unity_StereoEyeIndex broken in 5.6.0f3 or just not behaving as expected?

Graphics Shaders & Materials
1

My situation:
VR-related custom shader. Various tweaks in the vert function to select from an over/under texture to display to each eye, various other behaviors. Shader logic in general is fine. I get what I expect from everything but the following:

This is always true (and obviously shouldn’t be):
if (unity_StereoEyeIndex == 0) {
// Logic
}

This works as expected:
if (unity_CameraProjection[0][2] < 0) {
// Logic
}

Tested with GoogleVR SDK, both Daydream and Cardboard.

2

unity_StereoEyeIndex should only be effected in single-pass stereo mode, and as far as I know, only GearVR support that offically on mobile VR platform.

3

For sure won’t work for GoogleVR or Cardboard, but should work with Daydream if Single pass stereo is enabled. It might only be working in the latest 5.6 / 2017 builds though.