Underlying constructor for type alias should always be substituted

Otherwise PSI2IR fails because of type mismatch.

core/descriptors/src/org/jetbrains/kotlin/descriptors/impl/FunctionDescriptorImpl.java

@@ -599,6 +599,7 @@ public abstract class FunctionDescriptorImpl extends DeclarationDescriptorNonRoo
         final TypeSubstitutor substitutor = DescriptorSubstitutor.substituteTypeParameters(
                 unsubstitutedTypeParameters, configuration.substitution, substitutedDescriptor, substitutedTypeParameters, wereChanges
         );
+        if (substitutor == null) return null;
 
         KotlinType substitutedReceiverParameterType = null;
         if (configuration.newExtensionReceiverParameterType != null) {
@@ -768,6 +769,15 @@ public abstract class FunctionDescriptorImpl extends DeclarationDescriptorNonRoo
         return visitor.visitFunctionDescriptor(this, data);
     }
 
+    @Nullable
+    public static List<ValueParameterDescriptor> getSubstitutedValueParameters(
+            FunctionDescriptor substitutedDescriptor,
+            @NotNull List<ValueParameterDescriptor> unsubstitutedValueParameters,
+            @NotNull TypeSubstitutor substitutor
+    ) {
+        return getSubstitutedValueParameters(substitutedDescriptor, unsubstitutedValueParameters, substitutor, false, false, null);
+    }
+
     @Nullable
     public static List<ValueParameterDescriptor> getSubstitutedValueParameters(
             FunctionDescriptor substitutedDescriptor,

core/descriptors/src/org/jetbrains/kotlin/descriptors/impl/TypeAliasConstructorDescriptor.kt

@@ -175,27 +175,26 @@ class TypeAliasConstructorDescriptorImpl private constructor(
             constructor: ClassConstructorDescriptor
         ): TypeAliasConstructorDescriptor? {
             val substitutorForUnderlyingClass = typeAliasDescriptor.getTypeSubstitutorForUnderlyingClass() ?: return null
+            val substitutedConstructor = constructor.substitute(substitutorForUnderlyingClass) ?: return null
 
             val typeAliasConstructor =
                 TypeAliasConstructorDescriptorImpl(
-                    storageManager, typeAliasDescriptor, constructor, null, constructor.annotations,
+                    storageManager, typeAliasDescriptor,
+                    substitutedConstructor,
+                    null, constructor.annotations,
                     constructor.kind, typeAliasDescriptor.source
                 )
 
             val valueParameters =
                 FunctionDescriptorImpl.getSubstitutedValueParameters(
-                    typeAliasConstructor, constructor.valueParameters, substitutorForUnderlyingClass, false, false,
-                    null
+                    typeAliasConstructor, constructor.valueParameters, substitutorForUnderlyingClass
                 ) ?: return null
 
-            val returnType = run {
-                val returnTypeNoAbbreviation = substitutorForUnderlyingClass.substitute(constructor.returnType, Variance.INVARIANT)
-                        ?: return null
-                returnTypeNoAbbreviation.unwrap().lowerIfFlexible().withAbbreviation(typeAliasDescriptor.defaultType)
-            }
+            val returnType = substitutedConstructor.returnType.unwrap().lowerIfFlexible().withAbbreviation(typeAliasDescriptor.defaultType)
 
-            val receiverParameterType =
-                constructor.dispatchReceiverParameter?.let { substitutorForUnderlyingClass.safeSubstitute(it.type, Variance.INVARIANT) }
+            val receiverParameterType = constructor.dispatchReceiverParameter?.let {
+                substitutorForUnderlyingClass.safeSubstitute(it.type, Variance.INVARIANT)
+            }
 
             typeAliasConstructor.initialize(
                 receiverParameterType,

core/descriptors/src/org/jetbrains/kotlin/types/DescriptorSubstitutor.java

@@ -40,10 +40,12 @@ public class DescriptorSubstitutor {
             @NotNull DeclarationDescriptor newContainingDeclaration,
             @NotNull @Mutable List<TypeParameterDescriptor> result
     ) {
-        return substituteTypeParameters(typeParameters, originalSubstitution, newContainingDeclaration, result, null);
+        TypeSubstitutor substitutor = substituteTypeParameters(typeParameters, originalSubstitution, newContainingDeclaration, result, null);
+        if (substitutor == null) throw new AssertionError("Substitution failed");
+        return substitutor;
     }
 
-    @NotNull
+    @Nullable
     public static TypeSubstitutor substituteTypeParameters(
             @ReadOnly @NotNull List<TypeParameterDescriptor> typeParameters,
             @NotNull TypeSubstitution originalSubstitution,
@@ -80,7 +82,7 @@ public class DescriptorSubstitutor {
             TypeParameterDescriptorImpl substituted = substitutedMap.get(descriptor);
             for (KotlinType upperBound : descriptor.getUpperBounds()) {
                 KotlinType substitutedBound = substitutor.substitute(upperBound, Variance.IN_VARIANCE);
-                assert substitutedBound != null : "Upper bound failed to substitute: " + descriptor;
+                if (substitutedBound == null) return null;
 
                 if (substitutedBound != upperBound && wereChanges != null) {
                     wereChanges[0] = true;