Non-consistent implicit function template specializations

[Ali Çehreli]

On 8/18/21 4:10 AM, Rekel wrote:

 >>   isArray!T && (isArray!(ElementType!T))
 >
 > I tried looking into how isArray is defined. Like, does being able to
 > index mean it's an array, or are these only static &/or dynamic arrays?

The definitions are in phobos/std/traits.d

   enum bool isArray(T) = isStaticArray!T || isDynamicArray!T;

isStaticArray uses the compiler's __traits feature:

   enum bool isStaticArray(T) = __traits(isStaticArray, T);

isDynamicArray uses the is expression but apparently has some history:

template isDynamicArray(T)
{
     static if (is(T == U[], U))
         enum bool isDynamicArray = true;
     else static if (is(T U == enum))
         // BUG: isDynamicArray / isStaticArray considers enums
         // with appropriate base types as dynamic/static arrays
         // Retain old behaviour for now, see
         // https://github.com/dlang/phobos/pull/7574
         enum bool isDynamicArray = isDynamicArray!U;
     else
         enum bool isDynamicArray = false;
}

Ali