Rewriter : does not remove unused typedef statements and it lead to compile error

Hello. I'm struggling with DXR for applying to existing shader code bases.
In the below code, dxr remove PSOutput type as it does not used in entryPoint, but does not remove typedef statement.
It leads to compile error.

dxr.exe -remove-unused-functions -remove-unused-globals -E ps_main

struct VSOutput { };
struct PSOutput {};
typedef PSOutput PSPointOutput;

float4 ps_main(VSOutput psIn) { return float4(0.f, 0.f, 0.f, 1.f); }

Here is dxr output

struct VSOutput { };
typedef PSOutput PSPointOutput;

float4 ps_main(VSOutput psIn) { return float4(0.f, 0.f, 0.f, 1.f); }

Reproduce the issue with the provided shader snippet and the dxr.exe command using -remove-unused-functions, -remove-unused-globals, and -E ps_main. Trace the rewriter's unused-declaration handling, focusing on why the typedef remains after PSOutput is removed; done means the rewritten shader no longer contains the unused typedef and compiles successfully.