Why does this HLSL pixel shader not compile?

I'm working on a ray tracing pixel shader and came across a weird error. I wrote the following code solely to generate the error, it's pointless but I can't figure out what's wrong with it.

float4 main(/*Any input*/) : SV_TARGET
{
    uint uints[2];
    float4 light[2];
    uints[0] = 0;
    uints[1] = 0;
    uint c = 1;
    [loop] while (c > 0) {
        if (uints[c] == 0)
            light[c - 1] = 0.0f;
        else
            light[c - 1] = 0.0f;
        c--;
        break;
    }
    return light[0];
}

When compiled with shader model 5_0 (with and without optimizations) I get the following error:

error MSB6006: "fxc.exe" exited with code -1073741819

Doing seemingly meaningless things to the code, like removing c--;, gets rid of the error. Can anyone figure out what this weird error comes from?

In my case it compiles if I remove the [loop] tag.

    // Compiling pixel shader
    ComPtr<ID3DBlob> pixelBlob = nullptr;
    ComPtr<ID3DBlob> pixelErrorBlob = nullptr;
    result = D3DCompile(pixelShaderByteCode.c_str(),
                        pixelShaderByteCode.length(),
                        nullptr,
                        nullptr,
                        nullptr,
                        "main", "ps_5_0",
                        compileFlags, 0,
                        pixelBlob.GetAddressOf(),
                        pixelErrorBlob.GetAddressOf());

float4 main(PixelInput input) : SV_TARGET
{
    uint uints[2];
    float4 light[2];
    uints[0] = 0;
    uints[1] = 0;
    uint c = 1;
    while (c > 0) {
        if (uints[c] == 0)
        light[c - 1] = 0.0f;
        else
        light[c - 1] = 0.0f;
        c--;
        break;
    }
    return light[0];
}