зеркало из https://github.com/mozilla/gecko-dev.git
461 строка
17 KiB
C
461 строка
17 KiB
C
/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
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/* vim: set ts=8 sts=2 et sw=2 tw=80: */
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/* This Source Code Form is subject to the terms of the Mozilla Public
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* License, v. 2.0. If a copy of the MPL was not distributed with this
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* file, You can obtain one at http://mozilla.org/MPL/2.0/. */
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/* Implementations of various class and method modifier attributes. */
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#ifndef mozilla_Attributes_h
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#define mozilla_Attributes_h
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#include "mozilla/Compiler.h"
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/*
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* MOZ_ALWAYS_INLINE is a macro which expands to tell the compiler that the
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* method decorated with it must be inlined, even if the compiler thinks
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* otherwise. This is only a (much) stronger version of the inline hint:
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* compilers are not guaranteed to respect it (although they're much more likely
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* to do so).
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*
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* The MOZ_ALWAYS_INLINE_EVEN_DEBUG macro is yet stronger. It tells the
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* compiler to inline even in DEBUG builds. It should be used very rarely.
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*/
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#if defined(_MSC_VER)
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# define MOZ_ALWAYS_INLINE_EVEN_DEBUG __forceinline
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#elif defined(__GNUC__)
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# define MOZ_ALWAYS_INLINE_EVEN_DEBUG __attribute__((always_inline)) inline
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#else
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# define MOZ_ALWAYS_INLINE_EVEN_DEBUG inline
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#endif
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#if !defined(DEBUG)
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# define MOZ_ALWAYS_INLINE MOZ_ALWAYS_INLINE_EVEN_DEBUG
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#elif defined(_MSC_VER) && !defined(__cplusplus)
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# define MOZ_ALWAYS_INLINE __inline
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#else
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# define MOZ_ALWAYS_INLINE inline
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#endif
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/*
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* g++ requires -std=c++0x or -std=gnu++0x to support C++11 functionality
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* without warnings (functionality used by the macros below). These modes are
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* detectable by checking whether __GXX_EXPERIMENTAL_CXX0X__ is defined or, more
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* standardly, by checking whether __cplusplus has a C++11 or greater value.
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* Current versions of g++ do not correctly set __cplusplus, so we check both
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* for forward compatibility.
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*/
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#if defined(__clang__)
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/*
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* Per Clang documentation, "Note that marketing version numbers should not
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* be used to check for language features, as different vendors use different
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* numbering schemes. Instead, use the feature checking macros."
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*/
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# ifndef __has_extension
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# define __has_extension __has_feature /* compatibility, for older versions of clang */
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# endif
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# if __has_extension(cxx_constexpr)
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# define MOZ_HAVE_CXX11_CONSTEXPR
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# endif
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# if __has_extension(cxx_deleted_functions)
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# define MOZ_HAVE_CXX11_DELETE
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# endif
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# if __has_extension(cxx_override_control)
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# define MOZ_HAVE_CXX11_OVERRIDE
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# define MOZ_HAVE_CXX11_FINAL final
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# endif
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# if __has_attribute(noinline)
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# define MOZ_HAVE_NEVER_INLINE __attribute__((noinline))
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# endif
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# if __has_attribute(noreturn)
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# define MOZ_HAVE_NORETURN __attribute__((noreturn))
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# endif
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#elif defined(__GNUC__)
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# if defined(__GXX_EXPERIMENTAL_CXX0X__) || __cplusplus >= 201103L
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# if MOZ_GCC_VERSION_AT_LEAST(4, 7, 0)
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# define MOZ_HAVE_CXX11_OVERRIDE
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# define MOZ_HAVE_CXX11_FINAL final
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# endif
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# if MOZ_GCC_VERSION_AT_LEAST(4, 6, 0)
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# define MOZ_HAVE_CXX11_CONSTEXPR
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# endif
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# define MOZ_HAVE_CXX11_DELETE
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# else
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/* __final is a non-C++11 GCC synonym for 'final', per GCC r176655. */
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# if MOZ_GCC_VERSION_AT_LEAST(4, 7, 0)
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# define MOZ_HAVE_CXX11_FINAL __final
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# endif
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# endif
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# define MOZ_HAVE_NEVER_INLINE __attribute__((noinline))
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# define MOZ_HAVE_NORETURN __attribute__((noreturn))
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#elif defined(_MSC_VER)
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# if _MSC_VER >= 1800
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# define MOZ_HAVE_CXX11_DELETE
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# endif
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# if _MSC_VER >= 1700
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# define MOZ_HAVE_CXX11_FINAL final
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# else
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/* MSVC <= 10 used to spell "final" as "sealed". */
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# define MOZ_HAVE_CXX11_FINAL sealed
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# endif
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# define MOZ_HAVE_CXX11_OVERRIDE
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# define MOZ_HAVE_NEVER_INLINE __declspec(noinline)
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# define MOZ_HAVE_NORETURN __declspec(noreturn)
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#endif
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/*
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* The MOZ_CONSTEXPR specifier declares that a C++11 compiler can evaluate a
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* function at compile time. A constexpr function cannot examine any values
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* except its arguments and can have no side effects except its return value.
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* The MOZ_CONSTEXPR_VAR specifier tells a C++11 compiler that a variable's
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* value may be computed at compile time. It should be prefered to just
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* marking variables as MOZ_CONSTEXPR because if the compiler does not support
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* constexpr it will fall back to making the variable const, and some compilers
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* do not accept variables being marked both const and constexpr.
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*/
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#ifdef MOZ_HAVE_CXX11_CONSTEXPR
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# define MOZ_CONSTEXPR constexpr
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# define MOZ_CONSTEXPR_VAR constexpr
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#else
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# define MOZ_CONSTEXPR /* no support */
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# define MOZ_CONSTEXPR_VAR const
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#endif
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/*
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* MOZ_NEVER_INLINE is a macro which expands to tell the compiler that the
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* method decorated with it must never be inlined, even if the compiler would
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* otherwise choose to inline the method. Compilers aren't absolutely
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* guaranteed to support this, but most do.
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*/
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#if defined(MOZ_HAVE_NEVER_INLINE)
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# define MOZ_NEVER_INLINE MOZ_HAVE_NEVER_INLINE
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#else
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# define MOZ_NEVER_INLINE /* no support */
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#endif
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/*
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* MOZ_NORETURN, specified at the start of a function declaration, indicates
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* that the given function does not return. (The function definition does not
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* need to be annotated.)
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*
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* MOZ_NORETURN void abort(const char* msg);
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*
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* This modifier permits the compiler to optimize code assuming a call to such a
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* function will never return. It also enables the compiler to avoid spurious
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* warnings about not initializing variables, or about any other seemingly-dodgy
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* operations performed after the function returns.
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*
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* This modifier does not affect the corresponding function's linking behavior.
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*/
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#if defined(MOZ_HAVE_NORETURN)
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# define MOZ_NORETURN MOZ_HAVE_NORETURN
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#else
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# define MOZ_NORETURN /* no support */
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#endif
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/*
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* MOZ_ASAN_BLACKLIST is a macro to tell AddressSanitizer (a compile-time
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* instrumentation shipped with Clang and GCC) to not instrument the annotated
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* function. Furthermore, it will prevent the compiler from inlining the
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* function because inlining currently breaks the blacklisting mechanism of
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* AddressSanitizer.
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*/
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#if defined(__has_feature)
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# if __has_feature(address_sanitizer)
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# define MOZ_HAVE_ASAN_BLACKLIST
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# endif
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#elif defined(__GNUC__)
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# if defined(__SANITIZE_ADDRESS__)
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# define MOZ_HAVE_ASAN_BLACKLIST
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# endif
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#endif
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#if defined(MOZ_HAVE_ASAN_BLACKLIST)
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# define MOZ_ASAN_BLACKLIST MOZ_NEVER_INLINE __attribute__((no_sanitize_address))
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#else
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# define MOZ_ASAN_BLACKLIST /* nothing */
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#endif
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/*
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* MOZ_TSAN_BLACKLIST is a macro to tell ThreadSanitizer (a compile-time
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* instrumentation shipped with Clang) to not instrument the annotated function.
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* Furthermore, it will prevent the compiler from inlining the function because
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* inlining currently breaks the blacklisting mechanism of ThreadSanitizer.
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*/
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#if defined(__has_feature)
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# if __has_feature(thread_sanitizer)
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# define MOZ_TSAN_BLACKLIST MOZ_NEVER_INLINE __attribute__((no_sanitize_thread))
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# else
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# define MOZ_TSAN_BLACKLIST /* nothing */
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# endif
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#else
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# define MOZ_TSAN_BLACKLIST /* nothing */
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#endif
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#ifdef __cplusplus
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/*
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* MOZ_DELETE, specified immediately prior to the ';' terminating an undefined-
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* method declaration, attempts to delete that method from the corresponding
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* class. An attempt to use the method will always produce an error *at compile
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* time* (instead of sometimes as late as link time) when this macro can be
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* implemented. For example, you can use MOZ_DELETE to produce classes with no
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* implicit copy constructor or assignment operator:
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*
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* struct NonCopyable
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* {
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* private:
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* NonCopyable(const NonCopyable& other) MOZ_DELETE;
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* void operator=(const NonCopyable& other) MOZ_DELETE;
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* };
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*
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* If MOZ_DELETE can't be implemented for the current compiler, use of the
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* annotated method will still cause an error, but the error might occur at link
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* time in some cases rather than at compile time.
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*
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* MOZ_DELETE relies on C++11 functionality not universally implemented. As a
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* backstop, method declarations using MOZ_DELETE should be private.
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*/
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#if defined(MOZ_HAVE_CXX11_DELETE)
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# define MOZ_DELETE = delete
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#else
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# define MOZ_DELETE /* no support */
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#endif
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/*
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* MOZ_OVERRIDE explicitly indicates that a virtual member function in a class
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* overrides a member function of a base class, rather than potentially being a
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* new member function. MOZ_OVERRIDE should be placed immediately before the
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* ';' terminating the member function's declaration, or before '= 0;' if the
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* member function is pure. If the member function is defined in the class
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* definition, it should appear before the opening brace of the function body.
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*
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* class Base
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* {
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* public:
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* virtual void f() = 0;
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* };
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* class Derived1 : public Base
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* {
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* public:
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* virtual void f() MOZ_OVERRIDE;
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* };
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* class Derived2 : public Base
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* {
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* public:
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* virtual void f() MOZ_OVERRIDE = 0;
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* };
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* class Derived3 : public Base
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* {
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* public:
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* virtual void f() MOZ_OVERRIDE { }
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* };
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*
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* In compilers supporting C++11 override controls, MOZ_OVERRIDE *requires* that
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* the function marked with it override a member function of a base class: it
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* is a compile error if it does not. Otherwise MOZ_OVERRIDE does not affect
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* semantics and merely documents the override relationship to the reader (but
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* of course must still be used correctly to not break C++11 compilers).
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*/
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#if defined(MOZ_HAVE_CXX11_OVERRIDE)
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# define MOZ_OVERRIDE override
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#else
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# define MOZ_OVERRIDE /* no support */
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#endif
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/*
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* MOZ_FINAL indicates that some functionality cannot be overridden through
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* inheritance. It can be used to annotate either classes/structs or virtual
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* member functions.
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*
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* To annotate a class/struct with MOZ_FINAL, place MOZ_FINAL immediately after
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* the name of the class, before the list of classes from which it derives (if
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* any) and before its opening brace. MOZ_FINAL must not be used to annotate
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* unnamed classes or structs. (With some compilers, and with C++11 proper, the
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* underlying expansion is ambiguous with specifying a class name.)
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*
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* class Base MOZ_FINAL
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* {
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* public:
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* Base();
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* ~Base();
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* virtual void f() { }
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* };
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* // This will be an error in some compilers:
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* class Derived : public Base
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* {
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* public:
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* ~Derived() { }
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* };
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*
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* One particularly common reason to specify MOZ_FINAL upon a class is to tell
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* the compiler that it's not dangerous for it to have a non-virtual destructor
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* yet have one or more virtual functions, silencing the warning it might emit
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* in this case. Suppose Base above weren't annotated with MOZ_FINAL. Because
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* ~Base() is non-virtual, an attempt to delete a Derived* through a Base*
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* wouldn't call ~Derived(), so any cleanup ~Derived() might do wouldn't happen.
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* (Formally C++ says behavior is undefined, but compilers will likely just call
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* ~Base() and not ~Derived().) Specifying MOZ_FINAL tells the compiler that
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* it's safe for the destructor to be non-virtual.
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*
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* In compilers implementing final controls, it is an error to inherit from a
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* class annotated with MOZ_FINAL. In other compilers it serves only as
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* documentation.
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*
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* To annotate a virtual member function with MOZ_FINAL, place MOZ_FINAL
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* immediately before the ';' terminating the member function's declaration, or
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* before '= 0;' if the member function is pure. If the member function is
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* defined in the class definition, it should appear before the opening brace of
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* the function body. (This placement is identical to that for MOZ_OVERRIDE.
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* If both are used, they should appear in the order 'MOZ_FINAL MOZ_OVERRIDE'
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* for consistency.)
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*
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* class Base
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* {
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* public:
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* virtual void f() MOZ_FINAL;
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* };
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* class Derived
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* {
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* public:
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* // This will be an error in some compilers:
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* virtual void f();
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* };
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*
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* In compilers implementing final controls, it is an error for a derived class
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* to override a method annotated with MOZ_FINAL. In other compilers it serves
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* only as documentation.
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*/
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#if defined(MOZ_HAVE_CXX11_FINAL)
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# define MOZ_FINAL MOZ_HAVE_CXX11_FINAL
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#else
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# define MOZ_FINAL /* no support */
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#endif
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/**
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* MOZ_WARN_UNUSED_RESULT tells the compiler to emit a warning if a function's
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* return value is not used by the caller.
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*
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* Place this attribute at the very beginning of a function definition. For
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* example, write
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*
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* MOZ_WARN_UNUSED_RESULT int foo();
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*
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* or
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*
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* MOZ_WARN_UNUSED_RESULT int foo() { return 42; }
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*/
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#if defined(__GNUC__) || defined(__clang__)
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# define MOZ_WARN_UNUSED_RESULT __attribute__ ((warn_unused_result))
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#else
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# define MOZ_WARN_UNUSED_RESULT
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#endif
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/*
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* The following macros are attributes that support the static analysis plugin
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* included with Mozilla, and will be implemented (when such support is enabled)
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* as C++11 attributes. Since such attributes are legal pretty much everywhere
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* and have subtly different semantics depending on their placement, the
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* following is a guide on where to place the attributes.
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*
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* Attributes that apply to a struct or class precede the name of the class:
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* (Note that this is different from the placement of MOZ_FINAL for classes!)
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*
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* class MOZ_CLASS_ATTRIBUTE SomeClass {};
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*
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* Attributes that apply to functions follow the parentheses and const
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* qualifiers but precede MOZ_FINAL, MOZ_OVERRIDE and the function body:
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*
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* void DeclaredFunction() MOZ_FUNCTION_ATTRIBUTE;
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* void SomeFunction() MOZ_FUNCTION_ATTRIBUTE {}
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* void PureFunction() const MOZ_FUNCTION_ATTRIBUTE = 0;
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* void OverriddenFunction() MOZ_FUNCTION_ATTIRBUTE MOZ_OVERRIDE;
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*
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* Attributes that apply to variables or parameters follow the variable's name:
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*
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* int variable MOZ_VARIABLE_ATTRIBUTE;
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*
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* Attributes that apply to types follow the type name:
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*
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* typedef int MOZ_TYPE_ATTRIBUTE MagicInt;
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* int MOZ_TYPE_ATTRIBUTE someVariable;
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* int * MOZ_TYPE_ATTRIBUTE magicPtrInt;
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* int MOZ_TYPE_ATTRIBUTE * ptrToMagicInt;
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*
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* Attributes that apply to statements precede the statement:
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*
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* MOZ_IF_ATTRIBUTE if (x == 0)
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* MOZ_DO_ATTRIBUTE do { } while(0);
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*
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* Attributes that apply to labels precede the label:
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*
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* MOZ_LABEL_ATTRIBUTE target:
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* goto target;
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* MOZ_CASE_ATTRIBUTE case 5:
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* MOZ_DEFAULT_ATTRIBUTE default:
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*
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* The static analyses that are performed by the plugin are as follows:
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*
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* MOZ_MUST_OVERRIDE: Applies to all C++ member functions. All immediate
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* subclasses must provide an exact override of this method; if a subclass
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* does not override this method, the compiler will emit an error. This
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* attribute is not limited to virtual methods, so if it is applied to a
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* nonvirtual method and the subclass does not provide an equivalent
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* definition, the compiler will emit an error.
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* MOZ_STACK_CLASS: Applies to all classes. Any class with this annotation is
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* expected to live on the stack, so it is a compile-time error to use it, or
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* an array of such objects, as a global or static variable, or as the type of
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* a new expression (unless placement new is being used). If a member of
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* another class uses this class, or if another class inherits from this
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* class, then it is considered to be a stack class as well, although this
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* attribute need not be provided in such cases.
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* MOZ_NONHEAP_CLASS: Applies to all classes. Any class with this annotation is
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* expected to live on the stack or in static storage, so it is a compile-time
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* error to use it, or an array of such objects, as the type of a new
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* expression (unless placement new is being used). If a member of another
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* class uses this class, or if another class inherits from this class, then
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* it is considered to be a non-heap class as well, although this attribute
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* need not be provided in such cases.
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* MOZ_HEAP_ALLOCATOR: Applies to any function. This indicates that the return
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* value is allocated on the heap, and will as a result check such allocations
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* during MOZ_STACK_CLASS and MOZ_NONHEAP_CLASS annotation checking.
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*/
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#ifdef MOZ_CLANG_PLUGIN
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# define MOZ_MUST_OVERRIDE __attribute__((annotate("moz_must_override")))
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# define MOZ_STACK_CLASS __attribute__((annotate("moz_stack_class")))
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# define MOZ_NONHEAP_CLASS __attribute__((annotate("moz_nonheap_class")))
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/*
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* It turns out that clang doesn't like void func() __attribute__ {} without a
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* warning, so use pragmas to disable the warning. This code won't work on GCC
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* anyways, so the warning is safe to ignore.
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*/
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# define MOZ_HEAP_ALLOCATOR \
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_Pragma("clang diagnostic push") \
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_Pragma("clang diagnostic ignored \"-Wgcc-compat\"") \
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__attribute__((annotate("moz_heap_allocator"))) \
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_Pragma("clang diagnostic pop")
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#else
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# define MOZ_MUST_OVERRIDE /* nothing */
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# define MOZ_STACK_CLASS /* nothing */
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# define MOZ_NONHEAP_CLASS /* nothing */
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# define MOZ_HEAP_ALLOCATOR /* nothing */
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#endif /* MOZ_CLANG_PLUGIN */
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/*
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* MOZ_THIS_IN_INITIALIZER_LIST is used to avoid a warning when we know that
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* it's safe to use 'this' in an initializer list.
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*/
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#ifdef _MSC_VER
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# define MOZ_THIS_IN_INITIALIZER_LIST() \
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__pragma(warning(push)) \
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__pragma(warning(disable:4355)) \
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this \
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__pragma(warning(pop))
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#else
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# define MOZ_THIS_IN_INITIALIZER_LIST() this
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#endif
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#endif /* __cplusplus */
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#endif /* mozilla_Attributes_h */
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