.t
+++ b/tests/test-revset.t
@@ -356,3 +356,10 @@ issue2437
   9
   $ log 'ancestors(8) and (heads(branch("-a-b-c-")) or heads(branch(é)))'
   4
+
+issue2654: report a parse error if the revset was not completely parsed
+
+  $ log '1 OR 2'
+  hg: parse error at 2: invalid token
+  [255]
+