Source not included with emitNonSemanticShaderDebugSource

[spencer-lunarg]

If I have a simple shader like

#version 450
#extension GL_EXT_shader_8bit_storage: enable
#extension GL_EXT_shader_explicit_arithmetic_types_int8: enable
layout(push_constant) uniform PushConstant {
    int8_t x[4];
} data;

void main(){
    gl_Position = vec4(float(data.x[0]) * 0.0);
}

and run glslang -gVS I will see the OpString with all the source, but going

glslang::SpvOptions spv_options;
spv_options.emitNonSemanticShaderDebugSource = true;
glslang::GlslangToSpv(*program.getIntermediate(stage), spirv, &spv_options);

I only get

         %19 = OpString "// OpModuleProcessed client vulkan100
// OpModuleProcessed target-env vulkan1.0
// OpModuleProcessed entry-point main
#line 1
"