Add accidentally forgotten testcase from r262881.

llvm-svn: 262882

clang/test/CXX/dcl.dcl/dcl.attr/dcl.attr.fallthrough/p1.cpp

@@ -0,0 +1,70 @@
+// 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;
+  }
+}