From ff7c46a11787ca6ecebf0a224772a41efef33fc0 Mon Sep 17 00:00:00 2001
From: Yong He <yonghe@outlook.com>
Date: Sun, 5 Nov 2017 05:49:42 -0500
Subject: small cleanups

---
 source/slang/check.cpp       | 2 ++
 source/slang/ir.cpp          | 4 +++-
 source/slang/lower-to-ir.cpp | 7 +++++--
 3 files changed, 10 insertions(+), 3 deletions(-)

diff --git a/source/slang/check.cpp b/source/slang/check.cpp
index 79a4f28cf..ed2ed4a1b 100644
--- a/source/slang/check.cpp
+++ b/source/slang/check.cpp
@@ -1662,6 +1662,8 @@ namespace Slang
                             return false;
 
                         auto structTypeDecl = declRefType->declRef.getDecl()->As<AggTypeDecl>();
+                        if (!structTypeDecl)
+                            return false;
                         //TODO: What do we do if type is a generic specialization?
                         // i.e. if the struct defines typedef Generic<float> T; 
                         // how to check if T satisfies the associatedtype constraints?
diff --git a/source/slang/ir.cpp b/source/slang/ir.cpp
index 04569771a..ab961a159 100644
--- a/source/slang/ir.cpp
+++ b/source/slang/ir.cpp
@@ -562,11 +562,13 @@ namespace Slang
 
     IRValue * IRBuilder::getTypeVal(IRType * type)
     {
-        auto irValue = createValue<IRDeclRef>(
+        auto irValue = createValue<IRValue>(
             this,
             kIROp_TypeType,
             nullptr);
         irValue->type = type;
+        if (auto typetype = dynamic_cast<TypeType*>(type))
+            irValue->type = typetype->type;
         return irValue;
     }
 
diff --git a/source/slang/lower-to-ir.cpp b/source/slang/lower-to-ir.cpp
index be91b9d3d..2672c5698 100644
--- a/source/slang/lower-to-ir.cpp
+++ b/source/slang/lower-to-ir.cpp
@@ -2311,8 +2311,11 @@ struct DeclLoweringVisitor : DeclVisitor<DeclLoweringVisitor, LoweredValInfo>
             ensureDecl(context, inheritanceDecl);
         }
 
-        // For now, we don't have an IR-level representation
-        // for the type itself.
+        // TODO: we currently store a Decl* in the witness table, which causes this function
+        // being invoked to translate the witness table entry into an IRValue.
+        // We should really allow a witness table entry to represent a type and not having to
+        // construct the type here. The current implementation will not work when the struct type
+        // is defined in a generic parent (we lose the environmental substitutions).
         return LoweredValInfo::simple(context->irBuilder->getTypeVal(DeclRefType::Create(context->getSession(), 
             DeclRef<Decl>(decl, nullptr))));
     }
-- 
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