__is_scalar
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Category
Type Trait Functions
Syntax
bool __is_scalar( typename T )
Returns true if and only if T is a scalar type.
Scalar type is defined in Section 3.9 p10 of the Working Draft.
Essentially:
__is_arithmetic( T ) || __is_enumeration(T) ||
__is_pointer(T) || __is_member_pointer(T)
Scalar types have a built in meaning for operator < as well as operator ==. Therefore, __closure is not a scalar type.