[clang] [SSAF] Extract the virtual method override relation per TU (PR #213316)

[Balázs Benics via cfe-commits]

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@@ -0,0 +1,51 @@
+//===- VirtualMethodFamily.h ------------------------------------*- C++ -*-===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+#ifndef LLVM_CLANG_SCALABLESTATICANALYSIS_ANALYSES_VIRTUALMETHODFAMILY_VIRTUALMETHODFAMILY_H
+#define LLVM_CLANG_SCALABLESTATICANALYSIS_ANALYSES_VIRTUALMETHODFAMILY_VIRTUALMETHODFAMILY_H
+
+#include "clang/ScalableStaticAnalysis/Core/Model/EntityId.h"
+#include "clang/ScalableStaticAnalysis/Core/Model/SummaryName.h"
+#include "clang/ScalableStaticAnalysis/Core/TUSummary/EntitySummary.h"
+#include "llvm/ADT/StringRef.h"
+#include <optional>
+#include <tuple>
+#include <vector>
+
+namespace clang::ssaf {
+
+struct VirtualMethodSummary final : public EntitySummary {
+  static constexpr llvm::StringLiteral Name = "VirtualMethod";
+
+  static SummaryName summaryName() { return SummaryName(Name.str()); }
+
+  SummaryName getSummaryName() const override { return summaryName(); }
+
+  /// EntityIds of each ParmVarDecl, in source order.
+  std::vector<EntityId> ParamEntities;
+
+  /// EntityId of the synthetic return-slot entity for this method.
+  std::optional<EntityId> ReturnEntity;
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steakhal wrote:

Let's look at the `EdgeCovariantReturnOverride` test case.
There we have a covariant `clone()` method that allocates. During the reforge rewrite we would need to apply changes to that pointer declaration, right? Along with the callsites where we capture that return value.

>From how I understand, we must be able to describe the constraint that if we wanted to change the return type of a virtual method, then that must apply to all methods that possibly land in the same vtable slot (aka. this overrides, or gets overridden by).

https://github.com/llvm/llvm-project/pull/213316