[clang] [llvm] Enable fexec-charset option (PR #138895)

[Sergei Barannikov via cfe-commits]

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@@ -126,6 +126,17 @@ static bool IsEscapeValidInUnevaluatedStringLiteral(char Escape) {
   return false;
 }
 
+static llvm::ErrorOr<char>
+convertCharacter(StringRef Char, llvm::TextEncodingConverter *Converter) {
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s-barannikov wrote:

If `Converter` can't be nullptr, it should be passed by (const) reference

https://github.com/llvm/llvm-project/pull/138895