[clang] [llvm] Implement resource binding type prefix mismatch errors (PR #87578)

[Joshua Batista via cfe-commits]

================
@@ -44,7 +44,7 @@ void foo2() {
   // expected-warning at +1 {{'register' attribute only applies to cbuffer/tbuffer and external global variables}}
   extern RWBuffer<float> U2 : register(u5);
 }
-// FIXME: expect-error once fix https://github.com/llvm/llvm-project/issues/57886.
+// expected-error at +1 {{invalid register name prefix 'u' for 'float' (expected 't')}}
----------------
bob80905 wrote:

According to @tex3d 's comment, the ` expected 'b', 'c', or 'i' binding` is no longer supported, so I don't think I should weave that into this implementation. I did ask what we should expect the prefix to be, but I haven't received an answer yet. Sounds to me like you think it should be 'b', because it's a constant inside a CBuffer?

https://github.com/llvm/llvm-project/pull/87578