[clang-tools-extra] [clangd] Add tweak to add pure virtual overrides (PR #139348)

[Marco Maia via cfe-commits]

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@@ -0,0 +1,349 @@
+//===--- AddPureVirtualOverride.cpp ------------------------------*- 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
+//
+//===----------------------------------------------------------------------===//
+
+#include "refactor/Tweak.h"
+
+#include "clang/AST/ASTContext.h"
+#include "clang/AST/DeclCXX.h"
+#include "clang/AST/Type.h"
+#include "clang/AST/TypeLoc.h"
+#include "clang/Basic/LLVM.h"
+#include "clang/Basic/SourceLocation.h"
+#include "clang/Tooling/Core/Replacement.h"
+#include "llvm/ADT/DenseSet.h"
+#include "llvm/Support/FormatVariadic.h"
+#include <algorithm>
+#include <functional>
+#include <map>
+#include <set>
+#include <string>
+#include <vector>
+
+namespace clang {
+namespace clangd {
+namespace {
+
+class OverridePureVirtuals : public Tweak {
+public:
+  const char *id() const final; // defined by REGISTER_TWEAK.
+  bool prepare(const Selection &Sel) override;
+  Expected<Effect> apply(const Selection &Sel) override;
+  std::string title() const override { return "Override pure virtual methods"; }
+  llvm::StringLiteral kind() const override {
+    return CodeAction::REFACTOR_KIND;
+  }
+
+private:
+  // Stores the CXXRecordDecl of the class being modified.
+  const CXXRecordDecl *CurrentDecl = nullptr;
+  // Stores pure virtual methods that need overriding, grouped by their original
+  // access specifier.
+  std::map<AccessSpecifier, std::vector<const CXXMethodDecl *>>
+      MissingMethodsByAccess;
+  // Stores the source locations of existing access specifiers in CurrentDecl.
+  std::map<AccessSpecifier, SourceLocation> AccessSpecifierLocations;
+
+  // Helper function to gather information before applying the tweak.
+  void collectMissingPureVirtuals(const Selection &Sel);
+};
+
+REGISTER_TWEAK(OverridePureVirtuals)
+
+// Collects all unique, canonical pure virtual methods from a class and its
+// entire inheritance hierarchy. This function aims to find methods that *could*
+// make a derived class abstract if not implemented.
+std::vector<const CXXMethodDecl *>
+getAllUniquePureVirtualsFromHierarchy(const CXXRecordDecl *Decl) {
+  std::vector<const CXXMethodDecl *> Result;
+  llvm::DenseSet<const CXXMethodDecl *> VisitedCanonicalMethods;
+  // We declare it as a std::function because we are going to call it
+  // recursively.
+  std::function<void(const CXXRecordDecl *)> Collect;
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marcogmaia wrote:

Replaced it with a free function.

https://github.com/llvm/llvm-project/pull/139348