Cg Language incompatibility Desktop VS GLSL Android

Hi there,

today I came across a bug in one of my shaders. The following line caused the problem, but only on Android Mobile device:

 float3 side = step(3.0f, foo.xyz) * 3.0f;

The fix for this was the following:

 float3 side = step(float3(3,3,3), foo.xyz) * float3(3,3,3);

In the Unity3D Editor, even when GLES 2.0 emulation is enabled, the result is what I've expected. Each component of "side" contains 0 or 3 for each component of "foo" that is >= 3.

On mobile, each component of side contains 0 or 3 if foo.x is >= 3.

I do not get any "implicit truncation of vector type" warning in the log and also no warnings at all for any shader language in the shader properties.

I have searched the language specifications and found out that GLSL isn't capable to convert a single component float value to a vector type implicitly, or at least it isn't documented or I didn't find it.

But Cg is, which would mean that the generated code for HLSL/GLSL is wrong, but why only on mobile? According to the Cg spec, the first code portion should be okay, the first parameter of step() should be widened to be a float3 and the last multiplication should become a float3, too.

So who is wrong here? Did I misunderstand something, is there a bug in Cg or in Unity3D? Should I file a bug report with an example project?

Best,

Nils