From 282da4ac94d60d3244f4d72085e66fb82cf5abd8 Mon Sep 17 00:00:00 2001
From: ArielG-NV <159081215+ArielG-NV@users.noreply.github.com>
Date: Tue, 16 Apr 2024 22:01:06 -0400
Subject: Fix for unscoped enums circular reference causing an error, #3959
 (#3962)

---
 source/slang/slang-check-decl.cpp                  | 11 ++++++--
 source/slang/slang-lookup.cpp                      |  4 +--
 .../enums/unscoped-enum-explicit-type.slang        | 32 ++++++++++++++++++++++
 3 files changed, 43 insertions(+), 4 deletions(-)
 create mode 100644 tests/language-feature/enums/unscoped-enum-explicit-type.slang

diff --git a/source/slang/slang-check-decl.cpp b/source/slang/slang-check-decl.cpp
index d35502235..131d30d98 100644
--- a/source/slang/slang-check-decl.cpp
+++ b/source/slang/slang-check-decl.cpp
@@ -2380,8 +2380,15 @@ namespace Slang
     {
         // check the type being inherited from
         auto base = inheritanceDecl->base;
-        CheckConstraintSubType(base);
-        base = TranslateTypeNode(base);
+        Decl* toExclude = nullptr;
+        Decl* parent = getParentDecl(inheritanceDecl);
+        // We exclude in the case that a circular reference is possible. This is when a parent is a transparent decl.
+        // If we just blanket "block" all ensure's of a parent a generic may fail when trying to fetch a parent
+        if (parent->findModifier<TransparentModifier>())
+            toExclude = parent;
+        SemanticsDeclVisitorBase baseVistor(this->withDeclToExcludeFromLookup(toExclude));
+        baseVistor.CheckConstraintSubType(base);
+        base = baseVistor.TranslateTypeNode(base);
         inheritanceDecl->base = base;
 
         // Note: we do not check whether the type being inherited from
diff --git a/source/slang/slang-lookup.cpp b/source/slang/slang-lookup.cpp
index 2be9d29e8..9c8b2fa0b 100644
--- a/source/slang/slang-lookup.cpp
+++ b/source/slang/slang-lookup.cpp
@@ -224,13 +224,13 @@ static void _lookUpDirectAndTransparentMembers(
         }
     }
 
-    // TODO(tfoley): should we look up in the transparent decls
-    // if we already has a hit in the current container?
     for(auto transparentInfo : containerDecl->getTransparentMembers())
     {
         // The reference to the transparent member should use the same
         // path as we used in referring to its parent.
         DeclRef<Decl> transparentMemberDeclRef = astBuilder->getMemberDeclRef(parentDeclRef, transparentInfo.decl);
+        if (transparentMemberDeclRef.getDecl() == request.declToExclude)
+            continue;
 
         // We need to leave a breadcrumb so that we know that the result
         // of lookup involves a member lookup step here
diff --git a/tests/language-feature/enums/unscoped-enum-explicit-type.slang b/tests/language-feature/enums/unscoped-enum-explicit-type.slang
new file mode 100644
index 000000000..aefbf8449
--- /dev/null
+++ b/tests/language-feature/enums/unscoped-enum-explicit-type.slang
@@ -0,0 +1,32 @@
+//TEST(compute):COMPARE_COMPUTE(filecheck-buffer=CHECK): -shaderobj
+
+//TEST_INPUT:ubuffer(data=[0 0], stride=4):out,name=outputBuffer
+RWStructuredBuffer<uint32_t> outputBuffer;
+
+[UnscopedEnum]
+enum unscopedEnum : uint32_t
+{
+    kEnumVal1 = 5,
+    kEnumVal2 = 6,
+};
+
+struct structWithEnumVal
+{
+    unscopedEnum val;
+};
+
+void takeInToWriteFruit(unscopedEnum inData, structWithEnumVal inData2)
+{
+    outputBuffer[0] = inData;
+    outputBuffer[1] = inData2.val;
+}
+
+[numthreads(1,1,1)]
+void computeMain()
+{
+    // CHECK: 5
+    // CHECK: 6
+    structWithEnumVal enumVal;
+    enumVal.val = kEnumVal2;
+    takeInToWriteFruit(kEnumVal1, enumVal);
+}
\ No newline at end of file
-- 
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