[clang] [clang] Reject 'auto' storage class with type specifier in C++ (PR #166004)

[Aaron Ballman via cfe-commits]

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@@ -5,14 +5,18 @@
 // The auto or register specifiers can be applied only to names of objects
 // declared in a block (6.3) or to function parameters (8.4).
 
-auto int ao; // expected-error {{illegal storage class on file-scoped variable}}
+auto int ao;
 #if __cplusplus >= 201103L // C++11 or later
-// expected-warning at -2 {{'auto' storage class specifier is not permitted in C++11, and will not be supported in future releases}}
+// expected-error at -2 {{'auto' cannot be combined with a type specifier}}
+#else
+// expected-error at -4 {{illegal storage class on file-scoped variable}}
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AaronBallman wrote:

It'd be slightly easier to review this file if we used `-verify=` and different prefixes instead of preprocessor conditionals, but I don't insist on a change for this PR either unless others have strong feelings.

https://github.com/llvm/llvm-project/pull/166004