[clang] [clang] Fix crash in DiagnoseMissingSemiAfterTagDefinition for annot_template_id (PR #208119)

[Corentin Jabot via cfe-commits]

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@@ -0,0 +1,14 @@
+// RUN: %clang_cc1 -std=c++23 -fsyntax-only -verify %s
+
+// Ensure no crash when DiagnoseMissingSemiAfterTagDefinition encounters an
+// annot_template_id not followed by '::'.
+
+namespace N {
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cor3ntin wrote:

```suggestion
namespace GH207992 {
```

https://github.com/llvm/llvm-project/pull/208119