Can not get struct member location from reflection

The shader is from OpenGL4.6 CTS, the uniform data type is struct S, the uniform variable 's' is assigned with location 0 at link time, after build the reflection, all the locations of s.a, s.b, and s.c are 0xfff, but I expect I can get the real location from reflection(s.a is expected to be 0, s.b[0] is expected 1, and s.c is expected to be 4), how can I get the correct location for the struct member? I saw the struct was blown up to the simple items in TReflectionTraverser::blowUpActiveAggregate(), but the location information was lost when the struct is expanded to simple items.

Thanks

##########################
#version 330
in highp vec4 a_position;
in highp vec4 a_coords;
out mediump vec4 v_color;
uniform int ui_one;

struct S {
mediump float a;
mediump float b[3];
int c;
};
uniform S s;

void main (void)
{
v_color = vec4(s.a, s.b[0], s.b[1], s.c);
gl_Position = a_position;
}
##########################

Reproduce the OpenGL 4.6 CTS shader and inspect reflection handling around TReflectionTraverser::blowUpActiveAggregate(), where the issue reports that struct-member locations are lost. Trace how s.a, s.b[0], and s.c are expanded and represented, then verify that reflection reports locations 0, 1, and 4 for the provided shader.

Written by the indexing model from the issue text.