mfbt/Attributes.h

   1 /* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
   2 /* vim: set ts=8 sts=2 et sw=2 tw=80: */
   3 /* This Source Code Form is subject to the terms of the Mozilla Public
   4  * License, v. 2.0. If a copy of the MPL was not distributed with this
   5  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
   6
   7 /* Implementations of various class and method modifier attributes. */
   8
   9 #ifndef mozilla_Attributes_h
  10 #define mozilla_Attributes_h
  11
  12 #include "mozilla/Compiler.h"
  13
  14 /*
  15  * MOZ_ALWAYS_INLINE is a macro which expands to tell the compiler that the
  16  * method decorated with it must be inlined, even if the compiler thinks
  17  * otherwise.  This is only a (much) stronger version of the inline hint:
  18  * compilers are not guaranteed to respect it (although they're much more likely
  19  * to do so).
  20  *
  21  * The MOZ_ALWAYS_INLINE_EVEN_DEBUG macro is yet stronger. It tells the
  22  * compiler to inline even in DEBUG builds. It should be used very rarely.
  23  */
  24 #if defined(_MSC_VER)
  25 #  define MOZ_ALWAYS_INLINE_EVEN_DEBUG     __forceinline
  26 #elif defined(__GNUC__)
  27 #  define MOZ_ALWAYS_INLINE_EVEN_DEBUG     __attribute__((always_inline)) inline
  28 #else
  29 #  define MOZ_ALWAYS_INLINE_EVEN_DEBUG     inline
  30 #endif
  31
  32 #if !defined(DEBUG)
  33 #  define MOZ_ALWAYS_INLINE     MOZ_ALWAYS_INLINE_EVEN_DEBUG
  34 #elif defined(_MSC_VER) && !defined(__cplusplus)
  35 #  define MOZ_ALWAYS_INLINE     __inline
  36 #else
  37 #  define MOZ_ALWAYS_INLINE     inline
  38 #endif
  39
  40 #if defined(_MSC_VER)
  41 /*
  42  * g++ requires -std=c++0x or -std=gnu++0x to support C++11 functionality
  43  * without warnings (functionality used by the macros below).  These modes are
  44  * detectable by checking whether __GXX_EXPERIMENTAL_CXX0X__ is defined or, more
  45  * standardly, by checking whether __cplusplus has a C++11 or greater value.
  46  * Current versions of g++ do not correctly set __cplusplus, so we check both
  47  * for forward compatibility.
  48  *
  49  * Even though some versions of MSVC support explicit conversion operators, we
  50  * don't indicate support for them here, due to
  51  * http://stackoverflow.com/questions/20498142/visual-studio-2013-explicit-keyword-bug
  52  */
  53 #  define MOZ_HAVE_CXX11_FINAL         final
  54 #  define MOZ_HAVE_CXX11_OVERRIDE
  55 #  define MOZ_HAVE_NEVER_INLINE          __declspec(noinline)
  56 #  define MOZ_HAVE_NORETURN              __declspec(noreturn)
  57 #  ifdef __clang__
  58      /* clang-cl probably supports constexpr and explicit conversions. */
  59 #    if __has_extension(cxx_constexpr)
  60 #      define MOZ_HAVE_CXX11_CONSTEXPR
  61 #    endif
  62 #    if __has_extension(cxx_explicit_conversions)
  63 #      define MOZ_HAVE_EXPLICIT_CONVERSION
  64 #    endif
  65 #  endif
  66 #elif defined(__clang__)
  67    /*
  68     * Per Clang documentation, "Note that marketing version numbers should not
  69     * be used to check for language features, as different vendors use different
  70     * numbering schemes. Instead, use the feature checking macros."
  71     */
  72 #  ifndef __has_extension
  73 #    define __has_extension __has_feature /* compatibility, for older versions of clang */
  74 #  endif
  75 #  if __has_extension(cxx_constexpr)
  76 #    define MOZ_HAVE_CXX11_CONSTEXPR
  77 #  endif
  78 #  if __has_extension(cxx_explicit_conversions)
  79 #    define MOZ_HAVE_EXPLICIT_CONVERSION
  80 #  endif
  81 #  if __has_extension(cxx_override_control)
  82 #    define MOZ_HAVE_CXX11_OVERRIDE
  83 #    define MOZ_HAVE_CXX11_FINAL         final
  84 #  endif
  85 #  if __has_attribute(noinline)
  86 #    define MOZ_HAVE_NEVER_INLINE        __attribute__((noinline))
  87 #  endif
  88 #  if __has_attribute(noreturn)
  89 #    define MOZ_HAVE_NORETURN            __attribute__((noreturn))
  90 #  endif
  91 #elif defined(__GNUC__)
  92 #  if defined(__GXX_EXPERIMENTAL_CXX0X__) || __cplusplus >= 201103L
  93 #    if MOZ_GCC_VERSION_AT_LEAST(4, 7, 0)
  94 #      define MOZ_HAVE_CXX11_OVERRIDE
  95 #      define MOZ_HAVE_CXX11_FINAL       final
  96 #    endif
  97 #    if MOZ_GCC_VERSION_AT_LEAST(4, 6, 0)
  98 #      define MOZ_HAVE_CXX11_CONSTEXPR
  99 #    endif
 100 #    if MOZ_GCC_VERSION_AT_LEAST(4, 5, 0)
 101 #      define MOZ_HAVE_EXPLICIT_CONVERSION
 102 #    endif
 103 #  else
 104      /* __final is a non-C++11 GCC synonym for 'final', per GCC r176655. */
 105 #    if MOZ_GCC_VERSION_AT_LEAST(4, 7, 0)
 106 #      define MOZ_HAVE_CXX11_FINAL       __final
 107 #    endif
 108 #  endif
 109 #  define MOZ_HAVE_NEVER_INLINE          __attribute__((noinline))
 110 #  define MOZ_HAVE_NORETURN              __attribute__((noreturn))
 111 #endif
 112
 113 /*
 114  * When built with clang analyzer (a.k.a scan-build), define MOZ_HAVE_NORETURN
 115  * to mark some false positives
 116  */
 117 #ifdef __clang_analyzer__
 118 #  if __has_extension(attribute_analyzer_noreturn)
 119 #    define MOZ_HAVE_ANALYZER_NORETURN __attribute__((analyzer_noreturn))
 120 #  endif
 121 #endif
 122
 123 /*
 124  * The MOZ_CONSTEXPR specifier declares that a C++11 compiler can evaluate a
 125  * function at compile time. A constexpr function cannot examine any values
 126  * except its arguments and can have no side effects except its return value.
 127  * The MOZ_CONSTEXPR_VAR specifier tells a C++11 compiler that a variable's
 128  * value may be computed at compile time.  It should be prefered to just
 129  * marking variables as MOZ_CONSTEXPR because if the compiler does not support
 130  * constexpr it will fall back to making the variable const, and some compilers
 131  * do not accept variables being marked both const and constexpr.
 132  */
 133 #ifdef MOZ_HAVE_CXX11_CONSTEXPR
 134 #  define MOZ_CONSTEXPR         constexpr
 135 #  define MOZ_CONSTEXPR_VAR     constexpr
 136 #else
 137 #  define MOZ_CONSTEXPR         /* no support */
 138 #  define MOZ_CONSTEXPR_VAR     const
 139 #endif
 140
 141 /*
 142  * MOZ_EXPLICIT_CONVERSION is a specifier on a type conversion
 143  * overloaded operator that declares that a C++11 compiler should restrict
 144  * this operator to allow only explicit type conversions, disallowing
 145  * implicit conversions.
 146  *
 147  * Example:
 148  *
 149  *   template<typename T>
 150  *   class Ptr
 151  *   {
 152  *     T* mPtr;
 153  *     MOZ_EXPLICIT_CONVERSION operator bool() const
 154  *     {
 155  *       return mPtr != nullptr;
 156  *     }
 157  *   };
 158  *
 159  */
 160 #ifdef MOZ_HAVE_EXPLICIT_CONVERSION
 161 #  define MOZ_EXPLICIT_CONVERSION explicit
 162 #else
 163 #  define MOZ_EXPLICIT_CONVERSION /* no support */
 164 #endif
 165
 166 /*
 167  * MOZ_NEVER_INLINE is a macro which expands to tell the compiler that the
 168  * method decorated with it must never be inlined, even if the compiler would
 169  * otherwise choose to inline the method.  Compilers aren't absolutely
 170  * guaranteed to support this, but most do.
 171  */
 172 #if defined(MOZ_HAVE_NEVER_INLINE)
 173 #  define MOZ_NEVER_INLINE      MOZ_HAVE_NEVER_INLINE
 174 #else
 175 #  define MOZ_NEVER_INLINE      /* no support */
 176 #endif
 177
 178 /*
 179  * MOZ_NORETURN, specified at the start of a function declaration, indicates
 180  * that the given function does not return.  (The function definition does not
 181  * need to be annotated.)
 182  *
 183  *   MOZ_NORETURN void abort(const char* msg);
 184  *
 185  * This modifier permits the compiler to optimize code assuming a call to such a
 186  * function will never return.  It also enables the compiler to avoid spurious
 187  * warnings about not initializing variables, or about any other seemingly-dodgy
 188  * operations performed after the function returns.
 189  *
 190  * This modifier does not affect the corresponding function's linking behavior.
 191  */
 192 #if defined(MOZ_HAVE_NORETURN)
 193 #  define MOZ_NORETURN          MOZ_HAVE_NORETURN
 194 #else
 195 #  define MOZ_NORETURN          /* no support */
 196 #endif
 197
 198 /*
 199  * MOZ_PRETEND_NORETURN_FOR_STATIC_ANALYSIS, specified at the end of a function
 200  * declaration, indicates that for the purposes of static analysis, this
 201  * function does not return.  (The function definition does not need to be
 202  * annotated.)
 203  *
 204  * MOZ_ReportCrash(const char* s, const char* file, int ln)
 205  *   MOZ_PRETEND_NORETURN_FOR_STATIC_ANALYSIS
 206  *
 207  * Some static analyzers, like scan-build from clang, can use this information
 208  * to eliminate false positives.  From the upstream documentation of scan-build:
 209  * "This attribute is useful for annotating assertion handlers that actually
 210  * can return, but for the purpose of using the analyzer we want to pretend
 211  * that such functions do not return."
 212  *
 213  */
 214 #if defined(MOZ_HAVE_ANALYZER_NORETURN)
 215 #  define MOZ_PRETEND_NORETURN_FOR_STATIC_ANALYSIS          MOZ_HAVE_ANALYZER_NORETURN
 216 #else
 217 #  define MOZ_PRETEND_NORETURN_FOR_STATIC_ANALYSIS          /* no support */
 218 #endif
 219
 220 /*
 221  * MOZ_ASAN_BLACKLIST is a macro to tell AddressSanitizer (a compile-time
 222  * instrumentation shipped with Clang and GCC) to not instrument the annotated
 223  * function. Furthermore, it will prevent the compiler from inlining the
 224  * function because inlining currently breaks the blacklisting mechanism of
 225  * AddressSanitizer.
 226  */
 227 #if defined(__has_feature)
 228 #  if __has_feature(address_sanitizer)
 229 #    define MOZ_HAVE_ASAN_BLACKLIST
 230 #  endif
 231 #elif defined(__GNUC__)
 232 #  if defined(__SANITIZE_ADDRESS__)
 233 #    define MOZ_HAVE_ASAN_BLACKLIST
 234 #  endif
 235 #endif
 236
 237 #if defined(MOZ_HAVE_ASAN_BLACKLIST)
 238 #  define MOZ_ASAN_BLACKLIST MOZ_NEVER_INLINE __attribute__((no_sanitize_address))
 239 #else
 240 #  define MOZ_ASAN_BLACKLIST /* nothing */
 241 #endif
 242
 243 /*
 244  * MOZ_TSAN_BLACKLIST is a macro to tell ThreadSanitizer (a compile-time
 245  * instrumentation shipped with Clang) to not instrument the annotated function.
 246  * Furthermore, it will prevent the compiler from inlining the function because
 247  * inlining currently breaks the blacklisting mechanism of ThreadSanitizer.
 248  */
 249 #if defined(__has_feature)
 250 #  if __has_feature(thread_sanitizer)
 251 #    define MOZ_TSAN_BLACKLIST MOZ_NEVER_INLINE __attribute__((no_sanitize_thread))
 252 #  else
 253 #    define MOZ_TSAN_BLACKLIST /* nothing */
 254 #  endif
 255 #else
 256 #  define MOZ_TSAN_BLACKLIST /* nothing */
 257 #endif
 258
 259 #ifdef __cplusplus
 260
 261 /*
 262  * MOZ_OVERRIDE explicitly indicates that a virtual member function in a class
 263  * overrides a member function of a base class, rather than potentially being a
 264  * new member function.  MOZ_OVERRIDE should be placed immediately before the
 265  * ';' terminating the member function's declaration, or before '= 0;' if the
 266  * member function is pure.  If the member function is defined in the class
 267  * definition, it should appear before the opening brace of the function body.
 268  *
 269  *   class Base
 270  *   {
 271  *   public:
 272  *     virtual void f() = 0;
 273  *   };
 274  *   class Derived1 : public Base
 275  *   {
 276  *   public:
 277  *     virtual void f() MOZ_OVERRIDE;
 278  *   };
 279  *   class Derived2 : public Base
 280  *   {
 281  *   public:
 282  *     virtual void f() MOZ_OVERRIDE = 0;
 283  *   };
 284  *   class Derived3 : public Base
 285  *   {
 286  *   public:
 287  *     virtual void f() MOZ_OVERRIDE { }
 288  *   };
 289  *
 290  * In compilers supporting C++11 override controls, MOZ_OVERRIDE *requires* that
 291  * the function marked with it override a member function of a base class: it
 292  * is a compile error if it does not.  Otherwise MOZ_OVERRIDE does not affect
 293  * semantics and merely documents the override relationship to the reader (but
 294  * of course must still be used correctly to not break C++11 compilers).
 295  */
 296 #if defined(MOZ_HAVE_CXX11_OVERRIDE)
 297 #  define MOZ_OVERRIDE          override
 298 #else
 299 #  define MOZ_OVERRIDE          /* no support */
 300 #endif
 301
 302 /*
 303  * MOZ_FINAL indicates that some functionality cannot be overridden through
 304  * inheritance.  It can be used to annotate either classes/structs or virtual
 305  * member functions.
 306  *
 307  * To annotate a class/struct with MOZ_FINAL, place MOZ_FINAL immediately after
 308  * the name of the class, before the list of classes from which it derives (if
 309  * any) and before its opening brace.  MOZ_FINAL must not be used to annotate
 310  * unnamed classes or structs.  (With some compilers, and with C++11 proper, the
 311  * underlying expansion is ambiguous with specifying a class name.)
 312  *
 313  *   class Base MOZ_FINAL
 314  *   {
 315  *   public:
 316  *     Base();
 317  *     ~Base();
 318  *     virtual void f() { }
 319  *   };
 320  *   // This will be an error in some compilers:
 321  *   class Derived : public Base
 322  *   {
 323  *   public:
 324  *     ~Derived() { }
 325  *   };
 326  *
 327  * One particularly common reason to specify MOZ_FINAL upon a class is to tell
 328  * the compiler that it's not dangerous for it to have a non-virtual destructor
 329  * yet have one or more virtual functions, silencing the warning it might emit
 330  * in this case.  Suppose Base above weren't annotated with MOZ_FINAL.  Because
 331  * ~Base() is non-virtual, an attempt to delete a Derived* through a Base*
 332  * wouldn't call ~Derived(), so any cleanup ~Derived() might do wouldn't happen.
 333  * (Formally C++ says behavior is undefined, but compilers will likely just call
 334  * ~Base() and not ~Derived().)  Specifying MOZ_FINAL tells the compiler that
 335  * it's safe for the destructor to be non-virtual.
 336  *
 337  * In compilers implementing final controls, it is an error to inherit from a
 338  * class annotated with MOZ_FINAL.  In other compilers it serves only as
 339  * documentation.
 340  *
 341  * To annotate a virtual member function with MOZ_FINAL, place MOZ_FINAL
 342  * immediately before the ';' terminating the member function's declaration, or
 343  * before '= 0;' if the member function is pure.  If the member function is
 344  * defined in the class definition, it should appear before the opening brace of
 345  * the function body.  (This placement is identical to that for MOZ_OVERRIDE.
 346  * If both are used, they should appear in the order 'MOZ_FINAL MOZ_OVERRIDE'
 347  * for consistency.)
 348  *
 349  *   class Base
 350  *   {
 351  *   public:
 352  *     virtual void f() MOZ_FINAL;
 353  *   };
 354  *   class Derived
 355  *   {
 356  *   public:
 357  *     // This will be an error in some compilers:
 358  *     virtual void f();
 359  *   };
 360  *
 361  * In compilers implementing final controls, it is an error for a derived class
 362  * to override a method annotated with MOZ_FINAL.  In other compilers it serves
 363  * only as documentation.
 364  */
 365 #if defined(MOZ_HAVE_CXX11_FINAL)
 366 #  define MOZ_FINAL             MOZ_HAVE_CXX11_FINAL
 367 #else
 368 #  define MOZ_FINAL             /* no support */
 369 #endif
 370
 371 /**
 372  * MOZ_WARN_UNUSED_RESULT tells the compiler to emit a warning if a function's
 373  * return value is not used by the caller.
 374  *
 375  * Place this attribute at the very beginning of a function definition. For
 376  * example, write
 377  *
 378  *   MOZ_WARN_UNUSED_RESULT int foo();
 379  *
 380  * or
 381  *
 382  *   MOZ_WARN_UNUSED_RESULT int foo() { return 42; }
 383  */
 384 #if defined(__GNUC__) || defined(__clang__)
 385 #  define MOZ_WARN_UNUSED_RESULT __attribute__ ((warn_unused_result))
 386 #else
 387 #  define MOZ_WARN_UNUSED_RESULT
 388 #endif
 389
 390 /*
 391  * The following macros are attributes that support the static analysis plugin
 392  * included with Mozilla, and will be implemented (when such support is enabled)
 393  * as C++11 attributes. Since such attributes are legal pretty much everywhere
 394  * and have subtly different semantics depending on their placement, the
 395  * following is a guide on where to place the attributes.
 396  *
 397  * Attributes that apply to a struct or class precede the name of the class:
 398  * (Note that this is different from the placement of MOZ_FINAL for classes!)
 399  *
 400  *   class MOZ_CLASS_ATTRIBUTE SomeClass {};
 401  *
 402  * Attributes that apply to functions follow the parentheses and const
 403  * qualifiers but precede MOZ_FINAL, MOZ_OVERRIDE and the function body:
 404  *
 405  *   void DeclaredFunction() MOZ_FUNCTION_ATTRIBUTE;
 406  *   void SomeFunction() MOZ_FUNCTION_ATTRIBUTE {}
 407  *   void PureFunction() const MOZ_FUNCTION_ATTRIBUTE = 0;
 408  *   void OverriddenFunction() MOZ_FUNCTION_ATTIRBUTE MOZ_OVERRIDE;
 409  *
 410  * Attributes that apply to variables or parameters follow the variable's name:
 411  *
 412  *   int variable MOZ_VARIABLE_ATTRIBUTE;
 413  *
 414  * Attributes that apply to types follow the type name:
 415  *
 416  *   typedef int MOZ_TYPE_ATTRIBUTE MagicInt;
 417  *   int MOZ_TYPE_ATTRIBUTE someVariable;
 418  *   int* MOZ_TYPE_ATTRIBUTE magicPtrInt;
 419  *   int MOZ_TYPE_ATTRIBUTE* ptrToMagicInt;
 420  *
 421  * Attributes that apply to statements precede the statement:
 422  *
 423  *   MOZ_IF_ATTRIBUTE if (x == 0)
 424  *   MOZ_DO_ATTRIBUTE do { } while (0);
 425  *
 426  * Attributes that apply to labels precede the label:
 427  *
 428  *   MOZ_LABEL_ATTRIBUTE target:
 429  *     goto target;
 430  *   MOZ_CASE_ATTRIBUTE case 5:
 431  *   MOZ_DEFAULT_ATTRIBUTE default:
 432  *
 433  * The static analyses that are performed by the plugin are as follows:
 434  *
 435  * MOZ_MUST_OVERRIDE: Applies to all C++ member functions. All immediate
 436  *   subclasses must provide an exact override of this method; if a subclass
 437  *   does not override this method, the compiler will emit an error. This
 438  *   attribute is not limited to virtual methods, so if it is applied to a
 439  *   nonvirtual method and the subclass does not provide an equivalent
 440  *   definition, the compiler will emit an error.
 441  * MOZ_STACK_CLASS: Applies to all classes. Any class with this annotation is
 442  *   expected to live on the stack, so it is a compile-time error to use it, or
 443  *   an array of such objects, as a global or static variable, or as the type of
 444  *   a new expression (unless placement new is being used). If a member of
 445  *   another class uses this class, or if another class inherits from this
 446  *   class, then it is considered to be a stack class as well, although this
 447  *   attribute need not be provided in such cases.
 448  * MOZ_NONHEAP_CLASS: Applies to all classes. Any class with this annotation is
 449  *   expected to live on the stack or in static storage, so it is a compile-time
 450  *   error to use it, or an array of such objects, as the type of a new
 451  *   expression (unless placement new is being used). If a member of another
 452  *   class uses this class, or if another class inherits from this class, then
 453  *   it is considered to be a non-heap class as well, although this attribute
 454  *   need not be provided in such cases.
 455  * MOZ_ONLY_USED_TO_AVOID_STATIC_CONSTRUCTORS: Applies to all classes that are
 456  *   intended to prevent introducing static initializers.  This attribute
 457  *   currently makes it a compile-time error to instantiate these classes
 458  *   anywhere other than at the global scope, or as a static member of a class.
 459  * MOZ_TRIVIAL_CTOR_DTOR: Applies to all classes that must have both a trivial
 460  *   constructor and a trivial destructor.  Setting this attribute on a class
 461  *   makes it a compile-time error for that class to get a non-trivial
 462  *   constructor or destructor for any reason.
 463  * MOZ_HEAP_ALLOCATOR: Applies to any function. This indicates that the return
 464  *   value is allocated on the heap, and will as a result check such allocations
 465  *   during MOZ_STACK_CLASS and MOZ_NONHEAP_CLASS annotation checking.
 466  * MOZ_IMPLICIT: Applies to constructors. Implicit conversion constructors
 467  *   are disallowed by default unless they are marked as MOZ_IMPLICIT. This
 468  *   attribute must be used for constructors which intend to provide implicit
 469  *   conversions.
 470  * MOZ_NO_ARITHMETIC_EXPR_IN_ARGUMENT: Applies to functions. Makes it a compile
 471  *   time error to pass arithmetic expressions on variables to the function.
 472  * MOZ_OWNING_REF: Applies to declarations of pointer types.  This attribute
 473  *   tells the compiler that the raw pointer is a strong reference, and that
 474  *   property is somehow enforced by the code.  This can make the compiler
 475  *   ignore these pointers when validating the usage of pointers otherwise.
 476  * MOZ_NON_OWNING_REF: Applies to declarations of pointer types.  This attribute
 477  *   tells the compiler that the raw pointer is a weak reference, and that
 478  *   property is somehow enforced by the code.  This can make the compiler
 479  *   ignore these pointers when validating the usage of pointers otherwise.
 480  * MOZ_UNSAFE_REF: Applies to declarations of pointer types.  This attribute
 481  *   should be used for non-owning references that can be unsafe, and their
 482  *   safety needs to be validated through code inspection.  The string argument
 483  *   passed to this macro documents the safety conditions.
 484  * MOZ_NO_ADDREF_RELEASE_ON_RETURN: Applies to function declarations.  Makes it
 485  *   a compile time error to call AddRef or Release on the return value of a
 486  *   function.  This is intended to be used with operator->() of our smart
 487  *   pointer classes to ensure that the refcount of an object wrapped in a
 488  *   smart pointer is not manipulated directly.
 489  */
 490 #ifdef MOZ_CLANG_PLUGIN
 491 #  define MOZ_MUST_OVERRIDE __attribute__((annotate("moz_must_override")))
 492 #  define MOZ_STACK_CLASS __attribute__((annotate("moz_stack_class")))
 493 #  define MOZ_NONHEAP_CLASS __attribute__((annotate("moz_nonheap_class")))
 494 #  define MOZ_TRIVIAL_CTOR_DTOR __attribute__((annotate("moz_trivial_ctor_dtor")))
 495 #  ifdef DEBUG
 496      /* in debug builds, these classes do have non-trivial constructors. */
 497 #    define MOZ_ONLY_USED_TO_AVOID_STATIC_CONSTRUCTORS __attribute__((annotate("moz_global_class")))
 498 #  else
 499 #    define MOZ_ONLY_USED_TO_AVOID_STATIC_CONSTRUCTORS __attribute__((annotate("moz_global_class"))) \
 500             MOZ_TRIVIAL_CTOR_DTOR
 501 #  endif
 502 #  define MOZ_IMPLICIT __attribute__((annotate("moz_implicit")))
 503 #  define MOZ_NO_ARITHMETIC_EXPR_IN_ARGUMENT __attribute__((annotate("moz_no_arith_expr_in_arg")))
 504 #  define MOZ_OWNING_REF __attribute__((annotate("moz_strong_ref")))
 505 #  define MOZ_NON_OWNING_REF __attribute__((annotate("moz_weak_ref")))
 506 #  define MOZ_UNSAFE_REF(reason) __attribute__((annotate("moz_strong_ref")))
 507 #  define MOZ_NO_ADDREF_RELEASE_ON_RETURN __attribute__((annotate("moz_no_addref_release_on_return")))
 508 /*
 509  * It turns out that clang doesn't like void func() __attribute__ {} without a
 510  * warning, so use pragmas to disable the warning. This code won't work on GCC
 511  * anyways, so the warning is safe to ignore.
 512  */
 513 #  define MOZ_HEAP_ALLOCATOR \
 514     _Pragma("clang diagnostic push") \
 515     _Pragma("clang diagnostic ignored \"-Wgcc-compat\"") \
 516     __attribute__((annotate("moz_heap_allocator"))) \
 517     _Pragma("clang diagnostic pop")
 518 #else
 519 #  define MOZ_MUST_OVERRIDE /* nothing */
 520 #  define MOZ_STACK_CLASS /* nothing */
 521 #  define MOZ_NONHEAP_CLASS /* nothing */
 522 #  define MOZ_TRIVIAL_CTOR_DTOR /* nothing */
 523 #  define MOZ_ONLY_USED_TO_AVOID_STATIC_CONSTRUCTORS /* nothing */
 524 #  define MOZ_IMPLICIT /* nothing */
 525 #  define MOZ_NO_ARITHMETIC_EXPR_IN_ARGUMENT /* nothing */
 526 #  define MOZ_HEAP_ALLOCATOR /* nothing */
 527 #  define MOZ_OWNING_REF /* nothing */
 528 #  define MOZ_NON_OWNING_REF /* nothing */
 529 #  define MOZ_UNSAFE_REF(reason) /* nothing */
 530 #  define MOZ_NO_ADDREF_RELEASE_ON_RETURN /* nothing */
 531 #endif /* MOZ_CLANG_PLUGIN */
 532
 533 #endif /* __cplusplus */
 534
 535 #endif /* mozilla_Attributes_h */