[clang] [Clang] Add diagnostic when scoped enumeration requires an explicit conversion for binary operations (PR #152698)

[Erich Keane via cfe-commits]

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@@ -10742,9 +10742,53 @@ static void DiagnoseBadDivideOrRemainderValues(Sema& S, ExprResult &LHS,
                             << IsDiv << RHS.get()->getSourceRange());
 }
 
+static void diagnoseScopedEnums(Sema &S, const SourceLocation Loc,
+                                const ExprResult &LHS, const ExprResult &RHS,
+                                BinaryOperatorKind Opc) {
+  const Expr *LHSExpr = LHS.get();
+  const Expr *RHSExpr = RHS.get();
+  if (!LHSExpr || !RHSExpr)
+    return;
+  const QualType LHSType = LHSExpr->getType();
+  const QualType RHSType = RHSExpr->getType();
+  const bool LHSIsScoped = LHSType->isScopedEnumeralType();
+  const bool RHSIsScoped = RHSType->isScopedEnumeralType();
+  if (!LHSIsScoped && !RHSIsScoped)
+    return;
+  if (!LHSIsScoped && !LHSType->isIntegralOrUnscopedEnumerationType())
+    return;
+  if (!RHSIsScoped && !RHSType->isIntegralOrUnscopedEnumerationType())
+    return;
+  if (BinaryOperator::isAssignmentOp(Opc) && LHSIsScoped)
+    return;
+  bool isCxx23 = S.getLangOpts().CPlusPlus23;
+  unsigned diagID =
+      isCxx23 ? diag::note_no_implicit_conversion_for_scoped_enum_cxx23
+              : diag::note_no_implicit_conversion_for_scoped_enum;
+  auto diagnosticHelper = [&S, isCxx23, diagID](const Expr *expr, const QualType type) {
+    SourceLocation beginLoc = expr->getBeginLoc();
+    QualType intType =
+        type->castAs<EnumType>()->getDecl()->getIntegerType();
+    std::string insertionString =
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erichkeane wrote:

You seem to have switched capitalization mid-patch :)  Variable name start with a capital letter: https://llvm.org/docs/CodingStandards.html#name-types-functions-variables-and-enumerators-properly

https://github.com/llvm/llvm-project/pull/152698