Improve the unused-value check to look into comma expressions and filter out
voids in sub-expressions.  Patch by Mike M!

Fixes PR4806.

llvm-svn: 98335
diff --git a/clang/test/SemaCXX/decl-expr-ambiguity.cpp b/clang/test/SemaCXX/decl-expr-ambiguity.cpp
index 81f6839..4243c1c 100644
--- a/clang/test/SemaCXX/decl-expr-ambiguity.cpp
+++ b/clang/test/SemaCXX/decl-expr-ambiguity.cpp
@@ -10,7 +10,7 @@
   int(a)++; // expected-error {{expression is not assignable}}
   __extension__ int(a)++; // expected-error {{expression is not assignable}}
   __typeof(int)(a,5)<<a; // expected-error {{function-style cast to a builtin type can only take one argument}}
-  void(a), ++a; // expected-warning {{expression result unused}}
+  void(a), ++a;
   if (int(a)+1) {}
   for (int(a)+1;;) {} // expected-warning {{expression result unused}}
   a = sizeof(int()+1);