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 /* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */

 /* vim: set ts=8 sts=2 et sw=2 tw=80: */

 /* This Source Code Form is subject to the terms of the Mozilla Public

  * License, v. 2.0. If a copy of the MPL was not distributed with this

  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */

 /* Implementations of various class and method modifier attributes. */

 #ifndef mozilla_Attributes_h

 #define mozilla_Attributes_h

 #include "mozilla/Compiler.h"

 /*

  * MOZ_ALWAYS_INLINE is a macro which expands to tell the compiler that the

  * method decorated with it must be inlined, even if the compiler thinks

  * otherwise.  This is only a (much) stronger version of the inline hint:

  * compilers are not guaranteed to respect it (although they're much more likely

  * to do so).

  *

  * The MOZ_ALWAYS_INLINE_EVEN_DEBUG macro is yet stronger. It tells the

  * compiler to inline even in DEBUG builds. It should be used very rarely.

  */

 #if defined(_MSC_VER)

 #  define MOZ_ALWAYS_INLINE_EVEN_DEBUG     __forceinline

 #elif defined(__GNUC__)

 #  define MOZ_ALWAYS_INLINE_EVEN_DEBUG     __attribute__((always_inline)) inline

 #else

 #  define MOZ_ALWAYS_INLINE_EVEN_DEBUG     inline

 #endif

 #if !defined(DEBUG)

 #  define MOZ_ALWAYS_INLINE     MOZ_ALWAYS_INLINE_EVEN_DEBUG

 #elif defined(_MSC_VER) && !defined(__cplusplus)

 #  define MOZ_ALWAYS_INLINE     __inline

 #else

 #  define MOZ_ALWAYS_INLINE     inline

 #endif

 /*

  * g++ requires -std=c++0x or -std=gnu++0x to support C++11 functionality

  * without warnings (functionality used by the macros below).  These modes are

  * detectable by checking whether __GXX_EXPERIMENTAL_CXX0X__ is defined or, more

  * standardly, by checking whether __cplusplus has a C++11 or greater value.

  * Current versions of g++ do not correctly set __cplusplus, so we check both

  * for forward compatibility.

  */

 #if defined(__clang__)

    /*

     * Per Clang documentation, "Note that marketing version numbers should not

     * be used to check for language features, as different vendors use different

     * numbering schemes. Instead, use the feature checking macros."

     */

 #  ifndef __has_extension

 #    define __has_extension __has_feature /* compatibility, for older versions of clang */

 #  endif

 #  if __has_extension(cxx_constexpr)

 #    define MOZ_HAVE_CXX11_CONSTEXPR

 #  endif

 #  if __has_extension(cxx_explicit_conversions)

 #    define MOZ_HAVE_EXPLICIT_CONVERSION

 #  endif

 #  if __has_extension(cxx_deleted_functions)

 #    define MOZ_HAVE_CXX11_DELETE

 #  endif

 #  if __has_extension(cxx_override_control)

 #    define MOZ_HAVE_CXX11_OVERRIDE

 #    define MOZ_HAVE_CXX11_FINAL         final

 #  endif

 #  if __has_attribute(noinline)

 #    define MOZ_HAVE_NEVER_INLINE        __attribute__((noinline))

 #  endif

 #  if __has_attribute(noreturn)

 #    define MOZ_HAVE_NORETURN            __attribute__((noreturn))

 #  endif

 #elif defined(__GNUC__)

 #  if defined(__GXX_EXPERIMENTAL_CXX0X__) || __cplusplus >= 201103L

 #    if MOZ_GCC_VERSION_AT_LEAST(4, 7, 0)

 #      define MOZ_HAVE_CXX11_OVERRIDE

 #      define MOZ_HAVE_CXX11_FINAL       final

 #    endif

 #    if MOZ_GCC_VERSION_AT_LEAST(4, 6, 0)

 #      define MOZ_HAVE_CXX11_CONSTEXPR

 #    endif

 #    if MOZ_GCC_VERSION_AT_LEAST(4, 5, 0)

 #      define MOZ_HAVE_EXPLICIT_CONVERSION

 #    endif

 #    define MOZ_HAVE_CXX11_DELETE

 #  else

      /* __final is a non-C++11 GCC synonym for 'final', per GCC r176655. */

 #    if MOZ_GCC_VERSION_AT_LEAST(4, 7, 0)

 #      define MOZ_HAVE_CXX11_FINAL       __final

 #    endif

 #  endif

 #  define MOZ_HAVE_NEVER_INLINE          __attribute__((noinline))

 #  define MOZ_HAVE_NORETURN              __attribute__((noreturn))

 #elif defined(_MSC_VER)

 #  if _MSC_VER >= 1800

 #    define MOZ_HAVE_CXX11_DELETE

 #  endif

 #  if _MSC_VER >= 1700

 #    define MOZ_HAVE_CXX11_FINAL         final

 #  else

      /* MSVC <= 10 used to spell "final" as "sealed". */

 #    define MOZ_HAVE_CXX11_FINAL         sealed

 #  endif

 #  define MOZ_HAVE_CXX11_OVERRIDE

 #  define MOZ_HAVE_NEVER_INLINE          __declspec(noinline)

 #  define MOZ_HAVE_NORETURN              __declspec(noreturn)

 // Staying away from explicit conversion operators in MSVC for now, see

 // http://stackoverflow.com/questions/20498142/visual-studio-2013-explicit-keyword-bug

 #endif

 /*

  * The MOZ_CONSTEXPR specifier declares that a C++11 compiler can evaluate a

  * function at compile time. A constexpr function cannot examine any values

  * except its arguments and can have no side effects except its return value.

  * The MOZ_CONSTEXPR_VAR specifier tells a C++11 compiler that a variable's

  * value may be computed at compile time.  It should be prefered to just

  * marking variables as MOZ_CONSTEXPR because if the compiler does not support

  * constexpr it will fall back to making the variable const, and some compilers

  * do not accept variables being marked both const and constexpr.

  */

 #ifdef MOZ_HAVE_CXX11_CONSTEXPR

 #  define MOZ_CONSTEXPR         constexpr

 #  define MOZ_CONSTEXPR_VAR     constexpr

 #else

 #  define MOZ_CONSTEXPR         /* no support */

 #  define MOZ_CONSTEXPR_VAR     const

 #endif

 /*

  * MOZ_EXPLICIT_CONVERSION is a specifier on a type conversion

  * overloaded operator that declares that a C++11 compiler should restrict

  * this operator to allow only explicit type conversions, disallowing

  * implicit conversions.

  *

  * Example:

  *

  *   template<typename T>

  *   class Ptr

  *   {

  *      T* ptr;

  *      MOZ_EXPLICIT_CONVERSION operator bool() const {

  *        return ptr != nullptr;

  *      }

  *   };

  *

  */

 #ifdef MOZ_HAVE_EXPLICIT_CONVERSION

 #  define MOZ_EXPLICIT_CONVERSION explicit

 #else

 #  define MOZ_EXPLICIT_CONVERSION /* no support */

 #endif

 /*

  * MOZ_NEVER_INLINE is a macro which expands to tell the compiler that the

  * method decorated with it must never be inlined, even if the compiler would

  * otherwise choose to inline the method.  Compilers aren't absolutely

  * guaranteed to support this, but most do.

  */

 #if defined(MOZ_HAVE_NEVER_INLINE)

 #  define MOZ_NEVER_INLINE      MOZ_HAVE_NEVER_INLINE

 #else

 #  define MOZ_NEVER_INLINE      /* no support */

 #endif

 /*

  * MOZ_NORETURN, specified at the start of a function declaration, indicates

  * that the given function does not return.  (The function definition does not

  * need to be annotated.)

  *

  *   MOZ_NORETURN void abort(const char* msg);

  *

  * This modifier permits the compiler to optimize code assuming a call to such a

  * function will never return.  It also enables the compiler to avoid spurious

  * warnings about not initializing variables, or about any other seemingly-dodgy

  * operations performed after the function returns.

  *

  * This modifier does not affect the corresponding function's linking behavior.

  */

 #if defined(MOZ_HAVE_NORETURN)

 #  define MOZ_NORETURN          MOZ_HAVE_NORETURN

 #else

 #  define MOZ_NORETURN          /* no support */

 #endif

 /*

  * MOZ_ASAN_BLACKLIST is a macro to tell AddressSanitizer (a compile-time

  * instrumentation shipped with Clang and GCC) to not instrument the annotated

  * function. Furthermore, it will prevent the compiler from inlining the

  * function because inlining currently breaks the blacklisting mechanism of

  * AddressSanitizer.

  */

 #if defined(__has_feature)

 #  if __has_feature(address_sanitizer)

 #    define MOZ_HAVE_ASAN_BLACKLIST

 #  endif

 #elif defined(__GNUC__)

 #  if defined(__SANITIZE_ADDRESS__)

 #    define MOZ_HAVE_ASAN_BLACKLIST

 #  endif

 #endif

 #if defined(MOZ_HAVE_ASAN_BLACKLIST)

 #  define MOZ_ASAN_BLACKLIST MOZ_NEVER_INLINE __attribute__((no_sanitize_address))

 #else

 #  define MOZ_ASAN_BLACKLIST /* nothing */

 #endif

 /*

  * MOZ_TSAN_BLACKLIST is a macro to tell ThreadSanitizer (a compile-time

  * instrumentation shipped with Clang) to not instrument the annotated function.

  * Furthermore, it will prevent the compiler from inlining the function because

  * inlining currently breaks the blacklisting mechanism of ThreadSanitizer.

  */

 #if defined(__has_feature)

 #  if __has_feature(thread_sanitizer)

 #    define MOZ_TSAN_BLACKLIST MOZ_NEVER_INLINE __attribute__((no_sanitize_thread))

 #  else

 #    define MOZ_TSAN_BLACKLIST /* nothing */

 #  endif

 #else

 #  define MOZ_TSAN_BLACKLIST /* nothing */

 #endif

 #ifdef __cplusplus

 /*

  * MOZ_DELETE, specified immediately prior to the ';' terminating an undefined-

  * method declaration, attempts to delete that method from the corresponding

  * class.  An attempt to use the method will always produce an error *at compile

  * time* (instead of sometimes as late as link time) when this macro can be

  * implemented.  For example, you can use MOZ_DELETE to produce classes with no

  * implicit copy constructor or assignment operator:

  *

  *   struct NonCopyable

  *   {

  *     private:

  *       NonCopyable(const NonCopyable& other) MOZ_DELETE;

  *       void operator=(const NonCopyable& other) MOZ_DELETE;

  *   };

  *

  * If MOZ_DELETE can't be implemented for the current compiler, use of the

  * annotated method will still cause an error, but the error might occur at link

  * time in some cases rather than at compile time.

  *

  * MOZ_DELETE relies on C++11 functionality not universally implemented.  As a

  * backstop, method declarations using MOZ_DELETE should be private.

  */

 #if defined(MOZ_HAVE_CXX11_DELETE)

 #  define MOZ_DELETE            = delete

 #else

 #  define MOZ_DELETE            /* no support */

 #endif

 /*

  * MOZ_OVERRIDE explicitly indicates that a virtual member function in a class

  * overrides a member function of a base class, rather than potentially being a

  * new member function.  MOZ_OVERRIDE should be placed immediately before the

  * ';' terminating the member function's declaration, or before '= 0;' if the

  * member function is pure.  If the member function is defined in the class

  * definition, it should appear before the opening brace of the function body.

  *

  *   class Base

  *   {

  *     public:

  *       virtual void f() = 0;

  *   };

  *   class Derived1 : public Base

  *   {

  *     public:

  *       virtual void f() MOZ_OVERRIDE;

  *   };

  *   class Derived2 : public Base

  *   {

  *     public:

  *       virtual void f() MOZ_OVERRIDE = 0;

  *   };

  *   class Derived3 : public Base

  *   {

  *     public:

  *       virtual void f() MOZ_OVERRIDE { }

  *   };

  *

  * In compilers supporting C++11 override controls, MOZ_OVERRIDE *requires* that

  * the function marked with it override a member function of a base class: it

  * is a compile error if it does not.  Otherwise MOZ_OVERRIDE does not affect

  * semantics and merely documents the override relationship to the reader (but

  * of course must still be used correctly to not break C++11 compilers).

  */

 #if defined(MOZ_HAVE_CXX11_OVERRIDE)

 #  define MOZ_OVERRIDE          override

 #else

 #  define MOZ_OVERRIDE          /* no support */

 #endif

 /*

  * MOZ_FINAL indicates that some functionality cannot be overridden through

  * inheritance.  It can be used to annotate either classes/structs or virtual

  * member functions.

  *

  * To annotate a class/struct with MOZ_FINAL, place MOZ_FINAL immediately after

  * the name of the class, before the list of classes from which it derives (if

  * any) and before its opening brace.  MOZ_FINAL must not be used to annotate

  * unnamed classes or structs.  (With some compilers, and with C++11 proper, the

  * underlying expansion is ambiguous with specifying a class name.)

  *

  *   class Base MOZ_FINAL

  *   {

  *     public:

  *       Base();

  *       ~Base();

  *       virtual void f() { }

  *   };

  *   // This will be an error in some compilers:

  *   class Derived : public Base

  *   {

  *     public:

  *       ~Derived() { }

  *   };

  *

  * One particularly common reason to specify MOZ_FINAL upon a class is to tell

  * the compiler that it's not dangerous for it to have a non-virtual destructor

  * yet have one or more virtual functions, silencing the warning it might emit

  * in this case.  Suppose Base above weren't annotated with MOZ_FINAL.  Because

  * ~Base() is non-virtual, an attempt to delete a Derived* through a Base*

  * wouldn't call ~Derived(), so any cleanup ~Derived() might do wouldn't happen.

  * (Formally C++ says behavior is undefined, but compilers will likely just call

  * ~Base() and not ~Derived().)  Specifying MOZ_FINAL tells the compiler that

  * it's safe for the destructor to be non-virtual.

  *

  * In compilers implementing final controls, it is an error to inherit from a

  * class annotated with MOZ_FINAL.  In other compilers it serves only as

  * documentation.

  *

  * To annotate a virtual member function with MOZ_FINAL, place MOZ_FINAL

  * immediately before the ';' terminating the member function's declaration, or

  * before '= 0;' if the member function is pure.  If the member function is

  * defined in the class definition, it should appear before the opening brace of

  * the function body.  (This placement is identical to that for MOZ_OVERRIDE.

  * If both are used, they should appear in the order 'MOZ_FINAL MOZ_OVERRIDE'

  * for consistency.)

  *

  *   class Base

  *   {

  *     public:

  *       virtual void f() MOZ_FINAL;

  *   };

  *   class Derived

  *   {

  *     public:

  *       // This will be an error in some compilers:

  *       virtual void f();

  *   };

  *

  * In compilers implementing final controls, it is an error for a derived class

  * to override a method annotated with MOZ_FINAL.  In other compilers it serves

  * only as documentation.

  */

 #if defined(MOZ_HAVE_CXX11_FINAL)

 #  define MOZ_FINAL             MOZ_HAVE_CXX11_FINAL

 #else

 #  define MOZ_FINAL             /* no support */

 #endif

 /**

  * MOZ_WARN_UNUSED_RESULT tells the compiler to emit a warning if a function's

  * return value is not used by the caller.

  *

  * Place this attribute at the very beginning of a function definition. For

  * example, write

  *

  *   MOZ_WARN_UNUSED_RESULT int foo();

  *

  * or

  *

  *   MOZ_WARN_UNUSED_RESULT int foo() { return 42; }

  */

 #if defined(__GNUC__) || defined(__clang__)

 #  define MOZ_WARN_UNUSED_RESULT __attribute__ ((warn_unused_result))

 #else

 #  define MOZ_WARN_UNUSED_RESULT

 #endif

 /*

  * The following macros are attributes that support the static analysis plugin

  * included with Mozilla, and will be implemented (when such support is enabled)

  * as C++11 attributes. Since such attributes are legal pretty much everywhere

  * and have subtly different semantics depending on their placement, the

  * following is a guide on where to place the attributes.

  *

  * Attributes that apply to a struct or class precede the name of the class:

  * (Note that this is different from the placement of MOZ_FINAL for classes!)

  *

  *   class MOZ_CLASS_ATTRIBUTE SomeClass {};

  *

  * Attributes that apply to functions follow the parentheses and const

  * qualifiers but precede MOZ_FINAL, MOZ_OVERRIDE and the function body:

  *

  *   void DeclaredFunction() MOZ_FUNCTION_ATTRIBUTE;

  *   void SomeFunction() MOZ_FUNCTION_ATTRIBUTE {}

  *   void PureFunction() const MOZ_FUNCTION_ATTRIBUTE = 0;

  *   void OverriddenFunction() MOZ_FUNCTION_ATTIRBUTE MOZ_OVERRIDE;

  *

  * Attributes that apply to variables or parameters follow the variable's name:

  *

  *   int variable MOZ_VARIABLE_ATTRIBUTE;

  *

  * Attributes that apply to types follow the type name:

  *

  *   typedef int MOZ_TYPE_ATTRIBUTE MagicInt;

  *   int MOZ_TYPE_ATTRIBUTE someVariable;

  *   int * MOZ_TYPE_ATTRIBUTE magicPtrInt;

  *   int MOZ_TYPE_ATTRIBUTE * ptrToMagicInt;

  *

  * Attributes that apply to statements precede the statement:

  *

  *   MOZ_IF_ATTRIBUTE if (x == 0)

  *   MOZ_DO_ATTRIBUTE do { } while(0);

  *

  * Attributes that apply to labels precede the label:

  *

  *   MOZ_LABEL_ATTRIBUTE target:

  *     goto target;

  *   MOZ_CASE_ATTRIBUTE case 5:

  *   MOZ_DEFAULT_ATTRIBUTE default:

  *

  * The static analyses that are performed by the plugin are as follows:

  *

  * MOZ_MUST_OVERRIDE: Applies to all C++ member functions. All immediate

  *   subclasses must provide an exact override of this method; if a subclass

  *   does not override this method, the compiler will emit an error. This

  *   attribute is not limited to virtual methods, so if it is applied to a

  *   nonvirtual method and the subclass does not provide an equivalent

  *   definition, the compiler will emit an error.

  * MOZ_STACK_CLASS: Applies to all classes. Any class with this annotation is

  *   expected to live on the stack, so it is a compile-time error to use it, or

  *   an array of such objects, as a global or static variable, or as the type of

  *   a new expression (unless placement new is being used). If a member of

  *   another class uses this class, or if another class inherits from this

  *   class, then it is considered to be a stack class as well, although this

  *   attribute need not be provided in such cases.

  * MOZ_NONHEAP_CLASS: Applies to all classes. Any class with this annotation is

  *   expected to live on the stack or in static storage, so it is a compile-time

  *   error to use it, or an array of such objects, as the type of a new

  *   expression (unless placement new is being used). If a member of another

  *   class uses this class, or if another class inherits from this class, then

  *   it is considered to be a non-heap class as well, although this attribute

  *   need not be provided in such cases.

  * MOZ_HEAP_ALLOCATOR: Applies to any function. This indicates that the return

  *   value is allocated on the heap, and will as a result check such allocations

  *   during MOZ_STACK_CLASS and MOZ_NONHEAP_CLASS annotation checking.

  */

 #ifdef MOZ_CLANG_PLUGIN

 #  define MOZ_MUST_OVERRIDE __attribute__((annotate("moz_must_override")))

 #  define MOZ_STACK_CLASS __attribute__((annotate("moz_stack_class")))

 #  define MOZ_NONHEAP_CLASS __attribute__((annotate("moz_nonheap_class")))

 /*

  * It turns out that clang doesn't like void func() __attribute__ {} without a

  * warning, so use pragmas to disable the warning. This code won't work on GCC

  * anyways, so the warning is safe to ignore.

  */

 #  define MOZ_HEAP_ALLOCATOR \

     _Pragma("clang diagnostic push") \

     _Pragma("clang diagnostic ignored \"-Wgcc-compat\"") \

     __attribute__((annotate("moz_heap_allocator"))) \

     _Pragma("clang diagnostic pop")

 #else

 #  define MOZ_MUST_OVERRIDE /* nothing */

 #  define MOZ_STACK_CLASS /* nothing */

 #  define MOZ_NONHEAP_CLASS /* nothing */

 #  define MOZ_HEAP_ALLOCATOR /* nothing */

 #endif /* MOZ_CLANG_PLUGIN */

 /*

  * MOZ_THIS_IN_INITIALIZER_LIST is used to avoid a warning when we know that

  * it's safe to use 'this' in an initializer list.

  */

 #ifdef _MSC_VER

 #  define MOZ_THIS_IN_INITIALIZER_LIST() \

      __pragma(warning(push)) \

      __pragma(warning(disable:4355)) \

      this \

      __pragma(warning(pop))

 #else

 #  define MOZ_THIS_IN_INITIALIZER_LIST() this

 #endif

 #endif /* __cplusplus */

 #endif /* mozilla_Attributes_h */