fix build

Author: cor3ntin

clang/lib/Sema/SemaExpr.cpp

@@ -1518,7 +1518,7 @@ static void checkEnumArithmeticConversions(Sema &S, Expr *LHS, Expr *RHS,
     unsigned DiagID;
     // In C++ 26, usual arithmetic conversions between 2 different enum types
     // are ill-formed.
-    if (getLangOpts().CPlusPlus26)
+    if (S.getLangOpts().CPlusPlus26)
       DiagID = diag::warn_conv_mixed_enum_types_cxx26;
     else if (!L->castAs<EnumType>()->getDecl()->hasNameForLinkage() ||
              !R->castAs<EnumType>()->getDecl()->hasNameForLinkage()) {