‘is_trivially_copyable’ is not a member of ‘std’

c++ c++11 typetraits
user3156285 picture user3156285 · Aug 4, 2014 · Viewed 11k times · Source

My gcc version is 4.8.3 20140624. I can use is_pod, is_trivial, is_standard_layout, but fail when trying is_trivially_copyable, is_constructible and is_default_constructible, maybe more. The error message is 'xxx' is not a member of 'std'.

What's the problem here? Are they even supported by the current GCC? Thanks!

Answer

Kipton Barros picture Kipton Barros · Aug 4, 2015

As others mention, GCC versions < 5 do not support std::is_trivially_copyable from the C++11 standard.

Here is a hack to somewhat work around this limitation:

// workaround missing "is_trivially_copyable" in g++ < 5.0
#if __GNUG__ && __GNUC__ < 5
#define IS_TRIVIALLY_COPYABLE(T) __has_trivial_copy(T)
#else
#define IS_TRIVIALLY_COPYABLE(T) std::is_trivially_copyable<T>::value
#endif

For common cases, this hack might be enough to get your code working. Beware, however, subtle differences between GCC's __has_trivial_copy and std::is_trivially_copyable. Suggestions for improvement welcome.

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