Derived struct cannot be passed as `inout` parameter of base struct in function

[keptsecret]

Description
In trying out a workaround to this closed issue #8083, I found that passing the derived class to an inout parameter of the base class will fail to compile. See this code.

Steps to Reproduce
Tried to compile on godbolt with -E main -T cs_6_8 -HV 202x -spirv on DXC trunk.
It should be noted that without inout, it compiles fine. See code

Actual Behavior
I would expect it to compile fine just as it does without inout specifier.

Environment

• DXC version trunk (1.8.2505)
• Host Operating System Windows

[devshgraphicsprogramming]

The actual repro with inout is actually this https://godbolt.org/z/s4drrbfrx

The error is

<source>:15:7: note: candidate function [with F = float, cond = false, T = float] not viable: no known conversion from '__restrict base<float>' to 'derived<float, true>' for 1st argument

[devshgraphicsprogramming]

Also the base doesn't even need to be templated for the error to occur https://godbolt.org/z/q4Wo4q6zq

[devshgraphicsprogramming]

It actually doesn't depend on templates at all, https://godbolt.org/z/W5qrf6ooz

@keptsecret it would be good to change the title of the issue