[clang] [clang] Remove diagnostic that came with `[[clang::preferred_type]]` (PR #70632)

[via cfe-commits]

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@@ -5928,28 +5928,6 @@ static void handlePreferredTypeAttr(Sema &S, Decl *D, const ParsedAttr &AL) {
   S.RequireCompleteType(ParmTSI->getTypeLoc().getBeginLoc(), QT,
                         diag::err_incomplete_type);
 
-  if (QT->isEnumeralType()) {
-    auto IsCorrespondingType = [&](QualType LHS, QualType RHS) {
-      assert(LHS != RHS);
-      if (LHS->isSignedIntegerType())
-        return LHS == S.getASTContext().getCorrespondingSignedType(RHS);
-      return LHS == S.getASTContext().getCorrespondingUnsignedType(RHS);
-    };
-    QualType BitfieldType =
-        cast<FieldDecl>(D)->getType()->getCanonicalTypeUnqualified();
-    QualType EnumUnderlyingType = QT->getAs<EnumType>()
-                                      ->getDecl()
-                                      ->getIntegerType()
-                                      ->getCanonicalTypeUnqualified();
-    if (EnumUnderlyingType != BitfieldType &&
-        !IsCorrespondingType(EnumUnderlyingType, BitfieldType)) {
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cor3ntin wrote:

I think we should keep the diagnostics, but only emit it when the type of the enum  has a sizeof that is greater than the type of the bitfields.

Another solution would be to compare the number of bits of the greater enumerator with the number of bits in the bitfield.

https://github.com/llvm/llvm-project/pull/70632