/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */ /* 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_ /* * This header does not include any other headers so that it can be included by * code that is (only currently) mfbt-incompatible. */ /* * MOZ_INLINE is a macro which expands to tell the compiler that the method * decorated with it should be inlined. This macro is usable from C and C++ * code, even though C89 does not support the |inline| keyword. The compiler * may ignore this directive if it chooses. */ #if defined(__cplusplus) # define MOZ_INLINE inline #elif defined(_MSC_VER) # define MOZ_INLINE __inline #elif defined(__GNUC__) # define MOZ_INLINE __inline__ #else # define MOZ_INLINE inline #endif /* * 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 MOZ_INLINE hint: * compilers are not guaranteed to respect it (although they're much more likely * to do so). */ #if defined(DEBUG) # define MOZ_ALWAYS_INLINE MOZ_INLINE #elif defined(_MSC_VER) # define MOZ_ALWAYS_INLINE __forceinline #elif defined(__GNUC__) # define MOZ_ALWAYS_INLINE __attribute__((always_inline)) MOZ_INLINE #else # define MOZ_ALWAYS_INLINE MOZ_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_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_extension(cxx_strong_enums) # define MOZ_HAVE_CXX11_ENUM_TYPE # define MOZ_HAVE_CXX11_STRONG_ENUMS # 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 __GNUC__ > 4 # define MOZ_HAVE_CXX11_DELETE # define MOZ_HAVE_CXX11_OVERRIDE # define MOZ_HAVE_CXX11_FINAL final # elif __GNUC__ == 4 # if __GNUC_MINOR__ >= 7 # define MOZ_HAVE_CXX11_OVERRIDE # define MOZ_HAVE_CXX11_FINAL final # endif # define MOZ_HAVE_CXX11_DELETE # if __GNUC_MINOR__ >= 5 # define MOZ_HAVE_CXX11_ENUM_TYPE # define MOZ_HAVE_CXX11_STRONG_ENUMS # endif # endif # else /* __final is a non-C++11 GCC synonym for 'final', per GCC r176655. */ # if __GNUC__ > 4 # define MOZ_HAVE_CXX11_FINAL __final # elif __GNUC__ == 4 # if __GNUC_MINOR__ >= 7 # define MOZ_HAVE_CXX11_FINAL __final # endif # endif # endif # define MOZ_HAVE_NEVER_INLINE __attribute__((noinline)) # define MOZ_HAVE_NORETURN __attribute__((noreturn)) #elif defined(_MSC_VER) # if _MSC_VER >= 1400 # define MOZ_HAVE_CXX11_OVERRIDE /* MSVC currently spells "final" as "sealed". */ # define MOZ_HAVE_CXX11_FINAL sealed # define MOZ_HAVE_CXX11_ENUM_TYPE # endif # if _MSC_VER >= 1700 # define MOZ_HAVE_CXX11_STRONG_ENUMS # endif # define MOZ_HAVE_NEVER_INLINE __declspec(noinline) # define MOZ_HAVE_NORETURN __declspec(noreturn) #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) 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(MOZ_ASAN) # define MOZ_ASAN_BLACKLIST MOZ_NEVER_INLINE __attribute__((no_address_safety_analysis)) # else # define MOZ_ASAN_BLACKLIST #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_ENUM_TYPE specifies the underlying numeric type for an enum. It's * specified by placing MOZ_ENUM_TYPE(type) immediately after the enum name in * its declaration, and before the opening curly brace, like * * enum MyEnum MOZ_ENUM_TYPE(uint16_t) * { * A, * B = 7, * C * }; * * In supporting compilers, the macro will expand to ": uint16_t". The * compiler will allocate exactly two bytes for MyEnum, and will require all * enumerators to have values between 0 and 65535. (Thus specifying "B = * 100000" instead of "B = 7" would fail to compile.) In old compilers, the * macro expands to the empty string, and the underlying type is generally * undefined. */ #ifdef MOZ_HAVE_CXX11_ENUM_TYPE # define MOZ_ENUM_TYPE(type) : type #else # define MOZ_ENUM_TYPE(type) /* no support */ #endif /** * MOZ_BEGIN_ENUM_CLASS and MOZ_END_ENUM_CLASS provide access to the * strongly-typed enumeration feature of C++11 ("enum class"). If supported * by the compiler, an enum defined using these macros will not be implicitly * converted to any other type, and its enumerators will be scoped using the * enumeration name. Place MOZ_BEGIN_ENUM_CLASS(EnumName, type) in place of * "enum EnumName {", and MOZ_END_ENUM_CLASS(EnumName) in place of the closing * "};". For example, * * MOZ_BEGIN_ENUM_CLASS(Enum, int32_t) * A, B = 6 * MOZ_END_ENUM_CLASS(Enum) * * This will make "Enum::A" and "Enum::B" appear in the global scope, but "A" * and "B" will not. In compilers that support C++11 strongly-typed * enumerations, implicit conversions of Enum values to numeric types will * fail. In other compilers, Enum itself will actually be defined as a class, * and some implicit conversions will fail while others will succeed. * * The type argument specifies the underlying type for the enum where * supported, as with MOZ_ENUM_TYPE(). For simplicity, it is currently * mandatory. As with MOZ_ENUM_TYPE(), it will do nothing on compilers that do * not support it. * * Note that the workaround implemented here is not compatible with enums * nested inside a class. */ #if defined(MOZ_HAVE_CXX11_STRONG_ENUMS) /* All compilers that support strong enums also support an explicit * underlying type, so no extra check is needed */ # define MOZ_BEGIN_ENUM_CLASS(Name, type) enum class Name : type { # define MOZ_END_ENUM_CLASS(Name) }; #else /** * We need Name to both name a type, and scope the provided enumerator * names. Namespaces and classes both provide scoping, but namespaces * aren't types, so we need to use a class that wraps the enum values. We * have an implicit conversion from the inner enum type to the class, so * statements like * * Enum x = Enum::A; * * will still work. We need to define an implicit conversion from the class * to the inner enum as well, so that (for instance) switch statements will * work. This means that the class can be implicitly converted to a numeric * value as well via the enum type, since C++ allows an implicit * user-defined conversion followed by a standard conversion to still be * implicit. * * We have an explicit constructor from int defined, so that casts like * (Enum)7 will still work. We also have a zero-argument constructor with * no arguments, so declaration without initialization (like "Enum foo;") * will work. * * Additionally, we'll delete as many operators as possible for the inner * enum type, so statements like this will still fail: * * f(5 + Enum::B); // deleted operator+ * * But we can't prevent things like this, because C++ doesn't allow * overriding conversions or assignment operators for enums: * * int x = Enum::A; * int f() * { * return Enum::A; * } */ # define MOZ_BEGIN_ENUM_CLASS(Name, type) \ class Name \ { \ public: \ enum Enum MOZ_ENUM_TYPE(type) \ { # define MOZ_END_ENUM_CLASS(Name) \ }; \ Name() {} \ Name(Enum aEnum) : mEnum(aEnum) {} \ explicit Name(int num) : mEnum((Enum)num) {} \ operator Enum() const { return mEnum; } \ private: \ Enum mEnum; \ }; \ inline int operator+(const int&, const Name::Enum&) MOZ_DELETE; \ inline int operator+(const Name::Enum&, const int&) MOZ_DELETE; \ inline int operator-(const int&, const Name::Enum&) MOZ_DELETE; \ inline int operator-(const Name::Enum&, const int&) MOZ_DELETE; \ inline int operator*(const int&, const Name::Enum&) MOZ_DELETE; \ inline int operator*(const Name::Enum&, const int&) MOZ_DELETE; \ inline int operator/(const int&, const Name::Enum&) MOZ_DELETE; \ inline int operator/(const Name::Enum&, const int&) MOZ_DELETE; \ inline int operator%(const int&, const Name::Enum&) MOZ_DELETE; \ inline int operator%(const Name::Enum&, const int&) MOZ_DELETE; \ inline int operator+(const Name::Enum&) MOZ_DELETE; \ inline int operator-(const Name::Enum&) MOZ_DELETE; \ inline int& operator++(Name::Enum&) MOZ_DELETE; \ inline int operator++(Name::Enum&, int) MOZ_DELETE; \ inline int& operator--(Name::Enum&) MOZ_DELETE; \ inline int operator--(Name::Enum&, int) MOZ_DELETE; \ inline bool operator==(const int&, const Name::Enum&) MOZ_DELETE; \ inline bool operator==(const Name::Enum&, const int&) MOZ_DELETE; \ inline bool operator!=(const int&, const Name::Enum&) MOZ_DELETE; \ inline bool operator!=(const Name::Enum&, const int&) MOZ_DELETE; \ inline bool operator>(const int&, const Name::Enum&) MOZ_DELETE; \ inline bool operator>(const Name::Enum&, const int&) MOZ_DELETE; \ inline bool operator<(const int&, const Name::Enum&) MOZ_DELETE; \ inline bool operator<(const Name::Enum&, const int&) MOZ_DELETE; \ inline bool operator>=(const int&, const Name::Enum&) MOZ_DELETE; \ inline bool operator>=(const Name::Enum&, const int&) MOZ_DELETE; \ inline bool operator<=(const int&, const Name::Enum&) MOZ_DELETE; \ inline bool operator<=(const Name::Enum&, const int&) MOZ_DELETE; \ inline bool operator!(const Name::Enum&) MOZ_DELETE; \ inline bool operator&&(const bool&, const Name::Enum&) MOZ_DELETE; \ inline bool operator&&(const Name::Enum&, const bool&) MOZ_DELETE; \ inline bool operator||(const bool&, const Name::Enum&) MOZ_DELETE; \ inline bool operator||(const Name::Enum&, const bool&) MOZ_DELETE; \ inline int operator~(const Name::Enum&) MOZ_DELETE; \ inline int operator&(const int&, const Name::Enum&) MOZ_DELETE; \ inline int operator&(const Name::Enum&, const int&) MOZ_DELETE; \ inline int operator|(const int&, const Name::Enum&) MOZ_DELETE; \ inline int operator|(const Name::Enum&, const int&) MOZ_DELETE; \ inline int operator^(const int&, const Name::Enum&) MOZ_DELETE; \ inline int operator^(const Name::Enum&, const int&) MOZ_DELETE; \ inline int operator<<(const int&, const Name::Enum&) MOZ_DELETE; \ inline int operator<<(const Name::Enum&, const int&) MOZ_DELETE; \ inline int operator>>(const int&, const Name::Enum&) MOZ_DELETE; \ inline int operator>>(const Name::Enum&, const int&) MOZ_DELETE; \ inline int& operator+=(int&, const Name::Enum&) MOZ_DELETE; \ inline int& operator-=(int&, const Name::Enum&) MOZ_DELETE; \ inline int& operator*=(int&, const Name::Enum&) MOZ_DELETE; \ inline int& operator/=(int&, const Name::Enum&) MOZ_DELETE; \ inline int& operator%=(int&, const Name::Enum&) MOZ_DELETE; \ inline int& operator&=(int&, const Name::Enum&) MOZ_DELETE; \ inline int& operator|=(int&, const Name::Enum&) MOZ_DELETE; \ inline int& operator^=(int&, const Name::Enum&) MOZ_DELETE; \ inline int& operator<<=(int&, const Name::Enum&) MOZ_DELETE; \ inline int& operator>>=(int&, const Name::Enum&) MOZ_DELETE; #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 #endif /* __cplusplus */ #endif /* mozilla_Attributes_h_ */