uniform half4 colorGreen, colorRed;

half4 main(float2 coords) {
    // Two variables, both used.
    half sumA = 0, sumB = 0;
    for (half a = 0, b = 10; a < 10 && b > 0; ++a, --b) {
        sumA += a;
        sumB += b;
    }
    if (sumA != 45 || sumB != 55) {
        return colorRed;
    }

    // Two variables, one dead
    int sumC = 0;
    for (int c = 0, d = 0; c < 10; ++c) {
        sumC += c;
    }
    if (sumC != 45) {
        return colorRed;
    }

    // Three variables, all used, some array-typed
    float sumE = 0.0;
    for (float d[2] = float[2](0, 10), e[4] = float[4](1,2,3,4), f = 0; d[0] < d[1]; ++d[0]) {
        sumE += half(e[0]);
    }
    if (sumE != 10) {
        return colorRed;
    }

    // Four variables, all dead
    for (half4 x, y, z, w;; ) break;

    // Just referencing a variable instead of declaring it--legal, if not meaningful.
    for (sumA;; ) return colorGreen;
}