[clang] Add unique_ptr <T[]> accesses to -Wunsafe-buffer-usage (PR #156773)

[via cfe-commits]

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@@ -1318,6 +1319,105 @@ static bool isSupportedVariable(const DeclRefExpr &Node) {
   return D != nullptr && isa<VarDecl>(D);
 }
 
+static bool isUniquePtrArray(const CXXRecordDecl *RecordDecl) {
+  if (!RecordDecl || !RecordDecl->isInStdNamespace() ||
+      RecordDecl->getNameAsString() != "unique_ptr") {
+    return false;
+  }
+
+  const ClassTemplateSpecializationDecl *class_template_specialization_decl =
+      dyn_cast<ClassTemplateSpecializationDecl>(RecordDecl);
+  if (!class_template_specialization_decl) {
+    return false;
+  }
+
+  const TemplateArgumentList &template_args =
+      class_template_specialization_decl->getTemplateArgs();
+
+  if (template_args.size() == 0) {
+    return false;
+  }
+
+  const TemplateArgument &first_arg = template_args[0];
+
+  if (first_arg.getKind() != TemplateArgument::Type) {
+    return false;
+  }
+
+  QualType referred_type = first_arg.getAsType();
+
+  if (referred_type->isArrayType()) {
+    return true;
+  }
+
+  return false;
+}
+
+class UniquePtrArrayAccessGadget : public WarningGadget {
+  static constexpr const char *const AccessorTag = "unique_ptr_array_access";
+  const CXXOperatorCallExpr *TheAccessorExpr;
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shreya-jain wrote:

I've seen this convention in other files in llvm, but within this file I don't see it, so I changed it to AccessorExpr.

https://github.com/llvm/llvm-project/pull/156773