[clang] [clang] Report Diagnostic when builtin vector has negative size (PR #166055)

[Amr Hesham via cfe-commits]

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@@ -786,3 +786,8 @@ const long long e = *0; // expected-error {{indirection requires pointer operand
 double f = a - e;       // expected-error {{cannot initialize a variable of type 'double' with an rvalue of type '__attribute__((__vector_size__(1 * sizeof(double)))) double' (vector of 1 'double' value)}}
 int h = c - e;          // expected-error {{cannot initialize a variable of type 'int' with an rvalue of type '__attribute__((__vector_size__(1 * sizeof(long)))) long' (vector of 1 'long' value)}}
 }
+
+typedef int v_neg_size __attribute__((vector_size(-8))); // expected-error{{vector must have non-negative size}}
+typedef int v_neg_size_2 __attribute__((vector_size(-1 * 8))); // expected-error{{vector must have non-negative size}}
+typedef int v_ext_neg_size __attribute__((ext_vector_type(-8))); // expected-error{{vector must have non-negative size}}
+typedef int v_ext_neg_size2 __attribute__((ext_vector_type(-1 * 8))); // expected-error{{vector must have non-negative size}}
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AmrDeveloper wrote:

Yes, it works. I just need to write this test in another file that allows C++11 extension to be able to use `using`

https://github.com/llvm/llvm-project/pull/166055