From 071f1b6062b459928ebfd6f2f60a8d6ad021112b Mon Sep 17 00:00:00 2001
From: Yong He <yonghe@outlook.com>
Date: Wed, 14 Aug 2024 18:41:48 -0700
Subject: Variadic Generics Part 1: parsing and type checking. (#4833)

---
 source/slang/slang-check-expr.cpp | 120 +++++++++++++++++++++++++++++++++++++-
 1 file changed, 118 insertions(+), 2 deletions(-)

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

diff --git a/source/slang/slang-check-expr.cpp b/source/slang/slang-check-expr.cpp
index 96e0a95d0..561d17c00 100644
--- a/source/slang/slang-check-expr.cpp
+++ b/source/slang/slang-check-expr.cpp
@@ -61,7 +61,10 @@ namespace Slang
     Expr* SemanticsVisitor::moveTemp(Expr* const& expr, F const& func)
     {
         VarDecl* varDecl = m_astBuilder->create<VarDecl>();
-        varDecl->parentDecl = nullptr; // TODO: need to fill this in somehow!
+        varDecl->parentDecl = nullptr;
+        if (m_outerScope && m_outerScope->containerDecl)
+            m_outerScope->containerDecl->addMember(varDecl);
+        addModifier(varDecl, m_astBuilder->create<LocalTempVarModifier>());
         varDecl->checkState = DeclCheckState::DefinitionChecked;
         varDecl->nameAndLoc.loc = expr->loc;
         varDecl->initExpr = expr;
@@ -2091,7 +2094,7 @@ namespace Slang
                 getSink()->diagnose(subscriptExpr, Diagnostics::multiDimensionalArrayNotSupported);
             }
 
-            auto elementType = CoerceToUsableType(TypeExp(baseExpr, baseTypeType->getType()));
+            auto elementType = CoerceToUsableType(TypeExp(baseExpr, baseTypeType->getType()), nullptr);
             auto arrayType = getArrayType(
                 m_astBuilder,
                 elementType,
@@ -3466,6 +3469,119 @@ namespace Slang
         return expr;
     }
 
+
+    Expr* SemanticsExprVisitor::visitExpandExpr(ExpandExpr* expr)
+    {
+        OrderedHashSet<Type*> capturedTypePackSet;
+        auto subContext = this->withParentExpandExpr(expr, &capturedTypePackSet);
+        expr->baseExpr = dispatchExpr(expr->baseExpr, subContext);
+
+        Type* patternType = nullptr;
+        bool isTypeExpr = false;
+        if (auto typeType = as<TypeType>(expr->baseExpr->type))
+        {
+            patternType = typeType->getType();
+            isTypeExpr = true;
+        }
+        else
+        {
+            patternType = expr->baseExpr->type;
+        }
+        if (as<ErrorType>(patternType))
+        {
+            expr->type = m_astBuilder->getErrorType();
+            return expr;
+        }
+        if (subContext.getCapturedTypePacks()->getCount() == 0)
+        {
+            getSink()->diagnose(expr, Diagnostics::expandTermCapturesNoTypePacks);
+        }
+        List<Type*> capturedTypePacks;
+        for (auto capturedType : capturedTypePackSet)
+        {
+            capturedTypePacks.add(capturedType);
+        }
+        auto expandType = m_astBuilder->getExpandType(patternType, capturedTypePacks.getArrayView());
+        if (isTypeExpr)
+            expr->type = m_astBuilder->getTypeType(expandType);
+        else
+            expr->type = QualType(expandType);
+        return expr;
+    }
+
+    Expr* SemanticsExprVisitor::visitEachExpr(EachExpr* expr)
+    {
+        if (!m_parentExpandExpr)
+        {
+            getSink()->diagnose(expr, Diagnostics::eachExprMustBeInsideExpandExpr);
+            expr->type = m_astBuilder->getErrorType();
+            return expr;
+        }
+
+        expr->baseExpr = CheckTerm(expr->baseExpr);
+        bool isTypeNode = false;
+        Type* baseType = nullptr;
+        if (auto typeType = as<TypeType>(expr->baseExpr->type))
+        {
+            isTypeNode = true;
+            baseType = typeType->getType();
+        }
+        else
+        {
+            baseType = expr->baseExpr->type;
+        }
+        if (as<ErrorType>(baseType))
+        {
+            expr->type = m_astBuilder->getErrorType();
+            return expr;
+        }
+        if (isTypeNode)
+        {
+            auto declRefType = as<DeclRefType>(baseType);
+            if (!declRefType)
+            {
+                goto error;
+            }
+            if (!declRefType->getDeclRef().as<GenericTypePackParamDecl>())
+            {
+                goto error;
+            }
+        }
+        else
+        {
+            if (!isTypePack(baseType) && !as<TupleType>(baseType))
+                goto error;
+        }
+        {
+            SLANG_ASSERT(m_capturedTypePacks);
+            if (auto baseExpandType = as<ExpandType>(baseType))
+            {
+                for (Index i = 0; i < baseExpandType->getCapturedTypePackCount(); i++)
+                {
+                    auto capturedType = baseExpandType->getCapturedTypePack(i);
+                    m_capturedTypePacks->add(capturedType);
+                }
+            }
+            else
+            {
+                m_capturedTypePacks->add(baseType);
+            }
+            auto eachType = m_astBuilder->getEachType(baseType);
+            if (isTypeNode)
+                expr->type = m_astBuilder->getTypeType(eachType);
+            else
+                expr->type = QualType(eachType);
+            return expr;
+        }
+    error:;
+        expr->type = m_astBuilder->getErrorType();
+        if (!as<ErrorType>(baseType))
+        {
+            getSink()->diagnose(expr, Diagnostics::expectTypePackAfterEach);
+        }
+        return expr;
+    }
+
     void SemanticsExprVisitor::maybeCheckKnownBuiltinInvocation(Expr* invokeExpr)
     {
         auto checkedInvokeExpr = as<InvokeExpr>(invokeExpr);
-- 
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