3 files changed, 66 insertions, 4 deletions

diff --git a/source/slang/slang-check-conversion.cpp b/source/slang/slang-check-conversion.cpp
index 8f2ea3ca7..705da89e3 100644
--- a/source/slang/slang-check-conversion.cpp
+++ b/source/slang/slang-check-conversion.cpp
@@ -97,7 +97,17 @@ bool SemanticsVisitor::shouldUseInitializerDirectly(Type* toType, Expr* fromExpr
     // we want to check for is whether a direct initialization
     // is possible (a type conversion exists).
     //
-    return canCoerce(toType, fromExpr->type, fromExpr);
+    ConversionCost cost;
+    if (canCoerce(toType, fromExpr->type, fromExpr, &cost))
+    {
+        if (cost >= kConversionCost_Explicit)
+        {
+            return false;
+        }
+        return true;
+    }
+
+    return false;
 }
 
 bool SemanticsVisitor::_readValueFromInitializerList(
@@ -526,6 +536,19 @@ bool SemanticsVisitor::_readAggregateValueFromInitializerList(
         }
         else
         {
+            auto isLinkTimeVal =
+                as<TypeCastIntVal>(toElementCount) || as<DeclRefIntVal>(toElementCount) ||
+                as<PolynomialIntVal>(toElementCount) || as<FuncCallIntVal>(toElementType);
+            if (isLinkTimeVal)
+            {
+                auto defaultConstructExpr = m_astBuilder->create<DefaultConstructExpr>();
+                defaultConstructExpr->loc = fromInitializerListExpr->loc;
+                defaultConstructExpr->type = QualType(toType);
+
+                *outToExpr = defaultConstructExpr;
+                return true;
+            }
+
             // We don't know the element count statically,
             // so what are we supposed to be doing?
             //
@@ -702,12 +725,26 @@ bool SemanticsVisitor::_readAggregateValueFromInitializerList(
         auto toRowType =
             createVectorType(toMatrixType->getElementType(), toMatrixType->getColumnCount());
 
-        if (auto constRowCount = as<ConstantIntVal>(toMatrixType->getRowCount()))
+        auto rowCountIntVal = toMatrixType->getRowCount();
+        if (auto constRowCount = as<ConstantIntVal>(rowCountIntVal))
         {
             rowCount = (UInt)constRowCount->getValue();
         }
         else
         {
+            auto isLinkTimeVal =
+                as<TypeCastIntVal>(rowCountIntVal) || as<DeclRefIntVal>(rowCountIntVal) ||
+                as<PolynomialIntVal>(rowCountIntVal) || as<FuncCallIntVal>(rowCountIntVal);
+            if (isLinkTimeVal)
+            {
+                auto defaultConstructExpr = m_astBuilder->create<DefaultConstructExpr>();
+                defaultConstructExpr->loc = fromInitializerListExpr->loc;
+                defaultConstructExpr->type = QualType(toType);
+
+                *outToExpr = defaultConstructExpr;
+                return true;
+            }
+
             // We don't know the element count statically,
             // so what are we supposed to be doing?
             //
@@ -1545,7 +1582,6 @@ bool SemanticsVisitor::_coerce(
         return true;
     }
 
-
     // The main general-purpose approach for conversion is
     // using suitable marked initializer ("constructor")
     // declarations on the target type.
diff --git a/source/slang/slang-check-decl.cpp b/source/slang/slang-check-decl.cpp
index c03d8e985..1331839a4 100644
--- a/source/slang/slang-check-decl.cpp
+++ b/source/slang/slang-check-decl.cpp
@@ -2512,6 +2512,23 @@ static Expr* constructDefaultConstructorForType(SemanticsVisitor* visitor, Type*
         return invoke;
     }
 
+    // At the last, we will check if the type is a C-style type, if it is, we will use empty
+    // initializer list to construct the default constructor.
+    HashSet<Type*> visitSet;
+    if (visitor->isCStyleType(type, visitSet))
+    {
+        auto initListExpr = visitor->getASTBuilder()->create<InitializerListExpr>();
+        initListExpr->type = visitor->getASTBuilder()->getInitializerListType();
+        Expr* outExpr = nullptr;
+        auto fromType = type;
+        if (auto atomicType = as<AtomicType>(fromType))
+        {
+            fromType = atomicType->getElementType();
+        }
+        if (visitor->_coerceInitializerList(fromType, &outExpr, initListExpr))
+            return outExpr;
+    }
+
     return nullptr;
 }
 
@@ -13031,7 +13048,13 @@ static Expr* _getParamDefaultValue(SemanticsVisitor* visitor, VarDeclBase* varDe
     if (!isDefaultInitializable(varDecl))
         return nullptr;
 
-    return constructDefaultConstructorForType(visitor, varDecl->type.type);
+    if (auto expr = constructDefaultConstructorForType(visitor, varDecl->type.type))
+    {
+        expr->loc = varDecl->loc;
+        return expr;
+    }
+
+    return nullptr;
 }
 
 bool SemanticsDeclAttributesVisitor::_synthesizeCtorSignature(StructDecl* structDecl)
diff --git a/source/slang/slang-ir-autodiff-transpose.h b/source/slang/slang-ir-autodiff-transpose.h
index 282cc9685..606428efe 100644
--- a/source/slang/slang-ir-autodiff-transpose.h
+++ b/source/slang/slang-ir-autodiff-transpose.h
@@ -1987,6 +1987,9 @@ struct DiffTransposePass
         IRInst* fwdMakeStruct,
         IRInst* revValue)
     {
+        if (fwdMakeStruct->getOperandCount() == 0)
+            return TranspositionResult();
+
         List<RevGradient> gradients;
         auto structType = cast<IRStructType>(fwdMakeStruct->getFullType());
         UInt ii = 0;