Add additional test coverage
Test was requested via post-commit review
diff --git a/clang/test/Sema/warn-duplicate-decl-specifier.c b/clang/test/Sema/warn-duplicate-decl-specifier.c
index d57bb86..8366f77 100644
--- a/clang/test/Sema/warn-duplicate-decl-specifier.c
+++ b/clang/test/Sema/warn-duplicate-decl-specifier.c
@@ -15,3 +15,5 @@
__attribute__((address_space(1))) // expected-warning {{multiple identical address spaces specified for type}}
int j = 12;
+volatile const volatile const int x = 1; // expected-warning {{duplicate 'const' declaration specifier}} \
+ expected-warning {{duplicate 'volatile' declaration specifier}}
