Resolve 'extern' types during type layout generation if possible (#6450)

* Resolve 'extern' types during type layout generation if possible

Closes https://github.com/shader-slang/slang/issues/5994
Closes https://github.com/shader-slang/slang/issues/6437

* format code

---------

Co-authored-by: slangbot <186143334+slangbot@users.noreply.github.com>
Co-authored-by: Yong He <yonghe@outlook.com>

1 files changed, 7 insertions, 0 deletions

diff --git a/source/slang/slang-parameter-binding.cpp b/source/slang/slang-parameter-binding.cpp
index 0e47ff56d..86d76fc6d 100644
--- a/source/slang/slang-parameter-binding.cpp
+++ b/source/slang/slang-parameter-binding.cpp
@@ -2382,7 +2382,14 @@ static RefPtr<TypeLayout> processEntryPointVaryingParameter(
     // otherwise they will include all of the above cases...
     else if (auto declRefType = as<DeclRefType>(type))
     {
+        // If we are trying to get the layout of some extern type, do our best
+        // to look it up in other loaded modules and generate the type layout
+        // based on that.
+        declRefType = context->layoutContext.lookupExternDeclRefType(declRefType);
+
         auto declRef = declRefType->getDeclRef();
+
+
         if (auto structDeclRef = declRef.as<StructDecl>())
         {
             RefPtr<StructTypeLayout> structLayout = new StructTypeLayout();