[clang] [llvm][Stmt]:Fix musttail attribute on a function with not_tail_called attribute has no warning/error (PR #134465)

[Aaron Ballman via cfe-commits]

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@@ -3134,6 +3134,9 @@ def warn_function_attribute_ignored_in_stmt : Warning<
   "use '%0' on statements">,
   InGroup<IgnoredAttributes>;
 
+def err_musttail_conflicts_with_not_tail_called : Error<
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AaronBallman wrote:

Can we reuse `err_musttail_mismatch` instead?

https://github.com/llvm/llvm-project/pull/134465