diff --git a/base/include/android-base/macros.h b/base/include/android-base/macros.h index 174866570..5abf5141f 100644 --- a/base/include/android-base/macros.h +++ b/base/include/android-base/macros.h @@ -75,46 +75,6 @@ char(&ArraySizeHelper(T(&array)[N]))[N]; // NOLINT(readability/casting) #define arraysize(array) (sizeof(ArraySizeHelper(array))) -// ARRAYSIZE_UNSAFE performs essentially the same calculation as arraysize, -// but can be used on anonymous types or types defined inside -// functions. It's less safe than arraysize as it accepts some -// (although not all) pointers. Therefore, you should use arraysize -// whenever possible. -// -// The expression ARRAYSIZE_UNSAFE(a) is a compile-time constant of type -// size_t. -// -// ARRAYSIZE_UNSAFE catches a few type errors. If you see a compiler error -// -// "warning: division by zero in ..." -// -// when using ARRAYSIZE_UNSAFE, you are (wrongfully) giving it a pointer. -// You should only use ARRAYSIZE_UNSAFE on statically allocated arrays. -// -// The following comments are on the implementation details, and can -// be ignored by the users. -// -// ARRAYSIZE_UNSAFE(arr) works by inspecting sizeof(arr) (the # of bytes in -// the array) and sizeof(*(arr)) (the # of bytes in one array -// element). If the former is divisible by the latter, perhaps arr is -// indeed an array, in which case the division result is the # of -// elements in the array. Otherwise, arr cannot possibly be an array, -// and we generate a compiler error to prevent the code from -// compiling. -// -// Since the size of bool is implementation-defined, we need to cast -// !(sizeof(a) & sizeof(*(a))) to size_t in order to ensure the final -// result has type size_t. -// -// This macro is not perfect as it wrongfully accepts certain -// pointers, namely where the pointer size is divisible by the pointee -// size. Since all our code has to go through a 32-bit compiler, -// where a pointer is 4 bytes, this means all pointers to a type whose -// size is 3 or greater than 4 will be (righteously) rejected. -#define ARRAYSIZE_UNSAFE(a) \ - ((sizeof(a) / sizeof(*(a))) / \ - static_cast(!(sizeof(a) % sizeof(*(a))))) - #define SIZEOF_MEMBER(t, f) sizeof(std::declval().f) // Changing this definition will cause you a lot of pain. A majority of @@ -153,23 +113,23 @@ void UNUSED(const T&...) { // case 42: // ... // -// As shown in the example above, the FALLTHROUGH_INTENDED macro should be -// followed by a semicolon. It is designed to mimic control-flow statements -// like 'break;', so it can be placed in most places where 'break;' can, but -// only if there are no statements on the execution path between it and the -// next switch label. +// As shown in the example above, the FALLTHROUGH_INTENDED macro should be +// followed by a semicolon. It is designed to mimic control-flow statements +// like 'break;', so it can be placed in most places where 'break;' can, but +// only if there are no statements on the execution path between it and the +// next switch label. // -// When compiled with clang, the FALLTHROUGH_INTENDED macro is expanded to -// [[clang::fallthrough]] attribute, which is analysed when performing switch -// labels fall-through diagnostic ('-Wimplicit-fallthrough'). See clang -// documentation on language extensions for details: -// http://clang.llvm.org/docs/LanguageExtensions.html#clang__fallthrough +// When compiled with clang, the FALLTHROUGH_INTENDED macro is expanded to +// [[clang::fallthrough]] attribute, which is analysed when performing switch +// labels fall-through diagnostic ('-Wimplicit-fallthrough'). See clang +// documentation on language extensions for details: +// http://clang.llvm.org/docs/LanguageExtensions.html#clang__fallthrough // -// When used with unsupported compilers, the FALLTHROUGH_INTENDED macro has no -// effect on diagnostics. +// When used with unsupported compilers, the FALLTHROUGH_INTENDED macro has no +// effect on diagnostics. // -// In either case this macro has no effect on runtime behavior and performance -// of code. +// In either case this macro has no effect on runtime behavior and performance +// of code. #ifndef FALLTHROUGH_INTENDED #define FALLTHROUGH_INTENDED [[clang::fallthrough]] // NOLINT #endif