[clang] [Clang][RFC] Introduce a trait to determine the structure binding size (PR #131515)

[Erich Keane via cfe-commits]

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@@ -1854,47 +1854,34 @@ bool MaterializeTemporaryExpr::isUsableInConstantExpressions(
 
 TypeTraitExpr::TypeTraitExpr(QualType T, SourceLocation Loc, TypeTrait Kind,
                              ArrayRef<TypeSourceInfo *> Args,
-                             SourceLocation RParenLoc, bool Value)
+                             SourceLocation RParenLoc,
+                             std::variant<bool, APValue> Value)
     : Expr(TypeTraitExprClass, T, VK_PRValue, OK_Ordinary), Loc(Loc),
       RParenLoc(RParenLoc) {
   assert(Kind <= TT_Last && "invalid enum value!");
+
   TypeTraitExprBits.Kind = Kind;
   assert(static_cast<unsigned>(Kind) == TypeTraitExprBits.Kind &&
          "TypeTraitExprBits.Kind overflow!");
-  TypeTraitExprBits.IsBooleanTypeTrait = true;
-  TypeTraitExprBits.Value = Value;
-  TypeTraitExprBits.NumArgs = Args.size();
-  assert(Args.size() == TypeTraitExprBits.NumArgs &&
-         "TypeTraitExprBits.NumArgs overflow!");
 
-  auto **ToArgs = getTrailingObjects<TypeSourceInfo *>();
-  for (unsigned I = 0, N = Args.size(); I != N; ++I)
-    ToArgs[I] = Args[I];
-
-  setDependence(computeDependence(this));
-}
+  TypeTraitExprBits.IsBooleanTypeTrait = Value.index() == 0;
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erichkeane wrote:

minor preference for `holds_alternative`.

https://github.com/llvm/llvm-project/pull/131515