Fix bitrot in Chrome clang tool infrastructure.

tools/clang/rewrite_scoped_ptr_ctor_null/RewriteScopedPtrCtorNull.cpp

-// Copyright (c) 2013 The Chromium Authors. All rights reserved.
-// Use of this source code is governed by a BSD-style license that can be
-// found in the LICENSE file.
-//
-// This implements a Clang tool to convert all instances of std::string("") to
-// std::string(). The latter is more efficient (as std::string doesn't have to
-// take a copy of an empty string) and generates fewer instructions as well. It
-// should be run using the tools/clang/scripts/run_tool.py helper.
-
-#include "clang/ASTMatchers/ASTMatchers.h"
-#include "clang/ASTMatchers/ASTMatchFinder.h"
-#include "clang/Basic/SourceManager.h"
-#include "clang/Frontend/FrontendActions.h"
-#include "clang/Tooling/CommonOptionsParser.h"
-#include "clang/Tooling/Refactoring.h"
-#include "clang/Tooling/Tooling.h"
-#include "llvm/Support/CommandLine.h"
-
-using clang::ast_matchers::MatchFinder;
-using clang::ast_matchers::argumentCountIs;
-using clang::ast_matchers::bindTemporaryExpr;
-using clang::ast_matchers::constructorDecl;
-using clang::ast_matchers::constructExpr;
-using clang::ast_matchers::defaultArgExpr;
-using clang::ast_matchers::expr;
-using clang::ast_matchers::forEach;
-using clang::ast_matchers::has;
-using clang::ast_matchers::hasArgument;
-using clang::ast_matchers::hasDeclaration;
-using clang::ast_matchers::matchesName;
-using clang::ast_matchers::id;
-using clang::ast_matchers::methodDecl;
-using clang::ast_matchers::newExpr;
-using clang::ast_matchers::ofClass;
-using clang::ast_matchers::unless;
-using clang::ast_matchers::varDecl;
-using clang::tooling::CommonOptionsParser;
-using clang::tooling::Replacement;
-using clang::tooling::Replacements;
-
-namespace {
-
-bool IsNullConstant(const clang::Expr& expr, clang::ASTContext* context) {
-  return expr.isNullPointerConstant(*context,
-                                    clang::Expr::NPC_ValueDependentIsNotNull) !=
-         clang::Expr::NPCK_NotNull;
-}
-
-// Handles replacements for stack and heap-allocated instances, e.g.:
-// scoped_ptr<T> a(NULL);
-// scoped_ptr<T>* b = new scoped_ptr<T>(NULL);
-// ...though the latter should be pretty rare.
-class ConstructorCallback : public MatchFinder::MatchCallback {
- public:
-  ConstructorCallback(Replacements* replacements)
-      : replacements_(replacements) {}
-
-  virtual void run(const MatchFinder::MatchResult& result) LLVM_OVERRIDE;
-
- private:
-  Replacements* const replacements_;
-};
-
-// Handles replacements for invocations of scoped_ptr<T>(NULL) in an initializer
-// list.
-class InitializerCallback : public MatchFinder::MatchCallback {
- public:
-  InitializerCallback(Replacements* replacements)
-      : replacements_(replacements) {}
-
-  virtual void run(const MatchFinder::MatchResult& result) LLVM_OVERRIDE;
-
- private:
-  Replacements* const replacements_;
-};
-
-// Handles replacements for invocations of scoped_ptr<T>(NULL) in a temporary
-// context, e.g. return scoped_ptr<T>(NULL).
-class TemporaryCallback : public MatchFinder::MatchCallback {
- public:
-  TemporaryCallback(Replacements* replacements) : replacements_(replacements) {}
-
-  virtual void run(const MatchFinder::MatchResult& result) LLVM_OVERRIDE;
-
- private:
-  Replacements* const replacements_;
-};
-
-class EmptyStringConverter {
- public:
-  explicit EmptyStringConverter(Replacements* replacements)
-      : constructor_callback_(replacements),
-        initializer_callback_(replacements),
-        temporary_callback_(replacements) {}
-
-  void SetupMatchers(MatchFinder* match_finder);
-
- private:
-  ConstructorCallback constructor_callback_;
-  InitializerCallback initializer_callback_;
-  TemporaryCallback temporary_callback_;
-};
-
-void EmptyStringConverter::SetupMatchers(MatchFinder* match_finder) {
-  const char kPattern[] = "^::(scoped_ptr|scoped_ptr_malloc)$";
-  const clang::ast_matchers::StatementMatcher& constructor_call = id(
-      "call",
-      constructExpr(hasDeclaration(methodDecl(ofClass(matchesName(kPattern)))),
-                    argumentCountIs(1),
-                    hasArgument(0, id("arg", expr())),
-                    unless(hasArgument(0, defaultArgExpr()))));
-
-  match_finder->addMatcher(varDecl(forEach(constructor_call)),
-                           &constructor_callback_);
-  match_finder->addMatcher(newExpr(has(constructor_call)),
-                           &constructor_callback_);
-  match_finder->addMatcher(bindTemporaryExpr(has(constructor_call)),
-                           &temporary_callback_);
-  match_finder->addMatcher(constructorDecl(forEach(constructor_call)),
-                           &initializer_callback_);
-}
-
-void ConstructorCallback::run(const MatchFinder::MatchResult& result) {
-  const clang::Expr* arg = result.Nodes.getNodeAs<clang::Expr>("arg");
-  if (!IsNullConstant(*arg, result.Context))
-    return;
-
-  const clang::CXXConstructExpr* call =
-      result.Nodes.getNodeAs<clang::CXXConstructExpr>("call");
-  clang::CharSourceRange range =
-      clang::CharSourceRange::getTokenRange(call->getParenRange());
-  replacements_->insert(Replacement(*result.SourceManager, range, ""));
-}
-
-void InitializerCallback::run(const MatchFinder::MatchResult& result) {
-  const clang::Expr* arg = result.Nodes.getNodeAs<clang::Expr>("arg");
-  if (!IsNullConstant(*arg, result.Context))
-    return;
-
-  const clang::CXXConstructExpr* call =
-      result.Nodes.getNodeAs<clang::CXXConstructExpr>("call");
-  replacements_->insert(Replacement(*result.SourceManager, call, ""));
-}
-
-void TemporaryCallback::run(const MatchFinder::MatchResult& result) {
-  const clang::Expr* arg = result.Nodes.getNodeAs<clang::Expr>("arg");
-  if (!IsNullConstant(*arg, result.Context))
-    return;
-
-  // TODO(dcheng): File a bug with clang. There should be an easier way to do
-  // this replacement, but getTokenRange(call->getParenRange()) and the obvious
-  // (but incorrect) arg both don't work. The former is presumably just buggy,
-  // while the latter probably has to do with the fact that NULL is actually a
-  // macro which expands to a built-in.
-  clang::SourceRange range = arg->getSourceRange();
-  clang::SourceRange expansion_range(
-      result.SourceManager->getExpansionLoc(range.getBegin()),
-      result.SourceManager->getExpansionLoc(range.getEnd()));
-  replacements_->insert(
-      Replacement(*result.SourceManager,
-                  clang::CharSourceRange::getTokenRange(expansion_range),
-                  ""));
-}
-
-}  // namespace
-
-static llvm::cl::extrahelp common_help(CommonOptionsParser::HelpMessage);
-
-int main(int argc, const char* argv[]) {
-  CommonOptionsParser options(argc, argv);
-  clang::tooling::ClangTool tool(options.getCompilations(),
-                                 options.getSourcePathList());
-
-  Replacements replacements;
-  EmptyStringConverter converter(&replacements);
-  MatchFinder match_finder;
-  converter.SetupMatchers(&match_finder);
-
-  int result =
-      tool.run(clang::tooling::newFrontendActionFactory(&match_finder));
-  if (result != 0)
-    return result;
-
-  // Each replacement line should have the following format:
-  // r:<file path>:<offset>:<length>:<replacement text>
-  // Only the <replacement text> field can contain embedded ":" characters.
-  // TODO(dcheng): Use a more clever serialization.
-  llvm::outs() << "==== BEGIN EDITS ====\n";
-  for (Replacements::const_iterator it = replacements.begin();
-       it != replacements.end();
-       ++it) {
-    llvm::outs() << "r:" << it->getFilePath() << ":" << it->getOffset() << ":"
-                 << it->getLength() << ":" << it->getReplacementText() << "\n";
-  }
-  llvm::outs() << "==== END EDITS ====\n";
-
-  return 0;
-}