[clang] [Sema] Instantiate destructors for initialized members (PR #128866)

[Erich Keane via cfe-commits]

================
@@ -5283,6 +5283,102 @@ Sema::SetDelegatingInitializer(CXXConstructorDecl *Constructor,
   return false;
 }
 
+static CXXDestructorDecl *LookupDestructorIfRelevant(Sema &S,
+                                                     CXXRecordDecl *Class) {
+  if (Class->isInvalidDecl())
+    return nullptr;
+  if (Class->hasIrrelevantDestructor())
+    return nullptr;
+
+  // Dtor might still be missing, e.g because it's invalid.
+  return S.LookupDestructor(Class);
+}
+
+static void MarkFieldDestructorReferenced(Sema &S, SourceLocation Location,
+                                          FieldDecl *Field) {
+  if (Field->isInvalidDecl())
+    return;
+
+  // Don't destroy incomplete or zero-length arrays.
+  if (isIncompleteOrZeroLengthArrayType(S.Context, Field->getType()))
+    return;
+
+  QualType FieldType = S.Context.getBaseElementType(Field->getType());
+
+  auto *FieldClassDecl = FieldType->getAsCXXRecordDecl();
+  if (!FieldClassDecl)
+    return;
+
+  // The destructor for an implicit anonymous union member is never invoked.
+  if (FieldClassDecl->isUnion() && FieldClassDecl->isAnonymousStructOrUnion())
+    return;
+
+  auto *Dtor = LookupDestructorIfRelevant(S, FieldClassDecl);
+  if (!Dtor)
+    return;
+
+  S.CheckDestructorAccess(Field->getLocation(), Dtor,
+                          S.PDiag(diag::err_access_dtor_field)
+                              << Field->getDeclName() << FieldType);
+
+  S.MarkFunctionReferenced(Location, Dtor);
+  S.DiagnoseUseOfDecl(Dtor, Location);
+}
+
+static void MarkBaseDestructorsReferenced(Sema &S, SourceLocation Location,
+                                          CXXRecordDecl *ClassDecl) {
+  if (ClassDecl->isDependentContext())
+    return;
+
+  // We only potentially invoke the destructors of potentially constructed
+  // subobjects.
+  bool VisitVirtualBases = !ClassDecl->isAbstract();
+
+  // If the destructor exists and has already been marked used in the MS ABI,
+  // then virtual base destructors have already been checked and marked used.
+  // Skip checking them again to avoid duplicate diagnostics.
+  if (S.Context.getTargetInfo().getCXXABI().isMicrosoft()) {
+    CXXDestructorDecl *Dtor = ClassDecl->getDestructor();
+    if (Dtor && Dtor->isUsed())
+      VisitVirtualBases = false;
+  }
+
+  llvm::SmallPtrSet<const CXXRecordDecl *, 8> DirectVirtualBases;
+
+  // Bases.
+  for (const auto &Base : ClassDecl->bases()) {
+    const auto *RT = Base.getType()->getAs<RecordType>();
+    if (!RT)
+      continue;
+
+    auto *BaseClassDecl = cast<CXXRecordDecl>(RT->getDecl());
----------------
erichkeane wrote:

```suggestion
    auto *BaseClassDecl = Base.getType()->getAsCXXRecordDecl();```

https://github.com/llvm/llvm-project/pull/128866