[clang] [clang] Implement P3176R1: The Oxford variadic comma (PR #117524)

[via cfe-commits]

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@@ -413,6 +413,9 @@ def err_function_scope_depth_exceeded : Error<
   "function scope depth exceeded maximum of %0">, DefaultFatal;
 def err_missing_comma_before_ellipsis : Error<
   "C requires a comma prior to the ellipsis in a variadic function type">;
+def warn_deprecated_missing_comma_before_ellipsis : Warning<
+  "variadic parameters that are not preceded by a comma are deprecated">,
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cor3ntin wrote:

Maybe "declaration of a variadic function without a comma before '...' is deprecated"

("variadic parameter" is not defined and somewhat confusing)


https://github.com/llvm/llvm-project/pull/117524