зеркало из https://github.com/mozilla/gecko-dev.git
453 строки
18 KiB
C
453 строки
18 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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#if defined(_MSC_VER)
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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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* Even though some versions of MSVC support explicit conversion operators, we
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* don't indicate support for them here, due to
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* http://stackoverflow.com/questions/20498142/visual-studio-2013-explicit-keyword-bug
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*/
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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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# ifdef __clang__
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/* clang-cl probably supports constexpr and explicit conversions. */
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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_explicit_conversions)
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# define MOZ_HAVE_EXPLICIT_CONVERSION
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# endif
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# endif
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#elif 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_explicit_conversions)
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# define MOZ_HAVE_EXPLICIT_CONVERSION
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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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# define MOZ_HAVE_CXX11_CONSTEXPR
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# if MOZ_GCC_VERSION_AT_LEAST(4, 8, 0)
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# define MOZ_HAVE_CXX11_CONSTEXPR_IN_TEMPLATES
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# endif
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# define MOZ_HAVE_EXPLICIT_CONVERSION
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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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#endif
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/*
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* When built with clang analyzer (a.k.a scan-build), define MOZ_HAVE_NORETURN
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* to mark some false positives
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*/
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#ifdef __clang_analyzer__
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# if __has_extension(attribute_analyzer_noreturn)
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# define MOZ_HAVE_ANALYZER_NORETURN __attribute__((analyzer_noreturn))
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# endif
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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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# ifdef MOZ_HAVE_CXX11_CONSTEXPR_IN_TEMPLATES
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# define MOZ_CONSTEXPR_TMPL constexpr
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# else
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# define MOZ_CONSTEXPR_TMPL
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# endif
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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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# define MOZ_CONSTEXPR_TMPL
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#endif
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/*
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* MOZ_EXPLICIT_CONVERSION is a specifier on a type conversion
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* overloaded operator that declares that a C++11 compiler should restrict
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* this operator to allow only explicit type conversions, disallowing
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* implicit conversions.
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*
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* Example:
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*
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* template<typename T>
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* class Ptr
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* {
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* T* mPtr;
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* MOZ_EXPLICIT_CONVERSION operator bool() const
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* {
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* return mPtr != nullptr;
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* }
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* };
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*
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*/
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#ifdef MOZ_HAVE_EXPLICIT_CONVERSION
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# define MOZ_EXPLICIT_CONVERSION explicit
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#else
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# define MOZ_EXPLICIT_CONVERSION /* no support */
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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_COLD tells the compiler that a function is "cold", meaning infrequently
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* executed. This may lead it to optimize for size more aggressively than speed,
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* or to allocate the body of the function in a distant part of the text segment
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* to help keep it from taking up unnecessary icache when it isn't in use.
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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_COLD int foo();
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*
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* or
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*
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* MOZ_COLD int foo() { return 42; }
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*/
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#if defined(__GNUC__) || defined(__clang__)
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# define MOZ_COLD __attribute__ ((cold))
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#else
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# define MOZ_COLD
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#endif
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/**
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* MOZ_NONNULL tells the compiler that some of the arguments to a function are
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* known to be non-null. The arguments are a list of 1-based argument indexes
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* identifying arguments which are known to be non-null.
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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_NONNULL(1, 2) int foo(char *p, char *q);
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*/
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#if defined(__GNUC__) || defined(__clang__)
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# define MOZ_NONNULL(...) __attribute__ ((nonnull(__VA_ARGS__)))
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#else
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# define MOZ_NONNULL(...)
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#endif
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/*
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* MOZ_PRETEND_NORETURN_FOR_STATIC_ANALYSIS, specified at the end of a function
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* declaration, indicates that for the purposes of static analysis, this
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* function does not return. (The function definition does not need to be
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* annotated.)
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*
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* MOZ_ReportCrash(const char* s, const char* file, int ln)
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* MOZ_PRETEND_NORETURN_FOR_STATIC_ANALYSIS
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*
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* Some static analyzers, like scan-build from clang, can use this information
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* to eliminate false positives. From the upstream documentation of scan-build:
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* "This attribute is useful for annotating assertion handlers that actually
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* can return, but for the purpose of using the analyzer we want to pretend
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* that such functions do not return."
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*
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*/
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#if defined(MOZ_HAVE_ANALYZER_NORETURN)
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# define MOZ_PRETEND_NORETURN_FOR_STATIC_ANALYSIS MOZ_HAVE_ANALYZER_NORETURN
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#else
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# define MOZ_PRETEND_NORETURN_FOR_STATIC_ANALYSIS /* 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_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 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 final, 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 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_ONLY_USED_TO_AVOID_STATIC_CONSTRUCTORS: Applies to all classes that are
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* intended to prevent introducing static initializers. This attribute
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* currently makes it a compile-time error to instantiate these classes
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* anywhere other than at the global scope, or as a static member of a class.
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* MOZ_TRIVIAL_CTOR_DTOR: Applies to all classes that must have both a trivial
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* constructor and a trivial destructor. Setting this attribute on a class
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* makes it a compile-time error for that class to get a non-trivial
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* constructor or destructor for any reason.
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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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* MOZ_IMPLICIT: Applies to constructors. Implicit conversion constructors
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* are disallowed by default unless they are marked as MOZ_IMPLICIT. This
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* attribute must be used for constructors which intend to provide implicit
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* conversions.
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* MOZ_NO_ARITHMETIC_EXPR_IN_ARGUMENT: Applies to functions. Makes it a compile
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* time error to pass arithmetic expressions on variables to the function.
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* MOZ_OWNING_REF: Applies to declarations of pointer types. This attribute
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* tells the compiler that the raw pointer is a strong reference, and that
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* property is somehow enforced by the code. This can make the compiler
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* ignore these pointers when validating the usage of pointers otherwise.
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* MOZ_NON_OWNING_REF: Applies to declarations of pointer types. This attribute
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* tells the compiler that the raw pointer is a weak reference, and that
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* property is somehow enforced by the code. This can make the compiler
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* ignore these pointers when validating the usage of pointers otherwise.
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* MOZ_UNSAFE_REF: Applies to declarations of pointer types. This attribute
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* should be used for non-owning references that can be unsafe, and their
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* safety needs to be validated through code inspection. The string argument
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* passed to this macro documents the safety conditions.
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* MOZ_NO_ADDREF_RELEASE_ON_RETURN: Applies to function declarations. Makes it
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* a compile time error to call AddRef or Release on the return value of a
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* function. This is intended to be used with operator->() of our smart
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* pointer classes to ensure that the refcount of an object wrapped in a
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* smart pointer is not manipulated directly.
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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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# define MOZ_TRIVIAL_CTOR_DTOR __attribute__((annotate("moz_trivial_ctor_dtor")))
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# ifdef DEBUG
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/* in debug builds, these classes do have non-trivial constructors. */
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# define MOZ_ONLY_USED_TO_AVOID_STATIC_CONSTRUCTORS __attribute__((annotate("moz_global_class")))
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# else
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# define MOZ_ONLY_USED_TO_AVOID_STATIC_CONSTRUCTORS __attribute__((annotate("moz_global_class"))) \
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MOZ_TRIVIAL_CTOR_DTOR
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# endif
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# define MOZ_IMPLICIT __attribute__((annotate("moz_implicit")))
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# define MOZ_NO_ARITHMETIC_EXPR_IN_ARGUMENT __attribute__((annotate("moz_no_arith_expr_in_arg")))
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# define MOZ_OWNING_REF __attribute__((annotate("moz_strong_ref")))
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# define MOZ_NON_OWNING_REF __attribute__((annotate("moz_weak_ref")))
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# define MOZ_UNSAFE_REF(reason) __attribute__((annotate("moz_strong_ref")))
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# define MOZ_NO_ADDREF_RELEASE_ON_RETURN __attribute__((annotate("moz_no_addref_release_on_return")))
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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_TRIVIAL_CTOR_DTOR /* nothing */
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# define MOZ_ONLY_USED_TO_AVOID_STATIC_CONSTRUCTORS /* nothing */
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# define MOZ_IMPLICIT /* nothing */
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# define MOZ_NO_ARITHMETIC_EXPR_IN_ARGUMENT /* nothing */
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# define MOZ_HEAP_ALLOCATOR /* nothing */
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# define MOZ_OWNING_REF /* nothing */
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# define MOZ_NON_OWNING_REF /* nothing */
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# define MOZ_UNSAFE_REF(reason) /* nothing */
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# define MOZ_NO_ADDREF_RELEASE_ON_RETURN /* nothing */
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#endif /* MOZ_CLANG_PLUGIN */
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#endif /* __cplusplus */
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#endif /* mozilla_Attributes_h */
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