[clang-tidy] Adding Fuchsia checker for virtual inheritance

Adds a check to the Fuchsia module to warn if classes are defined
with virtual inheritance.

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

Differential Revision: https://reviews.llvm.org/D40813

git-svn-id: https://llvm.org/svn/llvm-project/clang-tools-extra/trunk@320841 91177308-0d34-0410-b5e6-96231b3b80d8

4 files changed, 80 insertions, 0 deletions

diff --git a/clang-tidy/fuchsia/CMakeLists.txt b/clang-tidy/fuchsia/CMakeLists.txt
index 4a574197..692a3677 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
+  VirtualInheritanceCheck.cpp
 
   LINK_LIBS
   clangAST
diff --git a/clang-tidy/fuchsia/FuchsiaTidyModule.cpp b/clang-tidy/fuchsia/FuchsiaTidyModule.cpp
index 708272f9..5ed834d9 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 "VirtualInheritanceCheck.h"
 
 using namespace clang::ast_matchers;
 
@@ -24,6 +25,8 @@ public:
   void addCheckFactories(ClangTidyCheckFactories &CheckFactories) override {
     CheckFactories.registerCheck<DefaultArgumentsCheck>(
         "fuchsia-default-arguments");
+    CheckFactories.registerCheck<VirtualInheritanceCheck>(
+        "fuchsia-virtual-inheritance");
   }
 };
 // Register the FuchsiaTidyModule using this statically initialized variable.
diff --git a/clang-tidy/fuchsia/VirtualInheritanceCheck.cpp b/clang-tidy/fuchsia/VirtualInheritanceCheck.cpp
new file mode 100644
index 00000000..6f3b433a
--- /dev/null
+++ b/clang-tidy/fuchsia/VirtualInheritanceCheck.cpp
@@ -0,0 +1,41 @@
+//===--- VirtualInheritanceCheck.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 "VirtualInheritanceCheck.h"
+#include "clang/AST/ASTContext.h"
+#include "clang/ASTMatchers/ASTMatchFinder.h"
+
+using namespace clang::ast_matchers;
+
+namespace clang {
+namespace tidy {
+namespace fuchsia {
+
+AST_MATCHER(CXXRecordDecl, hasDirectVirtualBaseClass) {
+  if (!Node.hasDefinition()) return false;
+  if (!Node.getNumVBases()) return false;
+  for (const CXXBaseSpecifier &Base : Node.bases())
+    if (Base.isVirtual()) return true;
+  return false;
+}
+
+void VirtualInheritanceCheck::registerMatchers(MatchFinder *Finder) {
+  // Defining classes using direct virtual inheritance is disallowed.
+  Finder->addMatcher(cxxRecordDecl(hasDirectVirtualBaseClass()).bind("decl"),
+                     this);
+}
+
+void VirtualInheritanceCheck::check(const MatchFinder::MatchResult &Result) {
+  if (const auto *D = Result.Nodes.getNodeAs<CXXRecordDecl>("decl"))
+    diag(D->getLocStart(), "direct virtual inheritance is disallowed");
+}
+
+}  // namespace fuchsia
+}  // namespace tidy
+}  // namespace clang
diff --git a/clang-tidy/fuchsia/VirtualInheritanceCheck.h b/clang-tidy/fuchsia/VirtualInheritanceCheck.h
new file mode 100644
index 00000000..b2c84c41
--- /dev/null
+++ b/clang-tidy/fuchsia/VirtualInheritanceCheck.h
@@ -0,0 +1,35 @@
+//===--- VirtualInheritanceCheck.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_VIRTUAL_INHERITANCE_H
+#define LLVM_CLANG_TOOLS_EXTRA_CLANG_TIDY_FUCHSIA_VIRTUAL_INHERITANCE_H
+
+#include "../ClangTidy.h"
+
+namespace clang {
+namespace tidy {
+namespace fuchsia {
+
+/// Defining classes with virtual inheritance is disallowed.
+///
+/// For the user-facing documentation see:
+/// http://clang.llvm.org/extra/clang-tidy/checks/fuchsia-virtual-inheritance.html
+class VirtualInheritanceCheck : public ClangTidyCheck {
+ public:
+  VirtualInheritanceCheck(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_VIRTUAL_INHERITANCE_H