/* -*- Mode: C++; tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 4 -*- * vim: set ts=8 sw=4 et tw=99 ft=cpp: * * ***** BEGIN LICENSE BLOCK ***** * Version: MPL 1.1/GPL 2.0/LGPL 2.1 * * The contents of this file are subject to the Mozilla Public License Version * 1.1 (the "License"); you may not use this file except in compliance with * the License. You may obtain a copy of the License at: * http://www.mozilla.org/MPL/ * * Software distributed under the License is distributed on an "AS IS" basis, * WITHOUT WARRANTY OF ANY KIND, either express or implied. See the License * for the specific language governing rights and limitations under the * License. * * The Original Code is Mozilla Code. * * The Initial Developer of the Original Code is * The Mozilla Foundation * Portions created by the Initial Developer are Copyright (C) 2011 * the Initial Developer. All Rights Reserved. * * Contributor(s): * Jeff Walden * * Alternatively, the contents of this file may be used under the terms of * either the GNU General Public License Version 2 or later (the "GPL"), or * the GNU Lesser General Public License Version 2.1 or later (the "LGPL"), * in which case the provisions of the GPL or the LGPL are applicable instead * of those above. If you wish to allow use of your version of this file only * under the terms of either the GPL or the LGPL, and not to allow others to * use your version of this file under the terms of the MPL, indicate your * decision by deleting the provisions above and replace them with the notice * and other provisions required by the GPL or the LGPL. If you do not delete * the provisions above, a recipient may use your version of this file under * the terms of any one of the MPL, the GPL or the LGPL. * * ***** END LICENSE BLOCK ***** */ /* Implementations of runtime and static assertion macros for C and C++. */ #ifndef mozilla_Assertions_h_ #define mozilla_Assertions_h_ #include "mozilla/Attributes.h" #include "mozilla/Types.h" /* * MOZ_STATIC_ASSERT may be used to assert a condition *at compile time*. This * can be useful when you make certain assumptions about what must hold for * optimal, or even correct, behavior. For example, you might assert that the * size of a struct is a multiple of the target architecture's word size: * * struct S { ... }; * MOZ_STATIC_ASSERT(sizeof(S) % sizeof(size_t) == 0, * "S should be a multiple of word size for efficiency"); * * This macro can be used in any location where both an extern declaration and a * typedef could be used. * * Be aware of the gcc 4.2 concerns noted further down when writing patches that * use this macro, particularly if a patch only bounces on OS X. */ #ifdef __cplusplus # if defined(__clang__) # ifndef __has_extension # define __has_extension __has_feature /* compatibility, for older versions of clang */ # endif # if __has_extension(cxx_static_assert) # define MOZ_STATIC_ASSERT(cond, reason) static_assert((cond), reason) # endif # elif defined(__GNUC__) # if (defined(__GXX_EXPERIMENTAL_CXX0X__) || __cplusplus >= 201103L) && \ (__GNUC__ > 4 || (__GNUC__ == 4 && __GNUC_MINOR__ >= 3)) # define MOZ_STATIC_ASSERT(cond, reason) static_assert((cond), reason) # endif # elif defined(_MSC_VER) # if _MSC_VER >= 1600 /* MSVC 10 */ # define MOZ_STATIC_ASSERT(cond, reason) static_assert((cond), reason) # endif # elif defined(__HP_aCC) # if __HP_aCC >= 62500 && defined(_HP_CXX0x_SOURCE) # define MOZ_STATIC_ASSERT(cond, reason) static_assert((cond), reason) # endif # endif #endif #ifndef MOZ_STATIC_ASSERT # define MOZ_STATIC_ASSERT_GLUE1(x, y) x##y # define MOZ_STATIC_ASSERT_GLUE(x, y) MOZ_STATIC_ASSERT_GLUE1(x, y) # if defined(__SUNPRO_CC) /* * The Sun Studio C++ compiler is buggy when declaring, inside a function, * another extern'd function with an array argument whose length contains a * sizeof, triggering the error message "sizeof expression not accepted as * size of array parameter". This bug (6688515, not public yet) would hit * defining moz_static_assert as a function, so we always define an extern * array for Sun Studio. * * We include the line number in the symbol name in a best-effort attempt * to avoid conflicts (see below). */ # define MOZ_STATIC_ASSERT(cond, reason) \ extern char MOZ_STATIC_ASSERT_GLUE(moz_static_assert, __LINE__)[(cond) ? 1 : -1] # elif defined(__COUNTER__) /* * If there was no preferred alternative, use a compiler-agnostic version. * * Note that the non-__COUNTER__ version has a bug in C++: it can't be used * in both |extern "C"| and normal C++ in the same translation unit. (Alas * |extern "C"| isn't allowed in a function.) The only affected compiler * we really care about is gcc 4.2. For that compiler and others like it, * we include the line number in the function name to do the best we can to * avoid conflicts. These should be rare: a conflict would require use of * MOZ_STATIC_ASSERT on the same line in separate files in the same * translation unit, *and* the uses would have to be in code with * different linkage, *and* the first observed use must be in C++-linkage * code. */ # define MOZ_STATIC_ASSERT(cond, reason) \ typedef int MOZ_STATIC_ASSERT_GLUE(moz_static_assert, __COUNTER__)[(cond) ? 1 : -1] # else # define MOZ_STATIC_ASSERT(cond, reason) \ extern void MOZ_STATIC_ASSERT_GLUE(moz_static_assert, __LINE__)(int arg[(cond) ? 1 : -1]) # endif #endif #define MOZ_STATIC_ASSERT_IF(cond, expr, reason) MOZ_STATIC_ASSERT(!(cond) || (expr), reason) #ifdef __cplusplus extern "C" { #endif extern MFBT_API(void) MOZ_Crash(void); extern MFBT_API(void) MOZ_Assert(const char* s, const char* file, int ln); #ifdef __cplusplus } /* extern "C" */ #endif /* * MOZ_ASSERT(expr [, explanation-string]) asserts that |expr| must be truthy in * debug builds. If it is, execution continues. Otherwise, an error message * including the expression and the explanation-string (if provided) is printed, * an attempt is made to invoke any existing debugger, and execution halts. * MOZ_ASSERT is fatal: no recovery is possible. Do not assert a condition * which can correctly be falsy. * * The optional explanation-string, if provided, must be a string literal * explaining the assertion. It is intended for use with assertions whose * correctness or rationale is non-obvious, and for assertions where the "real" * condition being tested is best described prosaically. Don't provide an * explanation if it's not actually helpful. * * // No explanation needed: pointer arguments often must not be NULL. * MOZ_ASSERT(arg); * * // An explanation can be helpful to explain exactly how we know an * // assertion is valid. * MOZ_ASSERT(state == WAITING_FOR_RESPONSE, * "given that and , we must have..."); * * // Or it might disambiguate multiple identical (save for their location) * // assertions of the same expression. * MOZ_ASSERT(getSlot(PRIMITIVE_THIS_SLOT).isUndefined(), * "we already set [[PrimitiveThis]] for this Boolean object"); * MOZ_ASSERT(getSlot(PRIMITIVE_THIS_SLOT).isUndefined(), * "we already set [[PrimitiveThis]] for this String object"); * * MOZ_ASSERT has no effect in non-debug builds. It is designed to catch bugs * *only* during debugging, not "in the field". */ #ifdef DEBUG /* First the single-argument form. */ # define MOZ_ASSERT_HELPER1(expr) \ ((expr) ? ((void)0) : MOZ_Assert(#expr, __FILE__, __LINE__)) /* Now the two-argument form. */ # define MOZ_ASSERT_HELPER2(expr, explain) \ ((expr) ? ((void)0) : MOZ_Assert(#expr " (" explain ")", __FILE__, __LINE__)) /* And now, helper macrology up the wazoo. */ /* * Count the number of arguments passed to MOZ_ASSERT, very carefully * tiptoeing around an MSVC bug where it improperly expands __VA_ARGS__ as a * single token in argument lists. See these URLs for details: * * http://connect.microsoft.com/VisualStudio/feedback/details/380090/variadic-macro-replacement * http://cplusplus.co.il/2010/07/17/variadic-macro-to-count-number-of-arguments/#comment-644 */ # define MOZ_COUNT_ASSERT_ARGS_IMPL2(_1, _2, count, ...) \ count # define MOZ_COUNT_ASSERT_ARGS_IMPL(args) \ MOZ_COUNT_ASSERT_ARGS_IMPL2 args # define MOZ_COUNT_ASSERT_ARGS(...) \ MOZ_COUNT_ASSERT_ARGS_IMPL((__VA_ARGS__, 2, 1, 0)) /* Pick the right helper macro to invoke. */ # define MOZ_ASSERT_CHOOSE_HELPER2(count) MOZ_ASSERT_HELPER##count # define MOZ_ASSERT_CHOOSE_HELPER1(count) MOZ_ASSERT_CHOOSE_HELPER2(count) # define MOZ_ASSERT_CHOOSE_HELPER(count) MOZ_ASSERT_CHOOSE_HELPER1(count) /* The actual macro. */ # define MOZ_ASSERT_GLUE(x, y) x y # define MOZ_ASSERT(...) \ MOZ_ASSERT_GLUE(MOZ_ASSERT_CHOOSE_HELPER(MOZ_COUNT_ASSERT_ARGS(__VA_ARGS__)), \ (__VA_ARGS__)) #else # define MOZ_ASSERT(...) ((void)0) #endif /* DEBUG */ /* * MOZ_ASSERT_IF(cond1, cond2) is equivalent to MOZ_ASSERT(cond2) if cond1 is * true. * * MOZ_ASSERT_IF(isPrime(num), num == 2 || isOdd(num)); * * As with MOZ_ASSERT, MOZ_ASSERT_IF has effect only in debug builds. It is * designed to catch bugs during debugging, not "in the field". */ #ifdef DEBUG # define MOZ_ASSERT_IF(cond, expr) ((cond) ? MOZ_ASSERT(expr) : ((void)0)) #else # define MOZ_ASSERT_IF(cond, expr) ((void)0) #endif /* MOZ_NOT_REACHED_MARKER() expands (in compilers which support it) to an * expression which states that it is undefined behavior for the compiler to * reach this point. Most code should probably use the higher level * MOZ_NOT_REACHED (which expands to this when appropriate). */ #if defined(__clang__) # define MOZ_NOT_REACHED_MARKER() __builtin_unreachable() #elif defined(__GNUC__) # if __GNUC__ > 4 || (__GNUC__ == 4 && __GNUC_MINOR__ >= 5) # define MOZ_NOT_REACHED_MARKER() __builtin_unreachable() # endif #elif defined(_MSC_VER) # define MOZ_NOT_REACHED_MARKER() __assume(0) #endif /* * MOZ_NOT_REACHED(reason) indicates that the given point can't be reached * during execution: simply reaching that point in execution is a bug. It takes * as an argument an error message indicating the reason why that point should * not have been reachable. * * // ...in a language parser... * void handle(BooleanLiteralNode node) * { * if (node.isTrue()) * handleTrueLiteral(); * else if (node.isFalse()) * handleFalseLiteral(); * else * MOZ_NOT_REACHED("boolean literal that's not true or false?"); * } */ #if defined(MOZ_NOT_REACHED_MARKER) # if defined(DEBUG) # define MOZ_NOT_REACHED(reason) do { \ MOZ_Assert(reason, __FILE__, __LINE__); \ MOZ_NOT_REACHED_MARKER(); \ } while (0) # else # define MOZ_NOT_REACHED(reason) MOZ_NOT_REACHED_MARKER() # endif #else # if defined(__GNUC__) /* * On older versions of gcc we need to call a noreturn function to mark the * code as unreachable. Since what we want is an unreachable version of * MOZ_Assert, we use an asm label * (http://gcc.gnu.org/onlinedocs/gcc-4.6.2/gcc/Asm-Labels.html) to create * a new declaration to the same symbol. MOZ_ASSERT_NR should only be * used via this macro, as it is a very specific hack to older versions of * gcc. */ # define MOZ_GETASMPREFIX2(X) #X # define MOZ_GETASMPREFIX(X) MOZ_GETASMPREFIX2(X) # define MOZ_ASMPREFIX MOZ_GETASMPREFIX(__USER_LABEL_PREFIX__) extern MOZ_NORETURN MFBT_API(void) MOZ_ASSERT_NR(const char* s, const char* file, int ln) \ asm (MOZ_ASMPREFIX "MOZ_Assert"); # define MOZ_NOT_REACHED(reason) MOZ_ASSERT_NR(reason, __FILE__, __LINE__) # elif defined(DEBUG) # define MOZ_NOT_REACHED(reason) MOZ_Assert(reason, __FILE__, __LINE__) # else # define MOZ_NOT_REACHED(reason) ((void)0) # endif #endif /* * MOZ_ALWAYS_TRUE(expr) and MOZ_ALWAYS_FALSE(expr) always evaluate the provided * expression, in debug builds and in release builds both. Then, in debug * builds only, the value of the expression is asserted either true or false * using MOZ_ASSERT. */ #ifdef DEBUG # define MOZ_ALWAYS_TRUE(expr) MOZ_ASSERT((expr)) # define MOZ_ALWAYS_FALSE(expr) MOZ_ASSERT(!(expr)) #else # define MOZ_ALWAYS_TRUE(expr) ((void)(expr)) # define MOZ_ALWAYS_FALSE(expr) ((void)(expr)) #endif #endif /* mozilla_Assertions_h_ */