[clang] [clang] Implement `__builtin_is_implicit_lifetime()` (PR #101807)

[Vlad Serebrennikov via cfe-commits]

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@@ -5637,6 +5638,27 @@ static bool EvaluateUnaryTypeTrait(Sema &Self, TypeTrait UTT,
     return false;
   case UTT_IsTriviallyEqualityComparable:
     return isTriviallyEqualityComparableType(Self, T, KeyLoc);
+  case UTT_IsImplicitLifetime: {
+    DiagnoseVLAInCXXTypeTrait(Self, TInfo,
+                              tok::kw___builtin_is_implicit_lifetime);
+    QualType UnqualT = T->getCanonicalTypeUnqualified();
+    if (UnqualT->isScalarType())
+      return true;
+    if (UnqualT->isArrayType())
+      return true;
+
+    const CXXRecordDecl *RD = UnqualT->getAsCXXRecordDecl();
+    if (!RD)
+      return false;
+    if (UnqualT->isAggregateType())
+      if (!RD->getDestructor()->isUserProvided())
+        return true;
+    if (RD->hasTrivialDestructor())
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Endilll wrote:

> but X and Y are not aggregates because they have user-declared constructors

I'm sorry, but they only thing I see there are user-declared _destructors_, not constructors.

https://github.com/llvm/llvm-project/pull/101807