--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/gcc/testsuite/c-c++-common/dfp/usual-arith-conv-const.c	Fri Oct 27 22:46:09 2017 +0900
@@ -0,0 +1,32 @@
+/* { dg-do compile } */
+
+/* Test various conversions involving decimal floating types. */
+
+#include "dfp-dbg.h"
+
+/* Assertion that constant C is of type T.  */
+#define ASSERT_CONST_TYPE(C, T)                 \
+        do {                                    \
+          typedef T type;                       \
+          typedef type **typepp;                \
+          typedef __typeof__((C)) ctype;        \
+          typedef ctype **ctypepp;              \
+          typepp x = 0;                         \
+          ctypepp y = 0;                        \
+          x = y;                                \
+          y = x;                                \
+        } while (0)
+
+int
+main ()
+{
+  ASSERT_CONST_TYPE (3 + 2.1df, _Decimal32); /* { dg-bogus "assignment from incompatible pointer type" } */
+  ASSERT_CONST_TYPE (1.3df + 2, _Decimal32); /* { dg-bogus "assignment from incompatible pointer type" } */
+  ASSERT_CONST_TYPE (56U - 55.0dd, _Decimal64); /* { dg-bogus "assignment from incompatible pointer type" } */
+  ASSERT_CONST_TYPE (5 * .2DL, _Decimal128); /* { dg-bogus "assignment from incompatible pointer type" } */
+  ASSERT_CONST_TYPE (.88dl / 2L, _Decimal128); /* { dg-bogus "assignment from incompatible pointer type" } */
+  ASSERT_CONST_TYPE (.114df - 1.6dd, _Decimal64); /* { dg-bogus "assignment from incompatible pointer type" } */
+  ASSERT_CONST_TYPE (3L - 1 + .55df, _Decimal32); /* { dg-bogus "assignment from incompatible pointer type" } */
+
+  return 0;
+}