The Tor Browser: media/webrtc/trunk/tools/clang/plugins/FindBadConstructs.cpp@925c144e1f1f (annotated)

media/webrtc/trunk/tools/clang/plugins/FindBadConstructs.cpp@925c144e1f1f (annotated)

media/webrtc/trunk/tools/clang/plugins/FindBadConstructs.cpp

Fri, 16 Jan 2015 18:13:44 +0100

author: Michael Schloh von Bennewitz <michael@schloh.com>
date: Fri, 16 Jan 2015 18:13:44 +0100
branch: TOR_BUG_9701
changeset 14: 925c144e1f1f
permissions: -rw-r--r--

Integrate suggestion from review to improve consistency with existing code.

 // Copyright (c) 2012 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.
 // - Classes that derive from base::RefCounted / base::RefCountedThreadSafe
 //   should have protected or private 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 the underlying Type for |type| by expanding typedefs and removing
 // any namespace qualifiers.
 const Type* UnwrapType(const Type* type) {
   if (const ElaboratedType* elaborated = dyn_cast<ElaboratedType>(type))
     return UnwrapType(elaborated->getNamedType().getTypePtr());
   if (const TypedefType* typedefed = dyn_cast<TypedefType>(type))
     return UnwrapType(typedefed->desugar().getTypePtr());
   return type;
 }
 // Searches for constructs that we know we don't want in the Chromium code base.
 class FindBadConstructsConsumer : public ChromeClassTester {
  public:
   FindBadConstructsConsumer(CompilerInstance& instance,
                             bool check_refcounted_dtors,
                             bool check_virtuals_in_implementations)
       : ChromeClassTester(instance),
         check_refcounted_dtors_(check_refcounted_dtors),
         check_virtuals_in_implementations_(check_virtuals_in_implementations) {
   }
   virtual void CheckChromeClass(SourceLocation record_location,
                                 CXXRecordDecl* 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);
     }
     if (!implementation_file || check_virtuals_in_implementations_) {
       bool warn_on_inline_bodies = !implementation_file;
       // Check that all virtual methods are marked accordingly with both
       // virtual and OVERRIDE.
       CheckVirtualMethods(record_location, record, warn_on_inline_bodies);
     }
     if (check_refcounted_dtors_)
       CheckRefCountedDtors(record_location, record);
   }
  private:
   bool check_refcounted_dtors_;
   bool check_virtuals_in_implementations_;
   // Returns true if |base| specifies one of the Chromium reference counted
   // classes (base::RefCounted / base::RefCountedThreadSafe). |user_data| is
   // ignored.
   static bool IsRefCountedCallback(const CXXBaseSpecifier* base,
                                    CXXBasePath& path,
                                    void* user_data) {
     FindBadConstructsConsumer* self =
         static_cast<FindBadConstructsConsumer*>(user_data);
     const TemplateSpecializationType* base_type =
         dyn_cast<TemplateSpecializationType>(
             UnwrapType(base->getType().getTypePtr()));
     if (!base_type) {
       // Base-most definition is not a template, so this cannot derive from
       // base::RefCounted. However, it may still be possible to use with a
       // scoped_refptr<> and support ref-counting, so this is not a perfect
       // guarantee of safety.
       return false;
     }
     TemplateName name = base_type->getTemplateName();
     if (TemplateDecl* decl = name.getAsTemplateDecl()) {
       std::string base_name = decl->getNameAsString();
       // Check for both base::RefCounted and base::RefCountedThreadSafe.
       if (base_name.compare(0, 10, "RefCounted") == 0 &&
           self->GetNamespace(decl) == "base") {
         return true;
       }
     }
     return false;
   }
   // Prints errors if the destructor of a RefCounted class is public.
   void CheckRefCountedDtors(SourceLocation record_location,
                             CXXRecordDecl* record) {
     // Skip anonymous structs.
     if (record->getIdentifier() == NULL)
       return;
     CXXBasePaths paths;
     if (!record->lookupInBases(
             &FindBadConstructsConsumer::IsRefCountedCallback, this, 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(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 {
     //   ...
     // } name_;
     if (record->getIdentifier() == NULL)
       return;
     // Count the number of templated base classes as a feature of whether the
     // destructor can be inlined.
     int templated_base_classes = 0;
     for (CXXRecordDecl::base_class_const_iterator it = record->bases_begin();
          it != record->bases_end(); ++it) {
       if (it->getTypeSourceInfo()->getTypeLoc().getTypeLocClass() ==
           TypeLoc::TemplateSpecialization) {
         ++templated_base_classes;
       }
     }
     // Count the number of trivial and non-trivial member variables.
     int trivial_member = 0;
     int non_trivial_member = 0;
     int templated_non_trivial_member = 0;
     for (RecordDecl::field_iterator it = record->field_begin();
          it != record->field_end(); ++it) {
       CountType(it->getType().getTypePtr(),
                 &trivial_member,
                 &non_trivial_member,
                 &templated_non_trivial_member);
     }
     // Check to see if we need to ban inlined/synthesized constructors. Note
     // that the cutoffs here are kind of arbitrary. Scores over 10 break.
     int dtor_score = 0;
     // Deriving from a templated base class shouldn't be enough to trigger
     // the ctor warning, but if you do *anything* else, it should.
     //
     // TODO(erg): This is motivated by templated base classes that don't have
     // any data members. Somehow detect when templated base classes have data
     // members and treat them differently.
     dtor_score += templated_base_classes * 9;
     // Instantiating a template is an insta-hit.
     dtor_score += templated_non_trivial_member * 10;
     // The fourth normal class member should trigger the warning.
     dtor_score += non_trivial_member * 3;
     int ctor_score = dtor_score;
     // You should be able to have 9 ints before we warn you.
     ctor_score += trivial_member;
     if (ctor_score >= 10) {
       if (!record->hasUserDeclaredConstructor()) {
         emitWarning(record_location,
                     "Complex class/struct needs an explicit out-of-line "
                     "constructor.");
       } else {
         // Iterate across all the constructors in this file and yell if we
         // find one that tries to be inline.
         for (CXXRecordDecl::ctor_iterator it = record->ctor_begin();
              it != record->ctor_end(); ++it) {
           if (it->hasInlineBody()) {
             if (it->isCopyConstructor() &&
                 !record->hasUserDeclaredCopyConstructor()) {
               emitWarning(record_location,
                           "Complex class/struct needs an explicit out-of-line "
                           "copy constructor.");
             } else {
               emitWarning(it->getInnerLocStart(),
                           "Complex constructor has an inlined body.");
             }
           }
         }
       }
     }
     // The destructor side is equivalent except that we don't check for
     // trivial members; 20 ints don't need a destructor.
     if (dtor_score >= 10 && !record->hasTrivialDestructor()) {
       if (!record->hasUserDeclaredDestructor()) {
         emitWarning(
             record_location,
             "Complex class/struct needs an explicit out-of-line "
             "destructor.");
       } else if (CXXDestructorDecl* dtor = record->getDestructor()) {
         if (dtor->hasInlineBody()) {
           emitWarning(dtor->getInnerLocStart(),
                       "Complex destructor has an inline body.");
         }
       }
     }
   }
   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 "{}". 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.");
         }
       }
     }
   }
   bool InTestingNamespace(const Decl* record) {
     return GetNamespace(record).find("testing") != std::string::npos;
   }
   bool IsMethodInBannedNamespace(const CXXMethodDecl* method) {
     if (InBannedNamespace(method))
       return true;
     for (CXXMethodDecl::method_iterator i = method->begin_overridden_methods();
          i != method->end_overridden_methods();
          ++i) {
       const CXXMethodDecl* overridden = *i;
       if (IsMethodInBannedNamespace(overridden))
         return true;
     }
     return false;
   }
   void CheckOverriddenMethod(const CXXMethodDecl* method) {
     if (!method->size_overridden_methods() || method->getAttr<OverrideAttr>())
       return;
     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.
   //
   // 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(SourceLocation record_location,
                            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, 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()) {
       case Type::Record: {
         // Simplifying; the whole class isn't trivial if the dtor is, but
         // we use this as a signal about complexity.
         if (TypeHasNonTrivialDtor(type))
           (*trivial_member)++;
         else
           (*non_trivial_member)++;
         break;
       }
       case Type::TemplateSpecialization: {
         TemplateName name =
             dyn_cast<TemplateSpecializationType>(type)->getTemplateName();
         bool whitelisted_template = false;
         // HACK: I'm at a loss about how to get the syntax checker to get
         // whether a template is exterened or not. For the first pass here,
         // just do retarded string comparisons.
         if (TemplateDecl* decl = name.getAsTemplateDecl()) {
           std::string base_name = decl->getNameAsString();
           if (base_name == "basic_string")
             whitelisted_template = true;
         }
         if (whitelisted_template)
           (*non_trivial_member)++;
         else
           (*templated_non_trivial_member)++;
         break;
       }
       case Type::Elaborated: {
         CountType(
             dyn_cast<ElaboratedType>(type)->getNamedType().getTypePtr(),
             trivial_member, non_trivial_member, templated_non_trivial_member);
         break;
       }
       case Type::Typedef: {
         while (const TypedefType* TT = dyn_cast<TypedefType>(type)) {
           type = TT->getDecl()->getUnderlyingType().getTypePtr();
         }
         CountType(type, trivial_member, non_trivial_member,
                   templated_non_trivial_member);
         break;
       }
       default: {
         // Stupid assumption: anything we see that isn't the above is one of
         // the 20 integer types.
         (*trivial_member)++;
         break;
       }
     }
   }
 };
 class FindBadConstructsAction : public PluginASTAction {
  public:
   FindBadConstructsAction()
       : check_refcounted_dtors_(true),
         check_virtuals_in_implementations_(true) {
   }
  protected:
   // Overridden from PluginASTAction:
   virtual ASTConsumer* CreateASTConsumer(CompilerInstance& instance,
                                          llvm::StringRef ref) {
     return new FindBadConstructsConsumer(
         instance, check_refcounted_dtors_, check_virtuals_in_implementations_);
   }
   virtual bool ParseArgs(const CompilerInstance& instance,
                          const std::vector<std::string>& args) {
     bool parsed = true;
     for (size_t i = 0; i < args.size() && parsed; ++i) {
       if (args[i] == "skip-refcounted-dtors") {
         check_refcounted_dtors_ = false;
       } else if (args[i] == "skip-virtuals-in-implementations") {
         check_virtuals_in_implementations_ = false;
       } else {
         parsed = false;
         llvm::errs() << "Unknown argument: " << args[i] << "\n";
       }
     }
     return parsed;
   }
  private:
   bool check_refcounted_dtors_;
   bool check_virtuals_in_implementations_;
 };
 }  // namespace
 static FrontendPluginRegistry::Add<FindBadConstructsAction>
 X("find-bad-constructs", "Finds bad C++ constructs");

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media/webrtc/trunk/tools/clang/plugins/FindBadConstructs.cpp@925c144e1f1f (annotated)

media/webrtc/trunk/tools/clang/plugins/FindBadConstructs.cpp