1 files changed, 32 insertions, 16 deletions

diff --git a/source/slang/syntax.cpp b/source/slang/syntax.cpp
index 0af318c9e..709206278 100644
--- a/source/slang/syntax.cpp
+++ b/source/slang/syntax.cpp
@@ -330,7 +330,7 @@ void Type::accept(IValVisitor* visitor, void* extra)
 
 
 
-    bool ArrayExpressionType::EqualsImpl(Type * type)
+    bool ArrayExpressionType::EqualsImpl(Type* type)
     {
         auto arrType = as<ArrayExpressionType>(type);
         if (!arrType)
@@ -444,8 +444,13 @@ void Type::accept(IValVisitor* visitor, void* extra)
             }
 
         case RequirementWitness::Flavor::val:
-            return RequirementWitness(
-                getVal()->Substitute(subst));
+            {
+                auto val = getVal();
+                SLANG_ASSERT(val);
+
+                return RequirementWitness(
+                    val->Substitute(subst));
+            }
         }
     }
 
@@ -1336,8 +1341,6 @@ void Type::accept(IValVisitor* visitor, void* extra)
 
     RefPtr<Substitutions> GenericSubstitution::applySubstitutionsShallow(SubstitutionSet substSet, RefPtr<Substitutions> substOuter, int* ioDiff)
     {
-        SLANG_ASSERT(this);
-
         int diff = 0;
 
         if(substOuter != outer) diff++;
@@ -1361,8 +1364,11 @@ void Type::accept(IValVisitor* visitor, void* extra)
     bool GenericSubstitution::Equals(Substitutions* subst)
     {
         // both must be NULL, or non-NULL
-        if (!this || !subst)
-            return !this && !subst;
+        if (subst == nullptr)
+            return false;
+        if (this == subst)
+            return true;
+
         auto genericSubst = as<GenericSubstitution>(subst);
         if (!genericSubst)
             return false;
@@ -1388,8 +1394,6 @@ void Type::accept(IValVisitor* visitor, void* extra)
 
     RefPtr<Substitutions> ThisTypeSubstitution::applySubstitutionsShallow(SubstitutionSet substSet, RefPtr<Substitutions> substOuter, int* ioDiff)
     {
-        SLANG_ASSERT(this);
-
         int diff = 0;
 
         if(substOuter != outer) diff++;
@@ -1409,9 +1413,10 @@ void Type::accept(IValVisitor* visitor, void* extra)
 
     bool ThisTypeSubstitution::Equals(Substitutions* subst)
     {
-        SLANG_ASSERT(this);
         if (!subst)
             return false;
+        if (subst == this)
+            return true;
 
         if (auto thisTypeSubst = as<ThisTypeSubstitution>(subst))
         {
@@ -1462,6 +1467,9 @@ void Type::accept(IValVisitor* visitor, void* extra)
     {
         if (!subst)
             return false;
+        if (subst == this)
+            return true;
+
         if (auto genSubst = as<GlobalGenericParamSubstitution>(subst))
         {
             if (paramDecl != genSubst->paramDecl)
@@ -1485,13 +1493,16 @@ void Type::accept(IValVisitor* visitor, void* extra)
 
     RefPtr<Type> DeclRefBase::Substitute(RefPtr<Type> type) const
     {
+        // Note that type can be nullptr, and so this function can return nullptr (although only correctly when no substitutions) 
+
         // No substitutions? Easy.
         if (!substitutions)
             return type;
 
+        SLANG_ASSERT(type);
+
         // Otherwise we need to recurse on the type structure
         // and apply substitutions where it makes sense
-
         return type->Substitute(substitutions).as<Type>();
     }
 
@@ -1555,6 +1566,7 @@ void Type::accept(IValVisitor* visitor, void* extra)
         RefPtr<Substitutions>   restSubst,
         int*                    ioDiff)
     {
+        SLANG_ASSERT(substToSpecialize);
         return substToSpecialize->applySubstitutionsShallow(substsToApply, restSubst, ioDiff);
     }
 
@@ -1949,7 +1961,6 @@ void Type::accept(IValVisitor* visitor, void* extra)
 
     RefPtr<Val> Val::Substitute(SubstitutionSet subst)
     {
-        SLANG_ASSERT(this);
         if (!subst) return this;
         int diff = 0;
         return SubstituteImpl(subst, &diff);
@@ -2437,11 +2448,16 @@ void Type::accept(IValVisitor* visitor, void* extra)
         return name->text;
     }
 
-    bool SubstitutionSet::Equals(SubstitutionSet substSet) const
+    bool SubstitutionSet::Equals(const SubstitutionSet& substSet) const
     {
-        if(!substitutions || !substSet.substitutions)
-            return substitutions == substSet.substitutions;
-
+        if (substitutions == substSet.substitutions)
+        {
+            return true;
+        }
+        if (substitutions == nullptr || substSet.substitutions == nullptr)
+        {
+            return false;
+        }
         return substitutions->Equals(substSet.substitutions);
     }