Support nested generics

fixes #362

1 files changed, 39 insertions, 22 deletions

diff --git a/source/slang/syntax.cpp b/source/slang/syntax.cpp
index c63dfc781..cdcb623ff 100644
--- a/source/slang/syntax.cpp
+++ b/source/slang/syntax.cpp
@@ -1194,6 +1194,7 @@ void Type::accept(IValVisitor* visitor, void* extra)
         auto substSubst = new GenericSubstitution();
         substSubst->genericDecl = genericDecl;
         substSubst->args = substArgs;
+        substSubst->outer = outerSubst.As<GenericSubstitution>();
         return substSubst;
     }
 
@@ -1897,27 +1898,9 @@ void Type::accept(IValVisitor* visitor, void* extra)
 
     SubstitutionSet substituteSubstitutions(SubstitutionSet oldSubst, SubstitutionSet subst, int * ioDiff)
     {
-        if (oldSubst)
-            oldSubst = oldSubst.substituteImpl(subst, ioDiff);
-
-        // if oldSubst does not have ThisTypeSubst (which means `this_type` is free variable)
-        // and subst has a ThisTypeSubst (which means `this_type` is bound to a type),
-        // then copy that ThisTypeSubst over (to bind the this_type to the specified type)
-        SubstitutionSet newSubst = oldSubst;
-        insertGlobalGenericSubstitutions(newSubst, subst, ioDiff);
-        /*if (!hasThisTypeSubstitutions(oldSubst))
-        {
-            auto thisTypeSubst = findThisTypeSubst(subst);
-            if (thisTypeSubst)
-            {
-                auto cpyThisTypeSubst = new ThisTypeSubstitution();
-                cpyThisTypeSubst->sourceType = thisTypeSubst->sourceType;
-                insertSubstAtBottom(newSubst, cpyThisTypeSubst);
-                *ioDiff = 1;
-            }
-        }*/
-        return newSubst;
+        return oldSubst.substituteImpl(subst, ioDiff);
     }
+
     bool SubstitutionSet::Equals(SubstitutionSet substSet) const
     {
         if (genericSubstitutions)
@@ -1951,8 +1934,8 @@ void Type::accept(IValVisitor* visitor, void* extra)
             rs.globalGenParamSubstitutions = globalGenParamSubstitutions->SubstituteImpl(subst, ioDiff).As<GlobalGenericParamSubstitution>();
         if (thisTypeSubstitution)
             rs.thisTypeSubstitution = thisTypeSubstitution->SubstituteImpl(subst, ioDiff).As<ThisTypeSubstitution>();
-        else
-            rs.thisTypeSubstitution = subst.thisTypeSubstitution;
+
+        insertGlobalGenericSubstitutions(rs, subst, ioDiff);
         return rs;
     }
     int SubstitutionSet::GetHashCode() const
@@ -1966,5 +1949,39 @@ void Type::accept(IValVisitor* visitor, void* extra)
             rs = combineHash(rs, globalGenParamSubstitutions->GetHashCode());
         return rs;
     }
+
+    RefPtr<Substitutions> cloneSubstitutionNonRecursive(RefPtr<Substitutions> subst)
+    {
+        if (!subst)
+            return nullptr;
+        if (auto genSubst = dynamic_cast<GenericSubstitution*>(subst.Ptr()))
+        {
+            RefPtr<GenericSubstitution> newSubst = new GenericSubstitution();
+            newSubst->genericDecl = genSubst->genericDecl;
+
+            for (auto arg : genSubst->args)
+            {
+                newSubst->args.Add(arg);
+            }
+            return newSubst;
+        }
+        else if (auto thisSubst = dynamic_cast<ThisTypeSubstitution*>(subst.Ptr()))
+        {
+            RefPtr<ThisTypeSubstitution> newSubst = new ThisTypeSubstitution();
+            newSubst->sourceType = thisSubst->sourceType;
+            return newSubst;
+        }
+        else if (auto genTypeSubst = dynamic_cast<GlobalGenericParamSubstitution*>(subst.Ptr()))
+        {
+            RefPtr<GlobalGenericParamSubstitution> newSubst = new GlobalGenericParamSubstitution();
+            newSubst->actualType = genTypeSubst->actualType;
+            newSubst->paramDecl = genTypeSubst->paramDecl;
+            newSubst->witnessTables = genTypeSubst->witnessTables;
+            return newSubst;
+        }
+        else
+            SLANG_UNREACHABLE("unimplemented cloneSubstitution");
+        UNREACHABLE_RETURN(nullptr);
+    }
 }