c++ - 'va_start' used in function with fixed args error -

my nullpointcheck function:

template<typename t, typename... args> bool __nullpointcheck(t first, args... args) {     bool ret = true;     va_list vl;     auto n = sizeof...(args);     va_start(vl, n);     (auto = 0; <= n; ++i)     {         auto p = va_arg(vl, t);         if (!p)         {             ret = false;         }     }     va_end(vl);     return ret; } 

but i'm getting ndk build error follows:

'va_start' used in function fixed args va_start(vl, n); 

when change second param in va_start first follows:

va_start(vl, first); 

ndk-build export error follows:

     'va_start' used in function fixed args     va_start(vl, first);     ^ e:/android_home/android-ndk-r10c/toolchains/llvm-3.5/prebuilt/windows-x86_64/bin \..\lib\clang\3.5\include\stdarg.h:33:29: note: expanded macro 'va_start' #define va_start(ap, param) __builtin_va_start(ap, param) 

there no errors in vs2013, code can's pass ndk-build stage

va_start etc. can used in function prototype ends in ...); . different parameter pack. code uses parameter pack. syntax using parameter packs different syntax variadic functions.

i assuming function should return true if , if arguments non-null pointers. 1 way implement function be:

inline constexpr bool nullpointcheck() { return true; }  template<typename t, typename... args> constexpr bool nullpointcheck(t&& first, args&&... args) {     return first && nullpointcheck(args...); } 

rontgen's answer good.

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you can use function check if arbitrary argument list true. used universal references copies not made of arguments; makes no difference pointers may make difference more complicated types.

to limit function accept pointers, change t&& t *. (leave args&& is). if want accept literal nullptr need overload:

inline constexpr bool nullpointcheck(std::nullptr_t) { return false; } 

because nullptr not deduce t *.