[clang-tidy]: Added modernize-replace-disallow-copy-and-assign-macro

Summary:
This check finds macro expansions of `DISALLOW_COPY_AND_ASSIGN(Type)` and
replaces them with a deleted copy constructor and a deleted assignment operator.

Before the `delete` keyword was introduced in C++11 it was common practice to
declare a copy constructor and an assignment operator as a private members. This
effectively makes them unusable to the public API of a class.

With the advent of the `delete` keyword in C++11 we can abandon the
`private` access of the copy constructor and the assignment operator and
delete the methods entirely.

Migration example:

```
lang=dif
class Foo {
  private:
  -  DISALLOW_COPY_AND_ASSIGN(Foo);
  +  Foo(const Foo &) = delete;
  +  const Foo &operator=(const Foo &) = delete;
  };
```

Reviewers: alexfh, hokein, aaron.ballman, njames93

Reviewed By: njames93

Subscribers: Eugene.Zelenko, mgorny, xazax.hun, cfe-commits

Tags: #clang, #clang-tools-extra

Differential Revision: https://reviews.llvm.org/D80531

clang-tools-extra/clang-tidy/modernize/CMakeLists.txt

@@ -19,6 +19,7 @@ add_clang_library(clangTidyModernizeModule
   RawStringLiteralCheck.cpp
   RedundantVoidArgCheck.cpp
   ReplaceAutoPtrCheck.cpp
+  ReplaceDisallowCopyAndAssignMacroCheck.cpp
   ReplaceRandomShuffleCheck.cpp
   ReturnBracedInitListCheck.cpp
   ShrinkToFitCheck.cpp

clang-tools-extra/clang-tidy/modernize/ModernizeTidyModule.cpp

@@ -21,6 +21,7 @@
 #include "RawStringLiteralCheck.h"
 #include "RedundantVoidArgCheck.h"
 #include "ReplaceAutoPtrCheck.h"
+#include "ReplaceDisallowCopyAndAssignMacroCheck.h"
 #include "ReplaceRandomShuffleCheck.h"
 #include "ReturnBracedInitListCheck.h"
 #include "ShrinkToFitCheck.h"
@@ -67,6 +68,8 @@ public:
         "modernize-redundant-void-arg");
     CheckFactories.registerCheck<ReplaceAutoPtrCheck>(
         "modernize-replace-auto-ptr");
+    CheckFactories.registerCheck<ReplaceDisallowCopyAndAssignMacroCheck>(
+        "modernize-replace-disallow-copy-and-assign-macro");
     CheckFactories.registerCheck<ReplaceRandomShuffleCheck>(
         "modernize-replace-random-shuffle");
     CheckFactories.registerCheck<ReturnBracedInitListCheck>(

clang-tools-extra/clang-tidy/modernize/ReplaceDisallowCopyAndAssignMacroCheck.cpp

@@ -0,0 +1,90 @@
+//===--- ReplaceDisallowCopyAndAssignMacroCheck.cpp - clang-tidy ----------===//
+//
+// 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 "ReplaceDisallowCopyAndAssignMacroCheck.h"
+#include "clang/Frontend/CompilerInstance.h"
+#include "clang/Lex/MacroArgs.h"
+#include "llvm/Support/FormatVariadic.h"
+
+namespace clang {
+namespace tidy {
+namespace modernize {
+
+namespace {
+
+class ReplaceDisallowCopyAndAssignMacroCallbacks : public PPCallbacks {
+public:
+  explicit ReplaceDisallowCopyAndAssignMacroCallbacks(
+      ReplaceDisallowCopyAndAssignMacroCheck &Check, Preprocessor &PP)
+      : Check(Check), PP(PP) {}
+
+  void MacroExpands(const Token &MacroNameTok, const MacroDefinition &MD,
+                    SourceRange Range, const MacroArgs *Args) override {
+    IdentifierInfo *Info = MacroNameTok.getIdentifierInfo();
+    if (!Info || !Args || Args->getNumMacroArguments() != 1)
+      return;
+    if (Info->getName() != Check.getMacroName())
+      return;
+    // The first argument to the DISALLOW_COPY_AND_ASSIGN macro is exptected to
+    // be the class name.
+    const Token *ClassNameTok = Args->getUnexpArgument(0);
+    if (Args->ArgNeedsPreexpansion(ClassNameTok, PP))
+      // For now we only support simple argument that don't need to be
+      // pre-expanded.
+      return;
+    clang::IdentifierInfo *ClassIdent = ClassNameTok->getIdentifierInfo();
+    if (!ClassIdent)
+      return;
+
+    std::string Replacement = llvm::formatv(
+        R"cpp({0}(const {0} &) = delete;
+const {0} &operator=(const {0} &) = delete{1})cpp",
+        ClassIdent->getName(), shouldAppendSemi(Range) ? ";" : "");
+
+    Check.diag(MacroNameTok.getLocation(),
+               "prefer deleting copy constructor and assignment operator over "
+               "using macro '%0'")
+        << Check.getMacroName()
+        << FixItHint::CreateReplacement(
+               PP.getSourceManager().getExpansionRange(Range), Replacement);
+  }
+
+private:
+  /// \returns \c true if the next token after the given \p MacroLoc is \b not a
+  /// semicolon.
+  bool shouldAppendSemi(SourceRange MacroLoc) {
+    llvm::Optional<Token> Next = Lexer::findNextToken(
+        MacroLoc.getEnd(), PP.getSourceManager(), PP.getLangOpts());
+    return !(Next && Next->is(tok::semi));
+  }
+
+  ReplaceDisallowCopyAndAssignMacroCheck &Check;
+  Preprocessor &PP;
+};
+} // namespace
+
+ReplaceDisallowCopyAndAssignMacroCheck::ReplaceDisallowCopyAndAssignMacroCheck(
+    StringRef Name, ClangTidyContext *Context)
+    : ClangTidyCheck(Name, Context),
+      MacroName(Options.get("MacroName", "DISALLOW_COPY_AND_ASSIGN")) {}
+
+void ReplaceDisallowCopyAndAssignMacroCheck::registerPPCallbacks(
+    const SourceManager &SM, Preprocessor *PP, Preprocessor *ModuleExpanderPP) {
+  PP->addPPCallbacks(
+      ::std::make_unique<ReplaceDisallowCopyAndAssignMacroCallbacks>(
+          *this, *ModuleExpanderPP));
+}
+
+void ReplaceDisallowCopyAndAssignMacroCheck::storeOptions(
+    ClangTidyOptions::OptionMap &Opts) {
+  Options.store(Opts, "MacroName", MacroName);
+}
+
+} // namespace modernize
+} // namespace tidy
+} // namespace clang

clang-tools-extra/clang-tidy/modernize/ReplaceDisallowCopyAndAssignMacroCheck.h

@@ -0,0 +1,62 @@
+//===--- ReplaceDisallowCopyAndAssignMacroCheck.h - clang-tidy --*- 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_TOOLS_EXTRA_CLANG_TIDY_MODERNIZE_REPLACEDISALLOWCOPYANDASSIGNMACROCHECK_H
+#define LLVM_CLANG_TOOLS_EXTRA_CLANG_TIDY_MODERNIZE_REPLACEDISALLOWCOPYANDASSIGNMACROCHECK_H
+
+#include "../ClangTidyCheck.h"
+
+namespace clang {
+namespace tidy {
+namespace modernize {
+
+/// This check finds macro expansions of ``DISALLOW_COPY_AND_ASSIGN(Type)`` and
+/// replaces them with a deleted copy constructor and a deleted assignment
+/// operator.
+///
+/// Before:
+/// ~~~{.cpp}
+///   class Foo {
+///   private:
+///     DISALLOW_COPY_AND_ASSIGN(Foo);
+///   };
+/// ~~~
+///
+/// After:
+/// ~~~{.cpp}
+///   class Foo {
+///   private:
+///     Foo(const Foo &) = delete;
+///     const Foo &operator=(const Foo &) = delete;
+///   };
+/// ~~~
+///
+/// For the user-facing documentation see:
+/// http://clang.llvm.org/extra/clang-tidy/checks/modernize-replace-disallow-copy-and-assign-macro.html
+class ReplaceDisallowCopyAndAssignMacroCheck : public ClangTidyCheck {
+public:
+  ReplaceDisallowCopyAndAssignMacroCheck(StringRef Name,
+                                         ClangTidyContext *Context);
+  bool isLanguageVersionSupported(const LangOptions &LangOpts) const override {
+    return LangOpts.CPlusPlus11;
+  }
+  void registerPPCallbacks(const SourceManager &SM, Preprocessor *PP,
+                           Preprocessor *ModuleExpanderPP) override;
+  void storeOptions(ClangTidyOptions::OptionMap &Opts) override;
+
+  const std::string &getMacroName() const { return MacroName; }
+
+private:
+  const std::string MacroName;
+};
+
+} // namespace modernize
+} // namespace tidy
+} // namespace clang
+
+#endif // LLVM_CLANG_TOOLS_EXTRA_CLANG_TIDY_MODERNIZE_REPLACEDISALLOWCOPYANDASSIGNMACROCHECK_H

clang-tools-extra/docs/ReleaseNotes.rst

@@ -136,6 +136,12 @@ New checks
   Finds includes of system libc headers not provided by the compiler within
   llvm-libc implementations.
 
+- New :doc:`modernize-replace-disallow-copy-and-assign-macro
+  <clang-tidy/checks/modernize-replace-disallow-copy-and-assign-macro>` check.
+
+  Finds macro expansions of ``DISALLOW_COPY_AND_ASSIGN`` and replaces them with
+  a deleted copy constructor and a deleted assignment operator.
+
 - New :doc:`objc-dealloc-in-category
   <clang-tidy/checks/objc-dealloc-in-category>` check.
 

clang-tools-extra/docs/clang-tidy/checks/list.rst

@@ -218,6 +218,7 @@ Clang-Tidy Checks
    `modernize-raw-string-literal <modernize-raw-string-literal.html>`_, "Yes"
    `modernize-redundant-void-arg <modernize-redundant-void-arg.html>`_, "Yes"
    `modernize-replace-auto-ptr <modernize-replace-auto-ptr.html>`_, "Yes"
+   `modernize-replace-disallow-copy-and-assign-macro <modernize-replace-disallow-copy-and-assign-macro.html>`_, "Yes"
    `modernize-replace-random-shuffle <modernize-replace-random-shuffle.html>`_, "Yes"
    `modernize-return-braced-init-list <modernize-return-braced-init-list.html>`_, "Yes"
    `modernize-shrink-to-fit <modernize-shrink-to-fit.html>`_, "Yes"

clang-tools-extra/docs/clang-tidy/checks/modernize-replace-disallow-copy-and-assign-macro.rst

@@ -0,0 +1,52 @@
+.. title:: clang-tidy - modernize-replace-disallow-copy-and-assign-macro
+
+modernize-replace-disallow-copy-and-assign-macro
+================================================
+
+Finds macro expansions of ``DISALLOW_COPY_AND_ASSIGN(Type)`` and replaces them
+with a deleted copy constructor and a deleted assignment operator.
+
+Before the ``delete`` keyword was introduced in C++11 it was common practice to
+declare a copy constructor and an assignment operator as a private members. This
+effectively makes them unusable to the public API of a class.
+
+With the advent of the ``delete`` keyword in C++11 we can abandon the
+``private`` access of the copy constructor and the assignment operator and
+delete the methods entirely.
+
+When running this check on a code like this:
+
+.. code-block:: c++
+
+  class Foo {
+  private:
+    DISALLOW_COPY_AND_ASSIGN(Foo);
+  };
+
+It will be transformed to this:
+
+.. code-block:: c++
+
+  class Foo {
+  private:
+    Foo(const Foo &) = delete;
+    const Foo &operator=(const Foo &) = delete;
+  };
+
+Known Limitations
+-----------------
+
+* Notice that the migration example above leaves the ``private`` access
+  specification untouched. You might want to run the check:doc:`modernize-use-equals-delete
+  <modernize-use-equals-delete>` to get warnings for deleted functions in
+  private sections.
+
+Options
+-------
+
+.. option:: MacroName
+
+   A string specifying the macro name whose expansion will be replaced.
+   Default is `DISALLOW_COPY_AND_ASSIGN`.
+
+See: https://en.cppreference.com/w/cpp/language/function#Deleted_functions

clang-tools-extra/test/clang-tidy/checkers/modernize-replace-disallow-copy-and-assign-macro.cpp

@@ -0,0 +1,79 @@
+// RUN: %check_clang_tidy -format-style=LLVM -check-suffix=DEFAULT %s \
+// RUN:   modernize-replace-disallow-copy-and-assign-macro %t
+
+// RUN: %check_clang_tidy -format-style=LLVM -check-suffix=DIFFERENT-NAME %s \
+// RUN:  modernize-replace-disallow-copy-and-assign-macro %t \
+// RUN:  -config="{CheckOptions: [ \
+// RUN:   {key: modernize-replace-disallow-copy-and-assign-macro.MacroName, \
+// RUN:    value: MY_MACRO_NAME}]}"
+
+// RUN: %check_clang_tidy -format-style=LLVM -check-suffix=FINALIZE %s \
+// RUN:  modernize-replace-disallow-copy-and-assign-macro %t \
+// RUN:  -config="{CheckOptions: [ \
+// RUN:   {key: modernize-replace-disallow-copy-and-assign-macro.MacroName, \
+// RUN:    value: DISALLOW_COPY_AND_ASSIGN_FINALIZE}]}"
+
+// RUN: clang-tidy %s -checks="-*,modernize-replace-disallow-copy-and-assign-macro" \
+// RUN:   -config="{CheckOptions: [ \
+// RUN:    {key: modernize-replace-disallow-copy-and-assign-macro.MacroName, \
+// RUN:     value: DISALLOW_COPY_AND_ASSIGN_MORE_AGUMENTS}]}" | count 0
+
+// RUN: clang-tidy %s -checks="-*,modernize-replace-disallow-copy-and-assign-macro" \
+// RUN:   -config="{CheckOptions: [ \
+// RUN:    {key: modernize-replace-disallow-copy-and-assign-macro.MacroName, \
+// RUN:     value: DISALLOW_COPY_AND_ASSIGN_NEEDS_PREEXPANSION}]}" | count 0
+
+// Note: the last two tests expect no diagnostics, but FileCheck cannot handle
+// that, hence the use of | count 0.
+
+#define DISALLOW_COPY_AND_ASSIGN(TypeName)
+
+class TestClass1 {
+private:
+  DISALLOW_COPY_AND_ASSIGN(TestClass1);
+};
+// CHECK-MESSAGES-DEFAULT: :[[@LINE-2]]:3: warning: prefer deleting copy constructor and assignment operator over using macro 'DISALLOW_COPY_AND_ASSIGN' [modernize-replace-disallow-copy-and-assign-macro]
+// CHECK-FIXES-DEFAULT:      {{^}}  TestClass1(const TestClass1 &) = delete;{{$}}
+// CHECK-FIXES-DEFAULT-NEXT: {{^}}  const TestClass1 &operator=(const TestClass1 &) = delete;{{$}}
+
+#define MY_MACRO_NAME(TypeName)
+
+class TestClass2 {
+private:
+  MY_MACRO_NAME(TestClass2);
+};
+// CHECK-MESSAGES-DIFFERENT-NAME: :[[@LINE-2]]:3: warning: prefer deleting copy constructor and assignment operator over using macro 'MY_MACRO_NAME' [modernize-replace-disallow-copy-and-assign-macro]
+// CHECK-FIXES-DIFFERENT-NAME:      {{^}}  TestClass2(const TestClass2 &) = delete;{{$}}
+// CHECK-FIXES-DIFFERENT-NAME-NEXT: {{^}}  const TestClass2 &operator=(const TestClass2 &) = delete;{{$}}
+
+#define DISALLOW_COPY_AND_ASSIGN_FINALIZE(TypeName) \
+  TypeName(const TypeName &) = delete;              \
+  const TypeName &operator=(const TypeName &) = delete;
+
+class TestClass3 {
+private:
+  // Notice, that the macro allows to be used without a semicolon because the
+  // macro definition already contains one above. Therefore our replacement must
+  // contain a semicolon at the end.
+  DISALLOW_COPY_AND_ASSIGN_FINALIZE(TestClass3)
+};
+// CHECK-MESSAGES-FINALIZE: :[[@LINE-2]]:3: warning: prefer deleting copy constructor and assignment operator over using macro 'DISALLOW_COPY_AND_ASSIGN_FINALIZE' [modernize-replace-disallow-copy-and-assign-macro]
+// CHECK-FIXES-FINALIZE:      {{^}}  TestClass3(const TestClass3 &) = delete;{{$}}
+// CHECK-FIXES-FINALIZE-NEXT: {{^}}  const TestClass3 &operator=(const TestClass3 &) = delete;{{$}}
+
+#define DISALLOW_COPY_AND_ASSIGN_MORE_AGUMENTS(A, B)
+
+class TestClass4 {
+private:
+  DISALLOW_COPY_AND_ASSIGN_MORE_AGUMENTS(TestClass4, TestClass4);
+};
+// CHECK-MESSAGES-MORE-ARGUMENTS-NOT: warning: prefer deleting copy constructor and assignment operator over using macro 'DISALLOW_COPY_AND_ASSIGN_MORE_AGUMENTS'
+
+#define DISALLOW_COPY_AND_ASSIGN_NEEDS_PREEXPANSION(A)
+#define TESTCLASS TestClass5
+
+class TestClass5 {
+private:
+  DISALLOW_COPY_AND_ASSIGN_NEEDS_PREEXPANSION(TESTCLASS);
+};
+// CHECK-MESSAGES-MORE-ARGUMENTS-NOT: warning: prefer deleting copy constructor and assignment operator over using macro 'DISALLOW_COPY_AND_ASSIGN_NEEDS_PREEXPANSION'