Clang 接受此代码,但 GCC 拒绝它:
class Foo {
public:
static constexpr double kVal = 0.25f;
};
const double Foo::kVal;
(使用 clang 3.0 和 g++ 4.6.3)
~$ clang++ foo.cc -std=c++11 -c
[ok]
~$ g++ foo.cc -std=c++0x -c
foo.cc:6:19: error: redeclaration ‘Foo::kVal’ differs in ‘constexpr’
foo.cc:3:34: error: from previous declaration ‘Foo::kVal’
foo.cc:6:19: error: declaration of ‘constexpr const double Foo::kVal’ outside of class is not definition [-fpermissive]
哪种解释是正确的?