re PR c++/84488 (Incorrect "set but not used" warning for static_cast<Enum>(double))

	PR c++/84488
	* g++.dg/warn/Wunused-var-30.C: New test.

From-SVN: r257850

gcc/testsuite/ChangeLog

+2018-02-20  Jakub Jelinek  <jakub@redhat.com>
+
+	PR c++/84488
+	* g++.dg/warn/Wunused-var-30.C: New test.
+
 2018-02-20  Richard Sandiford  <richard.sandiford@linaro.org>
 
 	PR tree-optimization/84419

gcc/testsuite/g++.dg/warn/Wunused-var-30.C

+// PR c++/84488
+// { dg-do compile }
+// { dg-options "-Wunused-but-set-variable" }
+
+int
+foo ()
+{
+  enum E { A, B, C, D };
+  double r = 1.0;		// { dg-bogus "set but not used" }
+  return static_cast<E>(r);
+}