tests/sksl/shared/InterpolantOut.glsl

layout (location = 0) out float defaultVarying;
layout (location = 1) noperspective out float linearVarying;
layout (location = 2) flat out float flatVarying;
void main() {
    defaultVarying = 1.0;
    linearVarying = 2.0;
    flatVarying = 3.0;
}