shuaiwang created this revision.
Herald added subscribers: cfe-commits, xazax.hun, mgorny, klimek.
shuaiwang added a reviewer: sbenza.

Repository:
  rCTE Clang Tools Extra

https://reviews.llvm.org/D45702

Files:
  clang-tidy/readability/CMakeLists.txt
  clang-tidy/readability/ReadabilityTidyModule.cpp
  clang-tidy/readability/RedundantDataCallCheck.cpp
  clang-tidy/readability/RedundantDataCallCheck.h
  docs/ReleaseNotes.rst
  docs/clang-tidy/checks/list.rst
  docs/clang-tidy/checks/readability-redundant-data-call.rst
  test/clang-tidy/readability-redundant-data-call.cpp

Index: test/clang-tidy/readability-redundant-data-call.cpp
===================================================================
--- /dev/null
+++ test/clang-tidy/readability-redundant-data-call.cpp
@@ -0,0 +1,108 @@
+// RUN: %check_clang_tidy %s readability-redundant-data-call %t \
+// RUN: -config="{CheckOptions: \
+// RUN: [{key: readability-redundant-data-call.Types, \
+// RUN:   value: '::std::basic_string;::std::basic_string_view;MyVector'}]}" --
+
+namespace std {
+
+template <class T>
+class basic_string {
+ public:
+   using size_type = unsigned;
+   using value_type = T;
+   using reference = value_type&;
+   using const_reference = const value_type&;
+
+   reference operator[](size_type);
+   const_reference operator[](size_type) const;
+   T* data();
+   const T* data() const;
+};
+
+using string = basic_string<char>;
+
+template <class T>
+class basic_string_view {
+ public:
+  using size_type = unsigned;
+  using const_reference = const T&;
+  using const_pointer = const T*;
+
+  constexpr const_reference operator[](size_type) const;
+  constexpr const_pointer data() const noexcept;
+};
+
+using string_view = basic_string_view<char>;
+
+}
+
+template <class T>
+class MyVector {
+ public:
+  using size_type = unsigned;
+  using const_reference = const T&;
+  using const_pointer = const T*;
+
+  const_reference operator[](size_type) const;
+  const T* data() const noexcept;
+};
+
+#define DO(x) do { x; } while (false)
+#define ACCESS(x) (x)
+#define GET(x, i) (x).data()[i]
+
+template <class T>
+class Foo {
+ public:
+  char bar(int i) {
+    return x.data()[i];
+  }
+ private:
+  T x;
+};
+
+void f(int i) {
+  MyVector<int> v;
+  int x = v.data()[i];
+  // CHECK-MESSAGES: :[[@LINE-1]]:13: warning: redundant call to .data() [readability-redundant-data-call]
+  // CHECK-FIXES: int x = v[i];
+
+  std::string s;
+  char c1 = s.data()[i];
+  // CHECK-MESSAGES: :[[@LINE-1]]:15: warning: redundant call to .data()
+  // CHECK-FIXES: char c1 = s[i];
+
+  std::string_view sv;
+  char c2 = sv.data()[i];
+  // CHECK-MESSAGES: :[[@LINE-1]]:16: warning: redundant call to .data()
+  // CHECK-FIXES: char c2 = sv[i];
+
+  std::string* ps = &s;
+  char c3 = ps->data()[i];
+  // CHECK-MESSAGES: :[[@LINE-1]]:17: warning: redundant call to .data()
+  // CHECK-FIXES: char c3 = (*ps)[i];
+
+  char c4 = (*ps).data()[i];
+  // CHECK-MESSAGES: :[[@LINE-1]]:19: warning: redundant call to .data()
+  // CHECK-FIXES: char c4 = (*ps)[i];
+
+  DO(char c5 = s.data()[i]);
+  // CHECK-MESSAGES: :[[@LINE-1]]:18: warning: redundant call to .data()
+  // CHECK-FIXES: DO(char c5 = s[i]);
+
+  char c6 = ACCESS(s).data()[i];
+  // CHECK-MESSAGES: :[[@LINE-1]]:23: warning: redundant call to .data()
+  // CHECK-FIXES: char c6 = ACCESS(s)[i];
+
+  char c7 = ACCESS(s.data())[i];
+  // CHECK-MESSAGES: :[[@LINE-1]]:22: warning: redundant call to .data()
+  // CHECK-FIXES: char c7 = ACCESS(s)[i];
+
+  char c8 = ACCESS(s.data()[i]);
+  // CHECK-MESSAGES: :[[@LINE-1]]:22: warning: redundant call to .data()
+  // CHECK-FIXES: char c8 = ACCESS(s[i]);
+
+  char c9 = GET(s, i);
+
+  char c10 = Foo<std::string>{}.bar(i);
+}
Index: docs/clang-tidy/checks/readability-redundant-data-call.rst
===================================================================
--- /dev/null
+++ docs/clang-tidy/checks/readability-redundant-data-call.rst
@@ -0,0 +1,14 @@
+.. title:: clang-tidy - readability-redundant-data-call
+
+readability-redundant-data-call
+===============================
+
+This check suggests removing redundant `.data()` calls.
+
+Examples:
+
+.. code-block:: c++
+  std::string s = ...;
+  char c = s.data()[i];  // char c = s[i];
+
+The type(s) that triggers this check can be configured with `Types` option.
Index: docs/clang-tidy/checks/list.rst
===================================================================
--- docs/clang-tidy/checks/list.rst
+++ docs/clang-tidy/checks/list.rst
@@ -91,8 +91,8 @@
    cppcoreguidelines-pro-type-vararg
    cppcoreguidelines-slicing
    cppcoreguidelines-special-member-functions
-   fuchsia-header-anon-namespaces (redirects to google-build-namespaces) <fuchsia-header-anon-namespaces>
    fuchsia-default-arguments
+   fuchsia-header-anon-namespaces (redirects to google-build-namespaces) <fuchsia-header-anon-namespaces>
    fuchsia-multiple-inheritance
    fuchsia-overloaded-operator
    fuchsia-statically-constructed-objects
@@ -218,6 +218,7 @@
    readability-named-parameter
    readability-non-const-parameter
    readability-redundant-control-flow
+   readability-redundant-data-call
    readability-redundant-declaration
    readability-redundant-function-ptr-dereference
    readability-redundant-member-init
Index: docs/ReleaseNotes.rst
===================================================================
--- docs/ReleaseNotes.rst
+++ docs/ReleaseNotes.rst
@@ -57,6 +57,11 @@
 Improvements to clang-tidy
 --------------------------
 
+- New :doc:`readability-redundant-data-call
+  <clang-tidy/checks/readability-redundant-data-call>` check
+
+  This check suggests removing redundant `.data()` calls.
+
 - New module `abseil` for checks related to the `Abseil <https://abseil.io>`_
   library.
 
Index: clang-tidy/readability/RedundantDataCallCheck.h
===================================================================
--- /dev/null
+++ clang-tidy/readability/RedundantDataCallCheck.h
@@ -0,0 +1,38 @@
+//===--- RedundantDataCallCheck.h - clang-tidy-------------------*- C++ -*-===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+
+#ifndef LLVM_CLANG_TOOLS_EXTRA_CLANG_TIDY_READABILITY_REDUNDANTDATACALLCHECK_H
+#define LLVM_CLANG_TOOLS_EXTRA_CLANG_TIDY_READABILITY_REDUNDANTDATACALLCHECK_H
+
+#include "../ClangTidy.h"
+
+namespace clang {
+namespace tidy {
+namespace readability {
+
+/// Find and remove redundant .data() calls.
+///
+/// For the user-facing documentation see:
+/// http://clang.llvm.org/extra/clang-tidy/checks/readability-redundant-data-call.html
+class RedundantDataCallCheck : public ClangTidyCheck {
+public:
+  RedundantDataCallCheck(StringRef Name, ClangTidyContext *Context);
+  void registerMatchers(ast_matchers::MatchFinder *Finder) override;
+  void check(const ast_matchers::MatchFinder::MatchResult &Result) override;
+  void storeOptions(ClangTidyOptions::OptionMap& Opts) override;
+
+private:
+  const std::vector<std::string> Types;
+};
+
+} // namespace readability
+} // namespace tidy
+} // namespace clang
+
+#endif // LLVM_CLANG_TOOLS_EXTRA_CLANG_TIDY_READABILITY_REDUNDANTDATACALLCHECK_H
Index: clang-tidy/readability/RedundantDataCallCheck.cpp
===================================================================
--- /dev/null
+++ clang-tidy/readability/RedundantDataCallCheck.cpp
@@ -0,0 +1,97 @@
+//===--- RedundantDataCallCheck.cpp - clang-tidy---------------------------===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+
+#include "RedundantDataCallCheck.h"
+#include "../utils/OptionsUtils.h"
+#include "clang/AST/ASTContext.h"
+#include "clang/ASTMatchers/ASTMatchFinder.h"
+
+using namespace clang::ast_matchers;
+
+namespace clang {
+namespace tidy {
+namespace readability {
+namespace {
+const char kDefaultTypes[] =
+    "::std::basic_string;::std::basic_string_view;::std::vector;::std::array";
+} // namespace
+
+RedundantDataCallCheck::RedundantDataCallCheck(StringRef Name,
+                                               ClangTidyContext *Context)
+    : ClangTidyCheck(Name, Context), Types(utils::options::parseStringList(
+                                         Options.get("Types", kDefaultTypes))) {
+}
+
+void RedundantDataCallCheck::registerMatchers(MatchFinder *Finder) {
+  using ast_matchers::allOf;
+  using ast_matchers::anyOf;
+  using ast_matchers::arraySubscriptExpr;
+  using ast_matchers::callee;
+  using ast_matchers::cxxMemberCallExpr;
+  using ast_matchers::cxxRecordDecl;
+  using ast_matchers::has;
+  using ast_matchers::hasAnyName;
+  using ast_matchers::hasBase;
+  using ast_matchers::hasDeclaration;
+  using ast_matchers::hasDescendant;
+  using ast_matchers::hasName;
+  using ast_matchers::hasType;
+  using ast_matchers::hasUnqualifiedDesugaredType;
+  using ast_matchers::ignoringParenImpCasts;
+  using ast_matchers::isArrow;
+  using ast_matchers::memberExpr;
+  using ast_matchers::namedDecl;
+  using ast_matchers::on;
+  using ast_matchers::pointee;
+  using ast_matchers::pointerType;
+  using ast_matchers::qualType;
+  using ast_matchers::recordType;
+  using ast_matchers::substTemplateTypeParmType;
+  using ast_matchers::unless;
+
+  const auto TypesMatcher = hasUnqualifiedDesugaredType(
+      recordType(hasDeclaration(cxxRecordDecl(hasAnyName(
+          llvm::SmallVector<StringRef, 8>(Types.begin(), Types.end()))))));
+
+  Finder->addMatcher(
+      arraySubscriptExpr(hasBase(ignoringParenImpCasts(
+          cxxMemberCallExpr(
+              has(memberExpr().bind("member")),
+              on(hasType(qualType(
+                  unless(anyOf(substTemplateTypeParmType(),
+                               hasDescendant(substTemplateTypeParmType()))),
+                  anyOf(TypesMatcher, pointerType(pointee(TypesMatcher)))))),
+              callee(namedDecl(hasName("data"))))
+              .bind("call")))),
+      this);
+}
+
+void RedundantDataCallCheck::check(const MatchFinder::MatchResult &Result) {
+  const auto *Call = Result.Nodes.getNodeAs<CXXMemberCallExpr>("call");
+  if (Result.Context->getSourceManager().isMacroBodyExpansion(
+          Call->getExprLoc())) {
+    return;
+  }
+  const auto *Member = Result.Nodes.getNodeAs<MemberExpr>("member");
+  auto DiagBuilder = diag(Member->getMemberLoc(), "redundant call to .data()");
+  if (Member->isArrow()) {
+    DiagBuilder << FixItHint::CreateInsertion(Member->getLocStart(), "(*")
+                << FixItHint::CreateInsertion(Member->getOperatorLoc(), ")");
+  }
+  DiagBuilder << FixItHint::CreateRemoval(
+      {Member->getOperatorLoc(), Call->getLocEnd()});
+}
+
+void RedundantDataCallCheck::storeOptions(ClangTidyOptions::OptionMap &Opts) {
+  Options.store(Opts, "Types", utils::options::serializeStringList(Types));
+}
+
+} // namespace readability
+} // namespace tidy
+} // namespace clang
Index: clang-tidy/readability/ReadabilityTidyModule.cpp
===================================================================
--- clang-tidy/readability/ReadabilityTidyModule.cpp
+++ clang-tidy/readability/ReadabilityTidyModule.cpp
@@ -25,6 +25,7 @@
 #include "NamedParameterCheck.h"
 #include "NonConstParameterCheck.h"
 #include "RedundantControlFlowCheck.h"
+#include "RedundantDataCallCheck.h"
 #include "RedundantDeclarationCheck.h"
 #include "RedundantFunctionPtrDereferenceCheck.h"
 #include "RedundantMemberInitCheck.h"
@@ -68,6 +69,8 @@
         "readability-misleading-indentation");
     CheckFactories.registerCheck<MisplacedArrayIndexCheck>(
         "readability-misplaced-array-index");
+    CheckFactories.registerCheck<RedundantDataCallCheck>(
+        "readability-redundant-data-call");
     CheckFactories.registerCheck<RedundantFunctionPtrDereferenceCheck>(
         "readability-redundant-function-ptr-dereference");
     CheckFactories.registerCheck<RedundantMemberInitCheck>(
Index: clang-tidy/readability/CMakeLists.txt
===================================================================
--- clang-tidy/readability/CMakeLists.txt
+++ clang-tidy/readability/CMakeLists.txt
@@ -18,6 +18,7 @@
   NonConstParameterCheck.cpp
   ReadabilityTidyModule.cpp
   RedundantControlFlowCheck.cpp
+  RedundantDataCallCheck.cpp
   RedundantDeclarationCheck.cpp
   RedundantFunctionPtrDereferenceCheck.cpp
   RedundantMemberInitCheck.cpp
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