Index: lib/Format/TokenAnnotator.cpp
===================================================================
--- lib/Format/TokenAnnotator.cpp
+++ lib/Format/TokenAnnotator.cpp
@@ -694,8 +694,9 @@
     } else if (Current.isOneOf(tok::kw_return, tok::kw_throw)) {
       Contexts.back().IsExpression = true;
     } else if (Current.is(tok::l_paren) && !Line.MustBeDeclaration &&
-               !Line.InPPDirective && Current.Previous &&
-               Current.Previous->isNot(tok::kw_decltype)) {
+               !Line.InPPDirective &&
+               (!Current.Previous ||
+                Current.Previous->isNot(tok::kw_decltype))) {
       bool ParametersOfFunctionType =
           Current.Previous && Current.Previous->is(tok::r_paren) &&
           Current.Previous->MatchingParen &&
Index: unittests/Format/FormatTest.cpp
===================================================================
--- unittests/Format/FormatTest.cpp
+++ unittests/Format/FormatTest.cpp
@@ -4754,6 +4754,8 @@
   // FIXME: single value wrapped with paren will be treated as cast.
   verifyFormat("void f(int i = (kValue)*kMask) {}");
 
+  verifyFormat("{ (void)F; }");
+
   // Don't break after a cast's
   verifyFormat("int aaaaaaaaaaaaaaaaaaaaaaaaaaa =\n"
                "    (aaaaaaaaaaaaaaaaaaaaaaaaaa *)(aaaaaaaaaaaaaaaaaaaaaa +\n"