[clang] [Clang] Implement P2747 constexpr placement new (PR #104586)

[Vlad Serebrennikov via cfe-commits]

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@@ -10030,22 +10021,32 @@ bool PointerExprEvaluator::VisitCXXNewExpr(const CXXNewExpr *E) {
     // (which should presumably be valid only if N is a multiple of
     // alignof(int), and in any case can't be deallocated unless N is
     // alignof(X) and X has new-extended alignment).
-    if (E->getNumPlacementArgs() != 1 ||
-        !E->getPlacementArg(0)->getType()->isNothrowT())
-      return Error(E, diag::note_constexpr_new_placement);
-
     LValue Nothrow;
     if (!EvaluateLValue(E->getPlacementArg(0), Nothrow, Info))
       return false;
     IsNothrow = true;
+  } else if (OperatorNew->isReservedGlobalPlacementOperator()) {
+    if (!EvaluatePointer(E->getPlacementArg(0), Result, Info))
+      return false;
+    if (Result.Designator.Invalid)
+      return false;
+    /// if(!lifetimeStartedInEvaluation(Info, Result.getLValueBase()))
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Endilll wrote:

Debugging leftovers?

https://github.com/llvm/llvm-project/pull/104586