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

[Aaron Ballman via cfe-commits]

================
@@ -12465,6 +12465,20 @@ isArithmeticArgumentPromotion(Sema &S, const ImplicitCastExpr *ICE) {
          S.Context.getFloatingTypeOrder(From, To) < 0;
 }
 
+static analyze_format_string::ArgType::MatchKind
+handleFormatSignedness(analyze_format_string::ArgType::MatchKind Match,
+                       DiagnosticsEngine &Diags, SourceLocation Loc) {
+  if (Match == analyze_format_string::ArgType::NoMatchSignedness) {
+    if (!Diags.isIgnored(
+            diag::warn_format_conversion_argument_type_mismatch_signedness,
+            Loc))
+      Match = analyze_format_string::ArgType::NoMatch;
+    else
+      Match = analyze_format_string::ArgType::Match;
----------------
AaronBallman wrote:

```suggestion
   Match = Diags.isIgnored(
            diag::warn_format_conversion_argument_type_mismatch_signedness,
            Loc) ? analyze_format_string::ArgType::Match : analyze_format_string::ArgType::NoMatch;
```
Probably need to be reformatted, but makes the code a little bit more clear (IMO).

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