Filter lookup results from interfaces in visitMemberExpr.

Fixes shader-slang#1377

Author: csyonghe

source/slang/slang-check-expr.cpp

@@ -1826,10 +1826,38 @@ namespace Slang
         //
         expr->baseExpression = maybeOpenExistential(expr->baseExpression);
 
-        // TODO: Handle the case of an overloaded base expression
+        // Handle the case of an overloaded base expression
         // here, in case we can use the name of the member to
         // disambiguate which of the candidates is meant, or if
         // we can return an overloaded result.
+        if (auto overloadedExpr = as<OverloadedExpr>(expr->baseExpression))
+        {
+            if (overloadedExpr->base)
+            {
+                // If a member (dynamic or static) lookup result contains both the actual definition
+                // and the interface definition obtained from inheritance, we want to filter out
+                // the interface definitions.
+                LookupResult filteredLookupResult;
+                for (auto lookupResult : overloadedExpr->lookupResult2)
+                {
+                    bool shouldRemove = false;
+                    if (lookupResult.declRef.getParent().as<InterfaceDecl>())
+                        shouldRemove = true;
+                    if (!shouldRemove)
+                    {
+                        filteredLookupResult.items.add(lookupResult);
+                    }
+                }
+                if (filteredLookupResult.items.getCount() == 1)
+                    filteredLookupResult.item = filteredLookupResult.items.getFirst();
+                expr->baseExpression = createLookupResultExpr(
+                    expr->name,
+                    filteredLookupResult,
+                    overloadedExpr->base,
+                    overloadedExpr->loc);
+            }
+            // TODO: handle other cases of OverloadedExpr that need filtering.
+        }
 
         auto & baseType = expr->baseExpression->type;
 

tests/compute/assoctype-lookup.slang

@@ -0,0 +1,58 @@
+// assoctype-nested.slang
+
+// Confirm that an associated type can be correctly looked up.
+
+//TEST(compute):COMPARE_COMPUTE_EX:-slang -compute -cpu
+//TEST(compute):COMPARE_COMPUTE_EX:-slang -compute
+//TEST(compute):COMPARE_COMPUTE_EX:-slang -compute -dx12
+//TEST(compute, vulkan):COMPARE_COMPUTE_EX:-vk -compute
+
+interface IBoneWeightSet
+{
+    associatedtype PackedType;
+};
+
+struct StandardBoneWeightSet : IBoneWeightSet
+{
+    struct PackedType
+    {
+        uint boneIds : BONEIDS;
+        uint boneWeights : BONEWEIGHTS;
+    };
+    PackedType field;
+};
+
+interface IVertexFormat
+{
+    associatedtype BoneWeightSet : IBoneWeightSet;
+};
+
+struct VertexFormat<TBoneWeightSet : IBoneWeightSet> : IVertexFormat
+{
+    typedef TBoneWeightSet BoneWeightSet;
+    TBoneWeightSet.PackedType weightSet;
+};
+
+struct OutputType
+{
+    VertexFormat<StandardBoneWeightSet>.BoneWeightSet.PackedType field;
+};
+
+int test(int val)
+{
+    OutputType rs;
+    rs.field.boneIds = 256;
+    return rs.field.boneIds;
+}
+
+//TEST_INPUT:ubuffer(data=[0 0 0 0], stride=4):out,name=gOutputBuffer
+RWStructuredBuffer<int> gOutputBuffer;
+
+[numthreads(4, 1, 1)]
+void computeMain(uint3 dispatchThreadID : SV_DispatchThreadID)
+{
+    uint tid = dispatchThreadID.x;
+    int inputVal = tid;
+    int outputVal = test(inputVal);
+    gOutputBuffer[tid] = outputVal;
+}

tests/compute/assoctype-lookup.slang.expected.txt

@@ -0,0 +1,4 @@
+100
+100
+100
+100