[clang] [Clang] make most enums trivially equality comparable (PR #169079)

[Mariya Podchishchaeva via cfe-commits]

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@@ -503,6 +503,41 @@ static bool HasNoThrowOperator(CXXRecordDecl *RD, OverloadedOperatorKind Op,
   return false;
 }
 
+static bool equalityComparisonIsDefaulted(Sema &S, const TagDecl *Decl,
+                                          SourceLocation KeyLoc) {
+  CanQualType T = S.Context.getCanonicalTagType(Decl);
+
+  EnterExpressionEvaluationContext UnevaluatedContext(
+      S, Sema::ExpressionEvaluationContext::Unevaluated);
+  Sema::SFINAETrap SFINAE(S, /*WithAccessChecking=*/true);
+  Sema::ContextRAII TUContext(S, S.Context.getTranslationUnitDecl());
+
+  // const ClassT& obj;
+  OpaqueValueExpr Operand(KeyLoc, T.withConst(), ExprValueKind::VK_LValue);
+  UnresolvedSet<16> Functions;
+  // obj == obj;
+  S.LookupBinOp(S.TUScope, {}, BinaryOperatorKind::BO_EQ, Functions);
+
+  auto Result = S.CreateOverloadedBinOp(KeyLoc, BinaryOperatorKind::BO_EQ,
----------------
Fznamznon wrote:

Could you please spell out the type?
```suggestion
  ExprResult Result = S.CreateOverloadedBinOp(KeyLoc, BinaryOperatorKind::BO_EQ,
```

https://github.com/llvm/llvm-project/pull/169079