--- /dev/null
+// RUN: %clang_cc1 -std=c++1z -verify %s
+
+void f(int n) {
+ switch (n) {
+ case 0:
+ n += 1;
+ [[fallthrough]]; // ok
+ case 1:
+ if (n) {
+ [[fallthrough]]; // ok
+ } else {
+ return;
+ }
+ case 2:
+ for (int n = 0; n != 10; ++n)
+ [[fallthrough]]; // expected-error {{does not directly precede switch label}}
+ case 3:
+ while (true)
+ [[fallthrough]]; // expected-error {{does not directly precede switch label}}
+ case 4:
+ while (false)
+ [[fallthrough]]; // expected-error {{does not directly precede switch label}}
+ case 5:
+ do [[fallthrough]]; while (true); // expected-error {{does not directly precede switch label}}
+ case 6:
+ do [[fallthrough]]; while (false); // expected-error {{does not directly precede switch label}}
+ case 7:
+ switch (n) {
+ case 0:
+ // FIXME: This should be an error, even though the next thing we do is to
+ // fall through in an outer switch statement.
+ [[fallthrough]];
+ }
+ case 8:
+ [[fallthrough]]; // expected-error {{does not directly precede switch label}}
+ goto label;
+ label:
+ case 9:
+ n += 1;
+ case 10: // no warning, -Wimplicit-fallthrough is not enabled in this test, and does not need to
+ // be enabled for these diagnostics to be produced.
+ break;
+ }
+}
+
+[[fallthrough]] typedef int n; // expected-error {{'fallthrough' attribute cannot be applied to a declaration}}
+typedef int [[fallthrough]] n; // expected-error {{'fallthrough' attribute cannot be applied to types}}
+typedef int n [[fallthrough]]; // expected-error {{'fallthrough' attribute cannot be applied to a declaration}}
+
+enum [[fallthrough]] E {}; // expected-error {{'fallthrough' attribute cannot be applied to a declaration}}
+class [[fallthrough]] C {}; // expected-error {{'fallthrough' attribute cannot be applied to a declaration}}
+
+[[fallthrough]] // expected-error {{'fallthrough' attribute cannot be applied to a declaration}}
+void g() {
+ [[fallthrough]] int n; // expected-error {{'fallthrough' attribute cannot be applied to a declaration}}
+ [[fallthrough]] ++n; // expected-error-re {{{{^}}fallthrough attribute is only allowed on empty statements}}
+
+ switch (n) {
+ // FIXME: This should be an error.
+ [[fallthrough]];
+ return;
+
+ case 0:
+ [[fallthrough, fallthrough]]; // expected-error {{multiple times}}
+ case 1:
+ [[fallthrough(0)]]; // expected-error {{argument list}}
+ case 2:
+ break;
+ }
+}