dxc internal error; invalid GEP with initialization of matrix in a struct

DXC throws an internal error when compiling this compute shader:

struct a {
  float b;
  float2x4 c;
};
struct d {
  a c;
};
struct e {
  d c[1];
  d f[1];
};

static e g = (e)0;

[numthreads(1, 1, 1)]
void main() {
  d h = g.f[0];
  return;
}

Steps to Reproduce

godbolt link

Actual Behavior

From the command line:

$ dxc -T cs_6_0 x.hlsl
error: cast<X>() argument of incompatible type!

Environment

• DXC version commit: 45018c752daf6dd0ad2d1a9b736e346268966279 (top of tree June 18 2024)
• Host Operating System: Linux

Initial investigation resulted in #6710 but that doesn't get to root cause.

Reproduce the failure with the shader shown in the issue using dxc -T cs_6_0 x.hlsl, then read the initial investigation in #6710 and trace the invalid cast<X>() diagnostic. Done means the reproduced shader no longer triggers the internal error when compiled with the stated DXC configuration.