[clang-tidy] Add a checker that flags all instances of overloaded unary operator&

[bkramer]

Summary

This handles both methods and freestanding overloads.

[alexfh]

clang-tidy/google/OverloadedUnaryAndCheck.cpp

31

Why is the outer matcher just "decl" and not "functionDecl"?

39

The original cpplint.py message is not very clear. I think, it should say "do not overload it".

test/clang-tidy/google-overloaded-unary-and.cpp

2

With -implicit-check-not it becomes bulky. We should make both CHECK-MESSAGES and CHECK-FIXES optional in check_clang_tidy_fix.sh and give the script a more generic name.

There's no need to do it in this patch, though.

5

How about tests with template instantiations? ;)

[bkramer]

• Reworded message
• Added test with template instance. Not as valuable here as with the other checkers as we don't have fixits.

[alexfh]

Looks good!

[bkramer]

Closed by commit rL213067 (authored by d0k).

clang-tidy/google/CMakeLists.txt

 set(LLVM_LINK_COMPONENTS support)
 
 add_clang_library(clangTidyGoogleModule
   AvoidCStyleCastsCheck.cpp
   ExplicitConstructorCheck.cpp
   ExplicitMakePairCheck.cpp
   GoogleTidyModule.cpp
+  OverloadedUnaryAndCheck.cpp
 
   LINK_LIBS
   clangAST
   clangASTMatchers
   clangBasic
   clangLex
   clangTidy
   )

clang-tidy/google/GoogleTidyModule.cpp

 //===--- GoogleTidyModule.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 "../ClangTidy.h"
 #include "../ClangTidyModule.h"
 #include "../ClangTidyModuleRegistry.h"
 #include "AvoidCStyleCastsCheck.h"
 #include "ExplicitConstructorCheck.h"
 #include "ExplicitMakePairCheck.h"
+#include "OverloadedUnaryAndCheck.h"
 
 using namespace clang::ast_matchers;
 
 namespace clang {
 namespace tidy {
 
 class GoogleModule : public ClangTidyModule {
 public:
   void addCheckFactories(ClangTidyCheckFactories &CheckFactories) override {
     CheckFactories.addCheckFactory(
         "google-build-explicit-make-pair",
         new ClangTidyCheckFactory<build::ExplicitMakePairCheck>());
     CheckFactories.addCheckFactory(
         "google-explicit-constructor",
         new ClangTidyCheckFactory<ExplicitConstructorCheck>());
     CheckFactories.addCheckFactory(
+        "google-runtime-operator",
+        new ClangTidyCheckFactory<runtime::OverloadedUnaryAndCheck>());
+    CheckFactories.addCheckFactory(
         "google-readability-casting",
         new ClangTidyCheckFactory<readability::AvoidCStyleCastsCheck>());
   }
 };
 
 // Register the GoogleTidyModule using this statically initialized variable.
 static ClangTidyModuleRegistry::Add<GoogleModule> X("google-module",
                                                     "Adds Google lint checks.");
 
 // This anchor is used to force the linker to link in the generated object file
 // and thus register the GoogleModule.
 volatile int GoogleModuleAnchorSource = 0;
 
 } // namespace tidy
 } // namespace clang

clang-tidy/google/OverloadedUnaryAndCheck.h

+//===--- OverloadedUnaryAndCheck.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_GOOGLE_OVERLOADED_UNARY_AND_CHECK_H
+#define LLVM_CLANG_TOOLS_EXTRA_CLANG_TIDY_GOOGLE_OVERLOADED_UNARY_AND_CHECK_H
+
+#include "../ClangTidy.h"
+
+namespace clang {
+namespace tidy {
+namespace runtime {
+
+/// \brief Finds overloads of unary operator &.
+///
+/// Corresponding cpplint.py check name: 'runtime/operator'.
+class OverloadedUnaryAndCheck : public ClangTidyCheck {
+public:
+  void registerMatchers(ast_matchers::MatchFinder *Finder) override;
+  void check(const ast_matchers::MatchFinder::MatchResult &Result) override;
+};
+
+} // namespace runtime
+} // namespace tidy
+} // namespace clang
+
+#endif // LLVM_CLANG_TOOLS_EXTRA_CLANG_TIDY_GOOGLE_OVERLOADED_UNARY_AND_CHECK_H

clang-tidy/google/OverloadedUnaryAndCheck.cpp

+//===--- OverloadedUnaryAndCheck.cpp - clang-tidy ---------------*- C++ -*-===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+
+#include "OverloadedUnaryAndCheck.h"
+#include "clang/ASTMatchers/ASTMatchFinder.h"
+#include "clang/ASTMatchers/ASTMatchers.h"
+#include "clang/AST/ASTContext.h"
+
+using namespace clang::ast_matchers;
+
+namespace clang {
+namespace tidy {
+namespace runtime {
+
+void
+OverloadedUnaryAndCheck::registerMatchers(ast_matchers::MatchFinder *Finder) {
+  // Match unary methods that overload operator&.
+  Finder->addMatcher(methodDecl(parameterCountIs(0), hasOverloadedOperatorName(
+                                                         "&")).bind("overload"),
+                     this);
+  // Also match freestanding unary operator& overloads. Be careful not to match
+  // binary methods.
+  Finder->addMatcher(
+      functionDecl(
+          allOf(unless(methodDecl()),
+                functionDecl(parameterCountIs(1),
+                             hasOverloadedOperatorName("&")).bind("overload"))),
+      this);
+}
+
+void OverloadedUnaryAndCheck::check(const MatchFinder::MatchResult &Result) {
+  const auto *Decl = Result.Nodes.getNodeAs<FunctionDecl>("overload");
+  diag(Decl->getLocStart(),
+       "do not overload unary operator&, it is dangerous.");
+}
+
+} // namespace runtime
+} // namespace tidy
+} // namespace clang

test/clang-tidy/google-overloaded-unary-and.cpp

+// RUN: clang-tidy %s -checks='-*,google-runtime-operator' -- | FileCheck %s -implicit-check-not="{{warning|error}}:"
+
+struct Foo {
+  void *operator&();
+// CHECK: :[[@LINE-1]]:3: warning: do not overload unary operator&, it is dangerous.
+};
+
+template <typename T>
+struct TFoo {
+  T *operator&();
+// CHECK: :[[@LINE-1]]:3: warning: do not overload unary operator&, it is dangerous.
+};
+
+TFoo<int> tfoo;
+
+struct Bar;
+void *operator&(Bar &b);
+// CHECK: :[[@LINE-1]]:1: warning: do not overload unary operator&, it is dangerous.
+
+struct Qux {
+  void *operator&(Qux &q); // no-warning
+};
+
+void *operator&(Qux &q, Qux &r); // no-warning