From a766d27447aa0fcf69334c0467d9b1124892e180 Mon Sep 17 00:00:00 2001
From: Ellie Hermaszewska <ellieh@nvidia.com>
Date: Thu, 4 Sep 2025 04:05:26 +0800
Subject: Diagnose on structured buffers containing resources (#8222)

closes https://github.com/shader-slang/slang/issues/3313
---
 source/slang/slang-check-decl.cpp | 105 ++++++++++++++++++++++++++++++++++++++
 1 file changed, 105 insertions(+)

(limited to 'source/slang/slang-check-decl.cpp')

diff --git a/source/slang/slang-check-decl.cpp b/source/slang/slang-check-decl.cpp
index e59cf6ad5..4711eaddd 100644
--- a/source/slang/slang-check-decl.cpp
+++ b/source/slang/slang-check-decl.cpp
@@ -2698,6 +2698,8 @@ static Expr* constructDefaultInitExprForType(SemanticsVisitor* visitor, VarDeclB
     }
 }
 
+void validateStructuredBufferElementType(SemanticsVisitor* visitor, VarDeclBase* varDecl);
+
 void SemanticsDeclBodyVisitor::checkVarDeclCommon(VarDeclBase* varDecl)
 {
     DiagnoseIsAllowedInitExpr(varDecl, getSink());
@@ -2892,6 +2894,9 @@ void SemanticsDeclBodyVisitor::checkVarDeclCommon(VarDeclBase* varDecl)
             }
         }
     }
+
+    validateStructuredBufferElementType(this, varDecl);
+
     bool isGlobalOrLocalVar = !isGlobalShaderParameter(varDecl) && !as<ParamDecl>(varDecl) &&
                               (!parentDecl || isEffectivelyStatic(varDecl));
     if (isGlobalOrLocalVar)
@@ -15018,6 +15023,106 @@ bool isOpaqueHandleType(Type* type)
     return false;
 }
 
+bool containsRecursiveTypeImpl(SemanticsVisitor* visitor, Type* type, HashSet<Decl*>& currentPath)
+{
+    // Skip modified types (const, etc.)
+    while (auto modifiedType = as<ModifiedType>(type))
+        type = modifiedType->getBase();
+
+    // Check if this is a StructuredBuffer type and look inside it
+    if (auto structuredBufferType = as<HLSLStructuredBufferTypeBase>(type))
+    {
+        return containsRecursiveTypeImpl(
+            visitor,
+            structuredBufferType->getElementType(),
+            currentPath);
+    }
+
+    // Check if this is an array type and look inside it
+    if (auto arrayType = as<ArrayExpressionType>(type))
+    {
+        return containsRecursiveTypeImpl(visitor, arrayType->getElementType(), currentPath);
+    }
+
+    if (auto declRefType = as<DeclRefType>(type))
+    {
+        auto typeDecl = declRefType->getDeclRef().getDecl();
+
+        // Check global cache first - if we've already fully analyzed this type, use that result
+        auto shared = visitor->getShared();
+        if (auto cachedResult = shared->m_typeContainsRecursionCache.tryGetValue(typeDecl))
+        {
+            return *cachedResult;
+        }
+
+        // If we're currently exploring this type, we found a cycle!
+        if (currentPath.contains(typeDecl))
+        {
+            return true;
+        }
+
+        // Add to current exploration path
+        currentPath.add(typeDecl);
+
+        bool hasRecursion = false;
+
+        // Check members if it's an aggregate type
+        if (auto aggTypeDecl = declRefType->getDeclRef().as<AggTypeDecl>())
+        {
+            for (auto member : aggTypeDecl.getDecl()->getMembersOfType<VarDeclBase>())
+            {
+                if (isEffectivelyStatic(member))
+                    continue;
+
+                if (containsRecursiveTypeImpl(visitor, member->getType(), currentPath))
+                {
+                    hasRecursion = true;
+                    break;
+                }
+            }
+        }
+
+        // Remove from current exploration path
+        currentPath.remove(typeDecl);
+
+        // Cache the result globally
+        shared->m_typeContainsRecursionCache[typeDecl] = hasRecursion;
+
+        return hasRecursion;
+    }
+
+    return false;
+}
+
+bool containsRecursiveType(SemanticsVisitor* visitor, Type* type)
+{
+    HashSet<Decl*> currentPath;
+    return containsRecursiveTypeImpl(visitor, type, currentPath);
+}
+
+void validateStructuredBufferElementType(SemanticsVisitor* visitor, VarDeclBase* varDecl)
+{
+    auto type = unwrapArrayType(varDecl->getType());
+
+    // Check if this is a StructuredBuffer type
+    auto structuredBufferType = as<HLSLStructuredBufferTypeBase>(type);
+
+    if (!structuredBufferType)
+        return;
+
+    // Get the element type
+    auto elementType = structuredBufferType->getElementType();
+
+    // Check if the element type contains recursive references
+    if (containsRecursiveType(visitor, elementType))
+    {
+        visitor->getSink()->diagnose(
+            varDecl->loc,
+            Diagnostics::recursiveTypesFoundInStructuredBuffer,
+            elementType);
+    }
+}
+
 void diagnoseMissingCapabilityProvenance(
     CompilerOptionSet& optionSet,
     DiagnosticSink* sink,
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