Check for public dtors on base::RefCounted types

tools/clang/plugins/FindBadConstructs.cpp

 // Copyright (c) 2011 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 // This file defines a bunch of recurring problems in the Chromium C++ code.
 //
 // Checks that are implemented:
 // - Constructors/Destructors should not be inlined if they are of a complex
 //   class type.
 // - Missing "virtual" keywords on methods that should be virtual.
 // - Non-annotated overriding virtual methods.
 // - Virtual methods with nonempty implementations in their headers.
 //
 // Things that are still TODO:
 // - Deriving from base::RefCounted and friends should mandate non-public
 //   destructors.
 
 #include "clang/Frontend/FrontendPluginRegistry.h"
 #include "clang/AST/ASTConsumer.h"
 #include "clang/AST/AST.h"
+#include "clang/AST/CXXInheritance.h"
 #include "clang/AST/TypeLoc.h"
 #include "clang/Basic/SourceManager.h"
 #include "clang/Frontend/CompilerInstance.h"
 #include "llvm/Support/raw_ostream.h"
 
 #include "ChromeClassTester.h"
 
 using namespace clang;
 
 namespace {
 
 bool TypeHasNonTrivialDtor(const Type* type) {
   if (const CXXRecordDecl* cxx_r = type->getCXXRecordDeclForPointerType())
     return cxx_r->hasTrivialDestructor();
 
   return false;
 }
 
+// Returns true if |base| specifies one of the Chromium reference counted
+// classes (base::RefCounted / base::RefCountedThreadSafe). |user_data| is
+// ignored.
+bool IsRefCounted(const CXXBaseSpecifier* base,
+                  CXXBasePath& path,
+                  void* user_data) {
+  if (base->getTypeSourceInfo()->getTypeLoc().getTypeLocClass() !=
+      TypeLoc::TemplateSpecialization) {
+    return false;
+  }
+
+  TemplateName name =
+      dyn_cast<TemplateSpecializationType>(base->getType())->getTemplateName();
+
+  if (TemplateDecl* decl = name.getAsTemplateDecl()) {
+    std::string base_name = decl->getNameAsString();

[Nico, 2012/04/05 23:08:13]

might want to check the namespace too

+    if (base_name.compare(0, 10, "RefCounted") == 0)
+      return true;
+  }
+  return false;
+}
+
 // Searches for constructs that we know we don't want in the Chromium code base.
 class FindBadConstructsConsumer : public ChromeClassTester {
  public:
   FindBadConstructsConsumer(CompilerInstance& instance)
       : ChromeClassTester(instance) {}
 
   virtual void CheckChromeClass(const SourceLocation& record_location,
                                 CXXRecordDecl* record) {
-    CheckCtorDtorWeight(record_location, record);
-    CheckVirtualMethods(record_location, record);
+    bool implementation_file = InImplementationFile(record_location);
+
+    if (!implementation_file) {
+      // Only check for "heavy" constructors/destructors in header files;
+      // within implementation files, there is no performance cost.
+      CheckCtorDtorWeight(record_location, record);
+    }
+
+    CheckRefCountedDtors(record_location, record);
+
+    // Check that all virtual methods are marked accordingly with both
+    // virtual and OVERRIDE. However, only warn on inline bodies for
+    // declarations in headers, not implementation files.
+    CheckVirtualMethods(record_location, record, !implementation_file);
+  }
+
+  // Prints errors if the destructor of a RefCounted class is public.
+  void CheckRefCountedDtors(const SourceLocation& record_location,
+                            CXXRecordDecl* record) {
+    // Skip anonymous structs.
+    if (record->getIdentifier() == NULL)
+      return;
+
+    CXXBasePaths paths;
+    if (!record->lookupInBases(&IsRefCounted, NULL, paths))
+      return;  // Class does not derive from a ref-counted base class.
+
+    if (!record->hasUserDeclaredDestructor()) {
+      emitWarning(
+          record_location,
+          "Classes that are ref-counted should have explicit "
+          "destructors that are protected or private.");
+    } else if (CXXDestructorDecl* dtor = record->getDestructor()) {
+      if (dtor->getAccess() == AS_public) {
+        emitWarning(
+            dtor->getInnerLocStart(),
+            "Classes that are ref-counted should not have "
+            "public destructors.");
+      }
+    }
   }
 
   // Prints errors if the constructor/destructor weight is too heavy.
   void CheckCtorDtorWeight(const SourceLocation& record_location,
                            CXXRecordDecl* record) {
     // We don't handle anonymous structs. If this record doesn't have a
     // name, it's of the form:
     //
     // struct {
     //   ...
@@ skipping 71 matching lines @@
             "destructor.");
       } else if (CXXDestructorDecl* dtor = record->getDestructor()) {
         if (dtor->hasInlineBody()) {
           emitWarning(dtor->getInnerLocStart(),
                       "Complex destructor has an inline body.");
         }
       }
     }
   }
 
-  void CheckVirtualMethod(const CXXMethodDecl* method) {
+  void CheckVirtualMethod(const CXXMethodDecl* method,
+                          bool warn_on_inline_bodies) {
     if (!method->isVirtual())
       return;
 
     if (!method->isVirtualAsWritten()) {
       SourceLocation loc = method->getTypeSpecStartLoc();
       if (isa<CXXDestructorDecl>(method))
         loc = method->getInnerLocStart();
       emitWarning(loc, "Overriding method must have \"virtual\" keyword.");
     }
 
-    // Virtual methods should not have inline definitions beyond "{}".
-    if (method->hasBody() && method->hasInlineBody()) {
+    // Virtual methods should not have inline definitions beyond "{}". This
+    // only matters for header files.
+    if (warn_on_inline_bodies && method->hasBody() &&
+        method->hasInlineBody()) {
       if (CompoundStmt* cs = dyn_cast<CompoundStmt>(method->getBody())) {
         if (cs->size()) {
           emitWarning(
               cs->getLBracLoc(),
               "virtual methods with non-empty bodies shouldn't be "
               "declared inline.");
         }
       }
     }
   }
@@ skipping 19 matching lines @@
     if (isa<CXXDestructorDecl>(method) || method->isPure())
       return;
 
     if (IsMethodInBannedNamespace(method))
       return;
 
     SourceLocation loc = method->getTypeSpecStartLoc();
     emitWarning(loc, "Overriding method must be marked with OVERRIDE.");
   }
 
-  // Makes sure there is a "virtual" keyword on virtual methods and that there
-  // are no inline function bodies on them (but "{}" is allowed).
+  // Makes sure there is a "virtual" keyword on virtual methods.
   //
   // Gmock objects trigger these for each MOCK_BLAH() macro used. So we have a
   // trick to get around that. If a class has member variables whose types are
   // in the "testing" namespace (which is how gmock works behind the scenes),
   // there's a really high chance we won't care about these errors
   void CheckVirtualMethods(const SourceLocation& record_location,
-                           CXXRecordDecl* record) {
+                           CXXRecordDecl* record,
+                           bool warn_on_inline_bodies) {
     for (CXXRecordDecl::field_iterator it = record->field_begin();
          it != record->field_end(); ++it) {
       CXXRecordDecl* record_type =
           it->getTypeSourceInfo()->getTypeLoc().getTypePtr()->
           getAsCXXRecordDecl();
       if (record_type) {
         if (InTestingNamespace(record_type)) {
           return;
         }
       }
     }
 
     for (CXXRecordDecl::method_iterator it = record->method_begin();
          it != record->method_end(); ++it) {
       if (it->isCopyAssignmentOperator() || isa<CXXConstructorDecl>(*it)) {
         // Ignore constructors and assignment operators.
       } else if (isa<CXXDestructorDecl>(*it) &&
           !record->hasUserDeclaredDestructor()) {
         // Ignore non-user-declared destructors.
       } else {
-        CheckVirtualMethod(*it);
+        CheckVirtualMethod(*it, warn_on_inline_bodies);
         CheckOverriddenMethod(*it);
       }
     }
   }
 
   void CountType(const Type* type,
                  int* trivial_member,
                  int* non_trivial_member,
                  int* templated_non_trivial_member) {
     switch (type->getTypeClass()) {
@@ skipping 60 matching lines @@
                  const std::vector<std::string>& args) {
     // We don't take any additional arguments here.
     return true;
   }
 };
 
 }  // namespace
 
 static FrontendPluginRegistry::Add<FindBadConstructsAction>
 X("find-bad-constructs", "Finds bad C++ constructs");