3 files changed, 68 insertions, 2 deletions
diff --git a/source/slang/syntax.cpp b/source/slang/syntax.cpp
index ca66e2110..c49cd3648 100644
--- a/source/slang/syntax.cpp
+++ b/source/slang/syntax.cpp
@@ -505,9 +505,18 @@ void Type::accept(IValVisitor* visitor, void* extra)
                         if (aggTypeDeclRef.getDecl()->memberDictionary.TryGetValue(assocTypeDecl->getName(), targetType))
                         {
                             if (auto typeDefDecl = dynamic_cast<TypeDefDecl*>(targetType))
-                                return typeDefDecl->type.type;
+                            {
+                                DeclRef<TypeDefDecl> targetTypeDeclRef(typeDefDecl, aggTypeDeclRef.substitutions);
+                                return GetType(targetTypeDeclRef);
+                            }
+                            else if (auto targetAggType = dynamic_cast<AggTypeDecl*>(targetType))
+                            {
+                                return DeclRefType::Create(getSession(), DeclRef<Decl>(targetAggType, aggTypeDeclRef.substitutions));
+                            }
                             else
-                                return DeclRefType::Create(getSession(), DeclRef<Decl>(targetType, aggTypeDeclRef.substitutions));
+                            {
+                                SLANG_UNIMPLEMENTED_X("unknown assoctype implementation type.");
+                            }
                         }
                     }
                 }
diff --git a/tests/compute/assoctype-func-param.slang b/tests/compute/assoctype-func-param.slang
new file mode 100644
index 000000000..63acfb23a
--- /dev/null
+++ b/tests/compute/assoctype-func-param.slang
@@ -0,0 +1,53 @@
+//TEST(compute):COMPARE_COMPUTE:-xslang -use-ir
+//TEST_INPUT:ubuffer(data=[0 0 0 0], stride=4):dxbinding(0),glbinding(0),out
+
+// Test type checking of associatedtype and typedef
+
+RWStructuredBuffer<float> outputBuffer;
+
+interface IBase
+{
+    associatedtype SubTypeT;
+    associatedtype RetT;
+    RetT getVal(SubTypeT t);
+    SubTypeT setVal(RetT v);
+}
+
+struct SubType<T>
+{
+    T x;
+};
+
+struct GenStruct<T> : IBase
+{
+    typedef T RetT;
+    typedef SubType<RetT> SubTypeT;
+    SubTypeT setVal(T val)
+    {
+        SubTypeT rs;
+        rs.x = val;
+        return rs;
+    }
+    T getVal(SubTypeT v)
+    {
+        return v.x;
+    }
+};
+
+U.RetT test<U:IBase>(U.RetT val)
+{
+    U obj;
+    U.SubTypeT sb = obj.setVal(val);
+    return obj.getVal(sb);
+}
+
+
+[numthreads(4, 1, 1)]
+void computeMain(uint3 dispatchThreadID : SV_DispatchThreadID)
+{
+    uint tid = dispatchThreadID.x;
+    float inVal = float(tid);
+    /* wrong error message for the following line */
+    float outVal = test<GenStruct<float> >(inVal);
+    outputBuffer[tid] = outVal.x;
+}
+\ No newline at end of file
diff --git a/tests/compute/assoctype-func-param.slang.expected.txt b/tests/compute/assoctype-func-param.slang.expected.txt
new file mode 100644
index 000000000..98798bd61
--- /dev/null
+++ b/tests/compute/assoctype-func-param.slang.expected.txt
@@ -0,0 +1,4 @@
+0
+3F800000
+40000000
+40400000
+\ No newline at end of file