casting to floating point unimplemented #1675

When compiling for Spirv:
With:

float4 a[6];
float b[24] = (float[24])a;

Gives the error:
casting to floating point unimplemented.

Also with:
float4 a[4];
float b= ((float[16])a)[0];

Gives the error:
casting to floating point unimplemented.

Compiles fine in glslc.