performing layout generation after linking causes non local structs to have no layout information

[expipiplus1]

Consider the following

main.slang:

public interface IFoo
{
    public float4 getFoo();
};
public extern struct S : IFoo;

[shader("vertex")]
float4 vs_main(S params) : SV_Position
{
    return params.getFoo();
}

foo.slang:

import main;

export public struct S : IFoo
{
    public float4 getFoo() { return this.foo; }

    float4 foo;
}

When these are compiled and linked, we generate the layout information for S before linking with the definition of S in foo.slang

This is the diff between a good version, in which the definition for S is available, and the bad version above. Observe how the details of the struct layout are missign

11161,11164c11111
< let  %10        : Void  = varLayout(%11, %12, %6)
< let  %11        : Void  = structTypeLayout(%13, %14)
< let  %14        : Void  = fieldLayout(%foo, %15)
< let  %15        : Void  = varLayout(%16, %12, %6)
---
> let  %10        : Void  = varLayout(%11, %6)
11166,11168c11113
< let  %12        : Void  = offset(5 : Int, 0 : Int)
< let  %16        : Void  = typeLayout(%13)
< let  %13        : Void  = size(5 : Int, 1 : Int)
---
> let  %11        : Void  = structTypeLayout
11190c11135
< let  %17        : rtti_type     = rtti_object(%S)
---
> let  %12        : rtti_type     = rtti_object(%S)
11199c11144
< block %18(
---
> block %13(
11202,11203c11147,11148
<         let  %19        : Vec(Float, 4 : Int)   = get_field(%this, %foo)
<         return_val(%19)
---
>         let  %14        : Vec(Float, 4 : Int)   = get_field(%this, %foo)
>         return_val(%14)
11213c11158
< block %20(
---
> block %15(
11217,11219c11162,11164
<         let  %21        : %S    = load(%params)
<         let  %22        : Vec(Float, 4 : Int)   = call %Sx5FgetFoo(%21)
<         return_val(%22)
---
>         let  %16        : %S    = load(%params)
>         let  %17        : Vec(Float, 4 : Int)   = call %Sx5FgetFoo(%16)
>         return_val(%17)
11222,11243c11167
< #version 450
< layout(row_major) uniform;
< layout(row_major) buffer;
< struct S_0
< {
<     vec4 foo_0;
< };
<
< vec4 S_getFoo_0(S_0 this_0)
< {
<     return this_0.foo_0;
< }
<
< layout(location = 0)
< in vec4 params_foo_0;
<
< void main()
< {
<     S_0 _S1 = { params_foo_0 };
<     gl_Position = S_getFoo_0(_S1);
<     return;
< }
---
> (0): error 99999: Slang compilation aborted due to an exception of N5Slang13InternalErrorE: assert failure: structTypeLayout->getFieldCount() == structFieldCount

[bmillsNV]

Closing this. It's the root cause of #5994