Call Unalias() in IsNilable() to support gotypesalias=1 (#3304)

* Call `Unalias()` in `IsNilable()` to support `gotypesalias=1` Co-authored-by: Gilad Maymon <[email protected]> * Use `types.Unalias` * add nested alias tests --------- Co-authored-by: Gilad Maymon <[email protected]>
99designs · Sep 27, 2024 · 4cdeaa2 · 4cdeaa2
1 parent 8fcf704
commit 4cdeaa2
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diff --git a/codegen/config/binder.go b/codegen/config/binder.go
@@ -520,6 +520,10 @@ func (b *Binder) CopyModifiersFromAst(t *ast.Type, base types.Type) types.Type {
 }
 
 func IsNilable(t types.Type) bool {
+	// Note that we use types.Unalias rather than code.Unalias here
+	// because we want to always check the underlying type.
+	// code.Unalias only unwraps aliases in Go 1.23
+	t = types.Unalias(t)
 	if namedType, isNamed := t.(*types.Named); isNamed {
 		return IsNilable(namedType.Underlying())
 	}

diff --git a/codegen/config/binder_test.go b/codegen/config/binder_test.go
@@ -1,6 +1,8 @@
 package config
 
 import (
+	"fmt"
+	"go/token"
 	"go/types"
 	"testing"
 
@@ -264,3 +266,40 @@ func TestEnumBinding(t *testing.T) {
 	require.Equal(t, bazTwo, baz.EnumValues[1].Object)
 	require.Equal(t, cf.Schema.Types["Baz"].EnumValues[1], baz.EnumValues[1].Definition)
 }
+
+func createTypeAlias(name string, t types.Type) *types.Alias {
+	var nopos token.Pos
+	return types.NewAlias(types.NewTypeName(nopos, nil, name, nil), t)
+}
+
+func TestIsNilable(t *testing.T) {
+	type aTest struct {
+		input    types.Type
+		expected bool
+	}
+
+	theTests := []aTest{
+		{types.Universe.Lookup("any").Type(), true},
+		{types.Universe.Lookup("rune").Type(), false},
+		{types.Universe.Lookup("byte").Type(), false},
+		{types.Universe.Lookup("error").Type(), true},
+		{types.Typ[types.Int], false},
+		{types.Typ[types.String], false},
+		{types.NewChan(types.SendOnly, types.Typ[types.Int]), true},
+		{types.NewPointer(types.Typ[types.Int]), true},
+		{types.NewPointer(types.Typ[types.String]), true},
+		{types.NewMap(types.Typ[types.Int], types.Typ[types.Int]), true},
+		{types.NewSlice(types.Typ[types.Int]), true},
+		{types.NewInterfaceType(nil, nil), true},
+		{createTypeAlias("interfaceAlias", types.NewInterfaceType(nil, nil)), true},
+		{createTypeAlias("interfaceNestedAlias", createTypeAlias("interfaceAlias", types.NewInterfaceType(nil, nil))), true},
+		{createTypeAlias("intAlias", types.Typ[types.Int]), false},
+		{createTypeAlias("intNestedAlias", createTypeAlias("intAlias", types.Typ[types.Int])), false},
+	}
+
+	for _, at := range theTests {
+		t.Run(fmt.Sprintf("nilable-%s", at.input.String()), func(t *testing.T) {
+			require.Equal(t, at.expected, IsNilable(at.input))
+		})
+	}
+}