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fix(types): preserve nested nullability in any binding #244

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a2fd436
fix(testcases): reject non-nullable null literal types
benbellick May 11, 2026
08f6963
fix(types): preserve nested nullability in any binding
benbellick May 11, 2026
57fbacc
test(types): cover parameterized function nullability matching
benbellick May 11, 2026
fcd5381
fix(extensions): enforce any binding nullability
benbellick May 12, 2026
96241cd
refactor(extensions): split top-level any binding
benbellick May 12, 2026
ad26157
docs(extensions): explain any type binding helpers
benbellick May 12, 2026
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98 changes: 69 additions & 29 deletions extensions/variants.go
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Original file line number Diff line number Diff line change
Expand Up @@ -159,6 +159,12 @@ func EvaluateTypeExpression(urn string, nullHandling NullabilityHandling, return
return outType.WithNullability(types.NullabilityNullable), nil
}

if nullHandling == DeclaredOutputNullability {
if anyReturn, ok := returnTypeExpr.(*types.AnyType); ok && anyReturn.Nullability == types.NullabilityRequired {
return outType.WithNullability(types.NullabilityRequired), nil
}
}

return outType, nil
}

Expand Down Expand Up @@ -190,7 +196,7 @@ func matchArguments(nullability NullabilityHandling, paramTypeList FuncParameter
return types.AreSyncTypeParametersMatching(funcDefArgList, actualTypes), nil
}

if err := ValidateConstrainedAnyTypeConsistency(funcDefArgList, actualTypes, variadicBehavior); err != nil {
if err := validateConstrainedAnyTypeConsistency(nullability, funcDefArgList, actualTypes, variadicBehavior); err != nil {
return false, err
}
return true, nil
Expand Down Expand Up @@ -675,30 +681,49 @@ func getLeafParameterizedParams(abstractTypes interface{}) []string {
panic("invalid non-leaf, non-parameterized type param")
}

// validateAnyTypeBinding validates and records the binding of an AnyType parameter to a concrete type.
// It recursively handles nested types (lists, maps, structs).
func validateAnyTypeBinding(paramType types.FuncDefArgType, argType types.Type, bindings map[string]types.Type) error {
// bindAnyType binds a constrained AnyType name to a concrete argument type.
// When ignoreNullability is true, the binding uses the required version of the argument type.
func bindAnyType(anyType *types.AnyType, argType types.Type, bindings map[string]types.Type, ignoreNullability bool) error {
// Plain "any" is unconstrained - each occurrence can be a different type.
if anyType.Name == "any" {
return nil
}

boundType := argType
if boundType.GetNullability() == types.NullabilityUnspecified {
boundType = boundType.WithNullability(types.NullabilityRequired)
}
if ignoreNullability {
boundType = boundType.WithNullability(types.NullabilityRequired)
}

if existingType, exists := bindings[anyType.Name]; exists {
if !existingType.Equals(boundType) {
return fmt.Errorf("%w: type parameter %s cannot be both %s and %s",
substraitgo.ErrInvalidType, anyType.Name,
existingType.ShortString(), boundType.ShortString())
}
} else {
bindings[anyType.Name] = boundType
}
return nil
}

// validateTopLevelAnyTypeBinding handles top-level argument bindings, where MIRROR and DECLARED_OUTPUT ignore outer argument nullability.
func validateTopLevelAnyTypeBinding(nullHandling NullabilityHandling, paramType types.FuncDefArgType, argType types.Type, bindings map[string]types.Type) error {
if anyType, ok := paramType.(*types.AnyType); ok {
return bindAnyType(anyType, argType, bindings,
nullHandling != DiscreteNullability || anyType.Nullability != types.NullabilityRequired)
}
return validateAnyTypeBinding(nullHandling, paramType, argType, bindings)
}

// validateAnyTypeBinding validates nested AnyType bindings, preserving nullability unless the nested AnyType is declared nullable.
// It recursively handles nested types (lists, maps, structs, and functions).
func validateAnyTypeBinding(nullHandling NullabilityHandling, paramType types.FuncDefArgType, argType types.Type, bindings map[string]types.Type) error {
switch p := paramType.(type) {
case *types.AnyType:
// Plain "any" is unconstrained - each occurrence can be a different type
if p.Name == "any" {
return nil
}
if existingType, exists := bindings[p.Name]; exists {
// Compare base types ignoring nullability. Nullability is enforced separately
// at the individual argument level by MatchWithNullability/MatchWithoutNullability
// (see matchArgumentAtCommon in variants.go). Here we only validate that all uses
// of the same type parameter (e.g., any1) resolve to the same base type.
existingBase := existingType.WithNullability(types.NullabilityRequired)
argBase := argType.WithNullability(types.NullabilityRequired)
if !existingBase.Equals(argBase) {
return fmt.Errorf("%w: type parameter %s cannot be both %s and %s",
substraitgo.ErrInvalidType, p.Name,
existingType.ShortString(), argType.ShortString())
}
} else {
bindings[p.Name] = argType
}
return bindAnyType(p, argType, bindings, p.Nullability != types.NullabilityRequired)
case *types.ParameterizedListType:
if listType, ok := argType.(*types.ListType); ok {
params := listType.GetParameters()
Expand All @@ -707,7 +732,7 @@ func validateAnyTypeBinding(paramType types.FuncDefArgType, argType types.Type,
if !ok {
return fmt.Errorf("%w: invalid list element type", substraitgo.ErrInvalidType)
}
if err := validateAnyTypeBinding(p.Type, elementType, bindings); err != nil {
if err := validateAnyTypeBinding(nullHandling, p.Type, elementType, bindings); err != nil {
return err
}
}
Expand All @@ -724,10 +749,10 @@ func validateAnyTypeBinding(paramType types.FuncDefArgType, argType types.Type,
if !ok {
return fmt.Errorf("%w: invalid map value type", substraitgo.ErrInvalidType)
}
if err := validateAnyTypeBinding(p.Key, keyType, bindings); err != nil {
if err := validateAnyTypeBinding(nullHandling, p.Key, keyType, bindings); err != nil {
return err
}
if err := validateAnyTypeBinding(p.Value, valueType, bindings); err != nil {
if err := validateAnyTypeBinding(nullHandling, p.Value, valueType, bindings); err != nil {
return err
}
}
Expand All @@ -742,20 +767,35 @@ func validateAnyTypeBinding(paramType types.FuncDefArgType, argType types.Type,
if !ok {
return fmt.Errorf("%w: invalid struct field type at position %d", substraitgo.ErrInvalidType, i)
}
if err := validateAnyTypeBinding(fieldType, elementType, bindings); err != nil {
if err := validateAnyTypeBinding(nullHandling, fieldType, elementType, bindings); err != nil {
return err
}
}
}
}
}
case *types.ParameterizedFuncType:
if funcType, ok := argType.(*types.FuncType); ok && len(funcType.ParameterTypes) == len(p.Parameters) {
for i, parameterType := range p.Parameters {
if err := validateAnyTypeBinding(nullHandling, parameterType, funcType.ParameterTypes[i], bindings); err != nil {
return err
}
}
if err := validateAnyTypeBinding(nullHandling, p.Return, funcType.ReturnType, bindings); err != nil {
return err
}
}
}
return nil
}

// ValidateConstrainedAnyTypeConsistency validates that all uses of the same AnyN parameter
// (e.g., any1, any2, etc.) resolve to the same concrete type across all arguments
// (e.g., any1, any2, etc.) resolve to the same concrete type across all arguments.
func ValidateConstrainedAnyTypeConsistency(funcParameters []types.FuncDefArgType, argumentTypes []types.Type, variadicBehavior *VariadicBehavior) error {
return validateConstrainedAnyTypeConsistency(MirrorNullability, funcParameters, argumentTypes, variadicBehavior)
}

func validateConstrainedAnyTypeConsistency(nullHandling NullabilityHandling, funcParameters []types.FuncDefArgType, argumentTypes []types.Type, variadicBehavior *VariadicBehavior) error {
// For variadic functions, expand the parameter list to match actual arguments
expandedFuncParameters := funcParameters
if variadicBehavior != nil && len(argumentTypes) > len(funcParameters) {
Expand All @@ -774,7 +814,7 @@ func ValidateConstrainedAnyTypeConsistency(funcParameters []types.FuncDefArgType

// Validate each argument against its parameter type
for i := 0; i < len(expandedFuncParameters) && i < len(argumentTypes); i++ {
if err := validateAnyTypeBinding(expandedFuncParameters[i], argumentTypes[i], bindings); err != nil {
if err := validateTopLevelAnyTypeBinding(nullHandling, expandedFuncParameters[i], argumentTypes[i], bindings); err != nil {
return err
}
}
Expand Down
125 changes: 125 additions & 0 deletions extensions/variants_test.go
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Original file line number Diff line number Diff line change
Expand Up @@ -442,6 +442,92 @@ func valArg(typ types.FuncDefArgType) extensions.ValueArg {
return extensions.ValueArg{Value: &parser.TypeExpression{ValueType: typ}}
}

func mustParseFuncDefArg(t *testing.T, typeExpression string) types.FuncDefArgType {
t.Helper()

typ, err := parser.ParseType(typeExpression)
require.NoError(t, err)
return typ
}

func mustParseConcreteType(t *testing.T, typeExpression string) types.Type {
t.Helper()

typ, err := mustParseFuncDefArg(t, typeExpression).ReturnType(nil, nil)
require.NoError(t, err)
return typ
}

func TestNullabilityAndAnyTypeBindingDocExamples(t *testing.T) {
tests := []struct {
definition string
nullabilityHandling extensions.NullabilityHandling
argTypes []string
returnType string
matches bool
expectedReturnType string
}{
{"f(any1, any1) -> any1", extensions.MirrorNullability, []string{"i32", "i32"}, "any1", true, "i32"},
{"f(any1, any1) -> any1", extensions.MirrorNullability, []string{"i32?", "i32"}, "any1", true, "i32?"},
{"f(any1, any1) -> any1", extensions.MirrorNullability, []string{"i32", "i32?"}, "any1", true, "i32?"},
{"f(any1, any1) -> any1", extensions.MirrorNullability, []string{"i32?", "i32?"}, "any1", true, "i32?"},
{"h(list<any1>, list<any1>) -> list<any1>", extensions.MirrorNullability, []string{"list<i32>", "list<i32>"}, "list<any1>", true, "list<i32>"},
{"h(list<any1>, list<any1>) -> list<any1>", extensions.MirrorNullability, []string{"list?<i32>", "list<i32>"}, "list<any1>", true, "list?<i32>"},
{"h(list<any1>, list<any1>) -> list<any1>", extensions.MirrorNullability, []string{"list<i32?>", "list<i32?>"}, "list<any1>", true, "list<i32?>"},
{"h(list<any1>, list<any1>) -> list<any1>", extensions.MirrorNullability, []string{"list<i32>", "list<i32?>"}, "list<any1>", false, ""},
{"k(func<any1 -> any1>) -> any1", extensions.MirrorNullability, []string{"func<i32 -> i32>"}, "any1", true, "i32"},
{"k(func<any1 -> any1>) -> any1", extensions.MirrorNullability, []string{"func<i32 -> fp64>"}, "any1", false, ""},
{"j(any1, list<any1?>) -> any1", extensions.MirrorNullability, []string{"i32", "list<i32?>"}, "any1", true, "i32"},
{"j(any1, list<any1?>) -> any1", extensions.MirrorNullability, []string{"i32", "list<i32>"}, "any1", false, ""},
{"j(any1, list<any1?>) -> any1", extensions.MirrorNullability, []string{"i32", "list<fp64?>"}, "any1", false, ""},
{"d(any1, any1) -> any1?", extensions.DeclaredOutputNullability, []string{"i32", "i32"}, "any1?", true, "i32?"},
{"d(any1, any1) -> any1?", extensions.DeclaredOutputNullability, []string{"i32?", "i32"}, "any1?", true, "i32?"},
{"d(any1, any1) -> any1?", extensions.DeclaredOutputNullability, []string{"i32?", "i32?"}, "any1?", true, "i32?"},
{"d(any1, any1) -> any1", extensions.DeclaredOutputNullability, []string{"i32", "i32"}, "any1", true, "i32"},
{"d(any1, any1) -> any1", extensions.DeclaredOutputNullability, []string{"i32?", "i32"}, "any1", true, "i32"},
{"d(any1, any1) -> any1", extensions.DeclaredOutputNullability, []string{"i32?", "i32?"}, "any1", true, "i32"},
{"g(any1, any1) -> any1", extensions.DiscreteNullability, []string{"i32", "i32"}, "any1", true, "i32"},
{"g(any1, any1) -> any1", extensions.DiscreteNullability, []string{"i32?", "i32?"}, "any1", false, ""},
{"g(any1, any1) -> any1", extensions.DiscreteNullability, []string{"i32", "i32?"}, "any1", false, ""},
{"g2(any1, any1?) -> any1?", extensions.DiscreteNullability, []string{"i32", "i32?"}, "any1?", true, "i32?"},
{"g2(any1, any1?) -> any1?", extensions.DiscreteNullability, []string{"i32", "i32"}, "any1?", false, ""},
{"g2(any1, any1?) -> any1?", extensions.DiscreteNullability, []string{"i32?", "i32?"}, "any1?", false, ""},
}

for _, tt := range tests {
t.Run(tt.definition+" with "+strings.Join(tt.argTypes, ", "), func(t *testing.T) {
funcParams := strings.TrimSuffix(strings.TrimPrefix(tt.definition[strings.Index(tt.definition, "("):strings.Index(tt.definition, ")")], "("), ")")
paramExpressions := strings.Split(funcParams, ", ")
parameters := make(extensions.FuncParameterList, len(paramExpressions))
for i, paramExpression := range paramExpressions {
parameters[i] = valArg(mustParseFuncDefArg(t, paramExpression))
}

arguments := make([]types.Type, len(tt.argTypes))
for i, argType := range tt.argTypes {
arguments[i] = mustParseConcreteType(t, argType)
}

actual, err := extensions.EvaluateTypeExpression(
"extension:test:def",
tt.nullabilityHandling,
mustParseFuncDefArg(t, tt.returnType),
parameters,
nil,
arguments,
extensions.NewSet())

if !tt.matches {
require.Error(t, err)
return
}

require.NoError(t, err)
require.True(t, mustParseConcreteType(t, tt.expectedReturnType).Equals(actual))
})
}
}

func TestResolveType(t *testing.T) {
// Test TypeReference setting logic for user-defined types
tests := []struct {
Expand Down Expand Up @@ -827,6 +913,45 @@ func TestValidateConstrainedAnyTypeConsistency(t *testing.T) {
require.Contains(t, err.Error(), "type parameter any1 cannot be both i32 and i64")
})

t.Run("nested function types with matching parameter and return types", func(t *testing.T) {
// func(func<any1 -> any1>) with (func<i32 -> i32>)
params := []types.FuncDefArgType{
&types.ParameterizedFuncType{
Parameters: []types.FuncDefArgType{&types.AnyType{Name: "any1"}},
Return: &types.AnyType{Name: "any1"},
},
}
args := []types.Type{
&types.FuncType{
ParameterTypes: []types.Type{&types.Int32Type{}},
ReturnType: &types.Int32Type{},
},
}

err := extensions.ValidateConstrainedAnyTypeConsistency(params, args, nil)
require.NoError(t, err)
})

t.Run("nested function types with mismatched return type fail", func(t *testing.T) {
// func(func<any1 -> any1>) with (func<i32 -> fp64>)
params := []types.FuncDefArgType{
&types.ParameterizedFuncType{
Parameters: []types.FuncDefArgType{&types.AnyType{Name: "any1"}},
Return: &types.AnyType{Name: "any1"},
},
}
args := []types.Type{
&types.FuncType{
ParameterTypes: []types.Type{&types.Int32Type{}},
ReturnType: &types.Float64Type{},
},
}

err := extensions.ValidateConstrainedAnyTypeConsistency(params, args, nil)
require.Error(t, err)
require.Contains(t, err.Error(), "type parameter any1 cannot be both i32 and fp64")
})

t.Run("single any1 parameter is always valid", func(t *testing.T) {
// func(any1) with (i32) - no constraint checking needed
params := []types.FuncDefArgType{
Expand Down
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