[clang-tidy] Adding Fuchsia checker for overloaded operators

Adds a check to the Fuchsia module to warn if an operator is overloaded,
except move and copy operators.

See https://fuchsia.googlesource.com/zircon/+/master/docs/cxx.md for
reference.

Differential Revision: https://reviews.llvm.org/D41363

git-svn-id: https://llvm.org/svn/llvm-project/clang-tools-extra/trunk@321363 91177308-0d34-0410-b5e6-96231b3b80d8

4 files changed, 78 insertions, 0 deletions

diff --git a/clang-tidy/fuchsia/CMakeLists.txt b/clang-tidy/fuchsia/CMakeLists.txt
index 692a3677..3b223ba7 100644
--- a/clang-tidy/fuchsia/CMakeLists.txt
+++ b/clang-tidy/fuchsia/CMakeLists.txt
@@ -3,6 +3,7 @@ set(LLVM_LINK_COMPONENTS support)
 add_clang_library(clangTidyFuchsiaModule
   DefaultArgumentsCheck.cpp
   FuchsiaTidyModule.cpp
+  OverloadedOperatorCheck.cpp
   VirtualInheritanceCheck.cpp
 
   LINK_LIBS
diff --git a/clang-tidy/fuchsia/FuchsiaTidyModule.cpp b/clang-tidy/fuchsia/FuchsiaTidyModule.cpp
index 5ed834d9..1860115a 100644
--- a/clang-tidy/fuchsia/FuchsiaTidyModule.cpp
+++ b/clang-tidy/fuchsia/FuchsiaTidyModule.cpp
@@ -11,6 +11,7 @@
 #include "../ClangTidyModule.h"
 #include "../ClangTidyModuleRegistry.h"
 #include "DefaultArgumentsCheck.h"
+#include "OverloadedOperatorCheck.h"
 #include "VirtualInheritanceCheck.h"
 
 using namespace clang::ast_matchers;
@@ -25,6 +26,8 @@ public:
   void addCheckFactories(ClangTidyCheckFactories &CheckFactories) override {
     CheckFactories.registerCheck<DefaultArgumentsCheck>(
         "fuchsia-default-arguments");
+    CheckFactories.registerCheck<OverloadedOperatorCheck>(
+        "fuchsia-overloaded-operator");
     CheckFactories.registerCheck<VirtualInheritanceCheck>(
         "fuchsia-virtual-inheritance");
   }
diff --git a/clang-tidy/fuchsia/OverloadedOperatorCheck.cpp b/clang-tidy/fuchsia/OverloadedOperatorCheck.cpp
new file mode 100644
index 00000000..57b4628c
--- /dev/null
+++ b/clang-tidy/fuchsia/OverloadedOperatorCheck.cpp
@@ -0,0 +1,39 @@
+//===--- OverloadedOperatorCheck.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 "OverloadedOperatorCheck.h"
+
+using namespace clang::ast_matchers;
+
+namespace clang {
+namespace tidy {
+namespace fuchsia {
+
+AST_MATCHER(FunctionDecl, isFuchsiaOverloadedOperator) {
+  if (const auto *CXXMethodNode = dyn_cast<CXXMethodDecl>(&Node)) {
+    if (CXXMethodNode->isCopyAssignmentOperator() ||
+        CXXMethodNode->isMoveAssignmentOperator())
+      return false;
+  }
+  return Node.isOverloadedOperator();
+}
+
+void OverloadedOperatorCheck::registerMatchers(MatchFinder *Finder) {
+  Finder->addMatcher(functionDecl(isFuchsiaOverloadedOperator()).bind("decl"),
+                     this);
+}
+
+void OverloadedOperatorCheck::check(const MatchFinder::MatchResult &Result) {
+  if (const auto *D = Result.Nodes.getNodeAs<FunctionDecl>("decl"))
+    diag(D->getLocStart(), "cannot overload %0") << D;
+}
+
+} // namespace fuchsia
+} // namespace tidy
+} // namespace clang
diff --git a/clang-tidy/fuchsia/OverloadedOperatorCheck.h b/clang-tidy/fuchsia/OverloadedOperatorCheck.h
new file mode 100644
index 00000000..a22e5ae5
--- /dev/null
+++ b/clang-tidy/fuchsia/OverloadedOperatorCheck.h
@@ -0,0 +1,35 @@
+//===--- OverloadedOperatorCheck.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_FUCHSIA_OVERLOADED_OPERATOR_H
+#define LLVM_CLANG_TOOLS_EXTRA_CLANG_TIDY_FUCHSIA_OVERLOADED_OPERATOR_H
+
+#include "../ClangTidy.h"
+
+namespace clang {
+namespace tidy {
+namespace fuchsia {
+
+/// Overloading operators is disallowed by the Fuchsia coding standard.
+///
+/// For the user-facing documentation see:
+/// http://clang.llvm.org/extra/clang-tidy/checks/fuchsia-overloaded-operator.html
+class OverloadedOperatorCheck : public ClangTidyCheck {
+public:
+  OverloadedOperatorCheck(StringRef Name, ClangTidyContext *Context)
+      : ClangTidyCheck(Name, Context) {}
+  void registerMatchers(ast_matchers::MatchFinder *Finder) override;
+  void check(const ast_matchers::MatchFinder::MatchResult &Result) override;
+};
+
+} // namespace fuchsia
+} // namespace tidy
+} // namespace clang
+
+#endif // LLVM_CLANG_TOOLS_EXTRA_CLANG_TIDY_FUCHSIA_OVERLOADED_OPERATOR_H