--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/gcc/testsuite/gcc.dg/c2x-attr-syntax-3.c	Thu Feb 13 11:34:05 2020 +0900
@@ -0,0 +1,56 @@
+/* Test C2x attribute syntax.  Invalid uses of attributes.  */
+/* { dg-do compile } */
+/* { dg-options "-std=c2x -pedantic-errors" } */
+
+/* Prefix attributes not allowed on declarations without declarators.  */
+
+[[]] struct s { int a; }; /* { dg-error "empty declaration" } */
+
+[[]] union u { int a; }; /* { dg-error "empty declaration" } */
+
+void
+f1 (void)
+{
+  [[]] struct t { int a; }; /* { dg-error "empty declaration" } */
+}
+
+/* Prefix attributes not allowed on _Static_assert.  */
+
+[[]] _Static_assert (1); /* { dg-error "expected" } */
+
+void
+f2 (void)
+{
+  [[]] _Static_assert (1); /* { dg-error "expected" } */
+}
+
+/* Declarations, including attribute declarations, cannot appear after
+   labels.  */
+
+void
+f3 (void)
+{
+ x: [[]];; /* { dg-error "can only be part of a statement" } */
+}
+
+/* Prefix attributes cannot appear on type names.  */
+
+int z = sizeof ([[]] int); /* { dg-error "expected" } */
+
+/* Attributes are not allowed after struct, union or enum, except when
+   the type contents are being defined or the declaration is just
+   "struct-or-union atribute-specifier-sequence identifier;".  */
+
+const struct [[]] s2; /* { dg-warning "useless type qualifier" } */
+/* { dg-error "invalid use of attributes in empty declaration" "invalid" { target *-*-* } .-1 } */
+
+const union [[]] u2; /* { dg-warning "useless type qualifier" } */
+/* { dg-error "invalid use of attributes in empty declaration" "invalid" { target *-*-* } .-1 } */
+
+struct [[]] s3 *sv; /* { dg-error "expected" } */
+
+union [[]] u3 *uv; /* { dg-error "expected" } */
+
+enum e { E1 };
+
+enum [[]] e *ev; /* { dg-error "expected" } */