Remove unneeded scoped_refptr<>::get on method bind

tools/clang/base_bind_rewriters/BaseBindRewriters.cpp

+// Copyright 2016 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 file containts a clang tool to update base::Bind() callers:
+//  * Remove unneeded scoped_refptr<>::get() on method binding.
+
+#include <assert.h>
+#include <algorithm>
+#include <memory>
+#include <string>
+
+#include "clang/AST/ASTContext.h"
+#include "clang/ASTMatchers/ASTMatchers.h"
+#include "clang/ASTMatchers/ASTMatchersMacros.h"
+#include "clang/ASTMatchers/ASTMatchFinder.h"
+#include "clang/Basic/SourceManager.h"
+#include "clang/Frontend/FrontendActions.h"
+#include "clang/Lex/Lexer.h"
+#include "clang/Tooling/CommonOptionsParser.h"
+#include "clang/Tooling/Refactoring.h"
+#include "clang/Tooling/Tooling.h"
+#include "llvm/Support/CommandLine.h"
+#include "llvm/Support/TargetSelect.h"
+
+using namespace clang::ast_matchers;
+using clang::tooling::CommonOptionsParser;
+using Replacements = std::vector<clang::tooling::Replacement>;
+
+namespace {
+
+// Remove unneeded scoped_refptr<>::get on a receivers of method bind.
+// Example:
+//   // Before
+//   scoped_refptr<Foo> foo;
+//   base::Bind(&Foo::Bar, foo.get());
+//
+//   // After
+//   scoped_refptr<Foo> foo;
+//   base::Bind(&Foo::Bar, foo);
+//
+class ScopedRefptrGetRewriter : public MatchFinder::MatchCallback {
+ public:
+  explicit ScopedRefptrGetRewriter(Replacements* replacements)
+      : replacements_(replacements) {}
+
+  StatementMatcher GetMatcher() {
+    auto is_bind_call = callee(namedDecl(hasName("::base::Bind")));
+    auto is_method_bind = hasArgument(0, hasType(memberPointerType()));
+    auto is_raw_pointer_receiver = hasArgument(1, hasType(pointerType()));
+    auto is_scoped_refptr_get_call =
+        cxxMemberCallExpr(thisPointerType(namedDecl(hasName("scoped_refptr"))),
+                          callee(namedDecl(hasName("get"))));
+    return callExpr(is_bind_call, is_method_bind, is_raw_pointer_receiver,
+                    hasArgument(1, is_scoped_refptr_get_call),
+                    hasArgument(1, stmt().bind("target")));
+  }
+
+  void run(const MatchFinder::MatchResult& result) override {
+    auto* target = result.Nodes.getNodeAs<clang::CXXMemberCallExpr>("target");
+    assert(target && "Unexpected match! No Expr captured!");
+
+    clang::CharSourceRange range = clang::CharSourceRange::getTokenRange(
+        result.SourceManager->getSpellingLoc(target->getLocStart()),
+        result.SourceManager->getSpellingLoc(target->getLocEnd()));
+
+    auto* member = llvm::dyn_cast<clang::MemberExpr>(target->getCallee());

[dcheng, 2016/08/31 06:14:44]

Nit: use cast<> here, since we want to assert if this fails for some reason (and
we'll crash anyway when we try to deref it)

[tzik, 2016/08/31 09:06:43]

Done.

+    clang::CharSourceRange member_range = clang::CharSourceRange::getTokenRange(

[dcheng, 2016/08/31 06:14:44]

To clarify, I would do this:

auto range = clang::CharSourceRange::getTokenRange(
  result.SourceManager->getSpellingLoc(member->getOperatorLoc()),
  result.SourceManager->getSpellingLoc(target->getLocEnd()));

replacements_->emplace_back(
  *results.SourceManager, range, "");

That way, we don't need to call getSourceText() at all and account for any
weirdness.

[tzik, 2016/08/31 09:06:43]

Oh... Thanks! Updated.

TIL:
 - SourceLocation points a token instead of a character location.
 - CharSourceRange is an inclusive range.
http://clang.llvm.org/docs/InternalsManual.html#the-sourcelocation-and-source...

+        result.SourceManager->getSpellingLoc(member->getLocStart()),
+        result.SourceManager->getSpellingLoc(member->getOperatorLoc()));
+    std::string text = clang::Lexer::getSourceText(
+        member_range, *result.SourceManager, result.Context->getLangOpts());
+    if (member->isArrow())
+      text.erase(text.size() - 2);
+    else
+      text.erase(text.size() - 1);
+    replacements_->emplace_back(
+        *result.SourceManager, range, text);
+  }
+
+ private:
+  Replacements* replacements_;
+};
+
+llvm::cl::extrahelp common_help(CommonOptionsParser::HelpMessage);
+
+}  // namespace.
+
+int main(int argc, const char* argv[]) {
+  llvm::InitializeNativeTarget();
+  llvm::InitializeNativeTargetAsmParser();
+  llvm::cl::OptionCategory category(
+      "Remove raw pointer on the receiver of Bind() target");
+  CommonOptionsParser options(argc, argv, category);
+  clang::tooling::ClangTool tool(options.getCompilations(),
+                                 options.getSourcePathList());
+
+  MatchFinder match_finder;
+  std::vector<clang::tooling::Replacement> replacements;
+
+
+  ScopedRefptrGetRewriter scoped_refptr_rewriter(&replacements);
+  match_finder.addMatcher(scoped_refptr_rewriter.GetMatcher(),
+                          &scoped_refptr_rewriter);
+
+  std::unique_ptr<clang::tooling::FrontendActionFactory> factory =
+      clang::tooling::newFrontendActionFactory(&match_finder);
+  int result = tool.run(factory.get());
+  if (result != 0)
+    return result;
+
+  // Serialization format is documented in tools/clang/scripts/run_tool.py
+  llvm::outs() << "==== BEGIN EDITS ====\n";
+  for (const auto& r : replacements) {
+    std::string replacement_text = r.getReplacementText().str();
+    std::replace(replacement_text.begin(), replacement_text.end(), '\n', '\0');
+    llvm::outs() << "r:::" << r.getFilePath() << ":::" << r.getOffset()
+                 << ":::" << r.getLength() << ":::" << replacement_text << "\n";
+  }
+  llvm::outs() << "==== END EDITS ====\n";
+
+  return 0;
+}