[clang] [Clang][Parser] Report error when attribute missing ]] followed by ;; (PR #187580)

[Erich Keane via cfe-commits]

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@@ -0,0 +1,15 @@
+// RUN: %clang_cc1 -fsyntax-only -verify %s
+
+// expected-note at +1 {{to match this '{'}}
+void a(int i) {
+    switch(i) {
+        case 1:
+  // expected-error at +2 {{expected ']'}}
+  // expected-error at +3 {{expected ']'}}
+  [[fallthrough;;
+        case 2:
+        ;
+    };
+   // expected-error at +2 {{expected statement}}
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erichkeane wrote:

This is a weird degredation of behavior.  What causes this?

https://github.com/llvm/llvm-project/pull/187580