template<int> struct X {}; constexpr auto f() { int const N = std::is_constant_evaluated() ? 13 : 17; X<N> x1; X<std::is_constant_evaluated() ? 13 : 17> x2; } 我们希望上面的x1和x2有着相同的类型,但是N的初始化并不要求一个常量值(请注意:const只是表明一个不可变值,不是...
inty;constinta=std::is_constant_evaluated()?y:1;// 试探性常量求值失败,常量求值被舍弃。// 变量 a 动态初始化为 1constintb=std::is_constant_evaluated()?2:y;// 常量求值(std::is_constant_evaluation() == true)成功。// 变量 b 静态初始化为 2 ...
例如，GCC在is_constant_evaluated之前使用__builtin_constant_p。演示：GCC 6.1 running C++17 ...
constexpr int Fn1() { if constexpr (std::is_constant_evaluated()) return 0; else return 1; } constexpr int Fn2() { if (std::is_constant_evaluated()) return 0; else return 1; } int main() { constexpr int test1 = Fn1(); // Evaluates to 0 int test2 = Fn1(); // Evalua...
__cpp_lib_is_constant_evaluated201811L(C++20)std::is_constant_evaluated Example Run this code #include <cmath>#include <iostream>#include <type_traits>constexprdoublepower(doubleb,intx){if(std::is_constant_evaluated()&&!(b==0.0&&x<0)){// A constant-evaluation context: Use a constexpr...
__builtin_is_constant_evaluated是用于在clang和gcc标准库中实现std::is_constant_evaluated的内置组件。例如: if (__builtin_is_constant_evaluated()) else { int我知道这将使__builtin_is_constant_evaluated()实现的返回值得到定义,因为优化在不同编译器之间有所不同。但是,只有当两条路径具有相 浏览0提问...
aATXPWR ATXPWR[translate] ait is repaired regularly 它通常被修理[translate] aidont know idont知道[translate] aOne instance in which this form arises is when an equilibration rate constant is evaluated. 这个形式出现的一个事例是平衡率常数被评估。[translate]...
constexpr int foo(int s) { if (std::is_constant_evaluated()) // note: not "if constexpr" /* evaluated at compile time */; else /* evaluated at run time */; } Note that here the ordinary if is used instead of if constexpr. If you use if constexpr, then t...
integer constant not in range of enumerated type %0 -Watomic-property-with-user-defined-accessor writable atomic property %0 cannot pair a synthesized %select{getter|setter}1 with a user defined %select{getter|setter}2 -Wattributes unknown attribute %0 ignored -Wauto-var-id 'auto' deduced as...
A Const statement does not properly initialize a constant, or an array declaration uses a variable to specify the number of elements.Error ID: BC30059To correct this errorIf the declaration is a Const statement, check to make sure the constant is initialized with a literal, a previously ...