diff --git a/gcc/cp/ChangeLog b/gcc/cp/ChangeLog
index 2c3efe82556..2cd295b5b53 100644
--- a/gcc/cp/ChangeLog
+++ b/gcc/cp/ChangeLog
@@ -1,3 +1,8 @@
+2012-12-11  Jakub Jelinek  <jakub@redhat.com>
+
+	PR c++/55643
+	* expr.c (mark_exp_read): Handle FLOAT_EXPR similarly to NOP_EXPR.
+
 2012-12-11  Jason Merrill  <jason@redhat.com>
 
 	PR c++/54416
diff --git a/gcc/cp/expr.c b/gcc/cp/expr.c
index ede4725da2f..c521e7d930f 100644
--- a/gcc/cp/expr.c
+++ b/gcc/cp/expr.c
@@ -131,6 +131,7 @@ mark_exp_read (tree exp)
     CASE_CONVERT:
     case ADDR_EXPR:
     case INDIRECT_REF:
+    case FLOAT_EXPR:
       mark_exp_read (TREE_OPERAND (exp, 0));
       break;
     case COMPOUND_EXPR:
diff --git a/gcc/testsuite/ChangeLog b/gcc/testsuite/ChangeLog
index e6d4f69d4e3..ef71057069e 100644
--- a/gcc/testsuite/ChangeLog
+++ b/gcc/testsuite/ChangeLog
@@ -1,5 +1,8 @@
 2012-12-11  Jakub Jelinek  <jakub@redhat.com>
 
+	PR c++/55643
+	* g++.dg/warn/Wunused-var-19.C: New test.
+
 	* g++.dg/asan/asan_test.C: Link -lasan before -lpthread.
 
 2012-12-11  Eric Botcazou  <ebotcazou@adacore.com>
diff --git a/gcc/testsuite/g++.dg/warn/Wunused-var-19.C b/gcc/testsuite/g++.dg/warn/Wunused-var-19.C
new file mode 100644
index 00000000000..4d26b368143
--- /dev/null
+++ b/gcc/testsuite/g++.dg/warn/Wunused-var-19.C
@@ -0,0 +1,26 @@
+// PR c++/55643
+// { dg-do compile }
+// { dg-options "-std=c++11 -Wunused" }
+
+enum class E { e = 123 };
+
+int
+foo ()
+{
+  E x = E::e;
+  return (double) x;
+}
+
+int
+bar ()
+{
+  E x = E::e;
+  return (long double) x;
+}
+
+int
+baz ()
+{
+  E x = E::e;
+  return (float) x;
+}