### Compilation failed:

error: 1: 'main' must return: 'vec4', 'float4', or 'half4'
void main() {
^^^^^^^^^^^
error: 5: name 'sk_Caps' is reserved
    if (sk_Caps.floatIs32Bits) x = 1;
        ^^^^^^^^^^^^^^^^^^^^^
error: 6: name 'sk_Caps' is reserved
    if (sk_Caps.integerSupport) y = 1;
        ^^^^^^^^^^^^^^^^^^^^^^
error: 7: name 'sk_Caps' is reserved
    if (sk_Caps.builtinDeterminantSupport) z = 1;
        ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
error: 8: unknown identifier 'sk_FragColor'
    sk_FragColor.rgb = half3(x, y, z);
    ^^^^^^^^^^^^
5 errors