[clang] [llvm] [Sema] Implement support for -Wformat-signedness (PR #74440)

[Takuya Shimizu via cfe-commits]

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@@ -918,6 +918,9 @@ def Wdeprecated : Flag<["-"], "Wdeprecated">, Group<W_Group>,
   HelpText<"Enable warnings for deprecated constructs and define __DEPRECATED">;
 def Wno_deprecated : Flag<["-"], "Wno-deprecated">, Group<W_Group>,
   Visibility<[ClangOption, CC1Option]>;
+def Wformat_signedness : Flag<["-"], "Wformat-signedness">,
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hazohelet wrote:

I think the warning option config should go to `clang/include/clang/Basic/DiagnosticSemaKinds.td` instead of the toplevel driver setting. For example,  you wouldn't have `-Wno-format-signedness` atm.

https://github.com/llvm/llvm-project/pull/74440