// x.typ is incomplete.
	if wantType {
		check.errorf(e.Sel, NotAType, "%s is not a type", syntax.Expr(e))
		goto Error
	}

	obj, index, indirect = lookupFieldOrMethod(x.typ, x.mode == variable, check.pkg, sel, false)
	if obj == nil {
		// Don't report another error if the underlying type was invalid (go.dev/issue/49541).
		if !isValid(under(x.typ)) {
			goto Error
		}

}

func TestLookupFieldOrMethodOnNil(t *testing.T) {
	// LookupFieldOrMethod on a nil type is expected to produce a run-time panic.
	defer func() {
		const want = "LookupFieldOrMethod on nil type"
		p := recover()
		if s, ok := p.(string); !ok || s != want {
			t.Fatalf("got %v, want %s", p, want)
		}
	}()
	LookupFieldOrMethod(nil, false, nil, "")
}

func TestLookupFieldOrMethod(t *testing.T) {

			check.use(arg0)
			return
		}

		check.expr(nil, x, selx.X)
		if x.mode == invalid {
			return
		}

		base := derefStructPtr(x.typ)
		sel := selx.Sel.Name
		obj, index, indirect := lookupFieldOrMethod(base, false, check.pkg, sel, false)
		switch obj.(type) {
		case nil:
			check.errorf(x, MissingFieldOrMethod, invalidArg+"%s has no single field %s", base, sel)
			return
		case *Func:

		if xi != nil {
			// All xi methods must exist in y and corresponding signatures must unify.
			xmethods := xi.typeSet().methods
			for _, xm := range xmethods {
				obj, _, _ := LookupFieldOrMethod(y, false, xm.pkg, xm.name)
				if ym, _ := obj.(*Func); ym == nil || !u.nify(xm.typ, ym.typ, exact, p) {
					return false
				}
			}
			return true
		}
	}

			check.use(arg0)
			return
		}

		check.expr(nil, x, selx.X)
		if x.mode == invalid {
			return
		}

		base := derefStructPtr(x.typ)
		sel := selx.Sel.Value
		obj, index, indirect := lookupFieldOrMethod(base, false, check.pkg, sel, false)
		switch obj.(type) {
		case nil:
			check.errorf(x, MissingFieldOrMethod, invalidArg+"%s has no single field %s", base, sel)
			return
		case *Func:

		if xi != nil {
			// All xi methods must exist in y and corresponding signatures must unify.
			xmethods := xi.typeSet().methods
			for _, xm := range xmethods {
				obj, _, _ := LookupFieldOrMethod(y, false, xm.pkg, xm.name)
				if ym, _ := obj.(*Func); ym == nil || !u.nify(xm.typ, ym.typ, exact, p) {
					return false
				}
			}
			return true
		}
	}

pkg go/types, func Id(*Package, string) string
pkg go/types, func Identical(Type, Type) bool
pkg go/types, func Implements(Type, *Interface) bool
pkg go/types, func IsInterface(Type) bool
pkg go/types, func LookupFieldOrMethod(Type, bool, *Package, string) (Object, []int, bool)
pkg go/types, func MissingMethod(Type, *Interface, bool) (*Func, bool)
pkg go/types, func NewArray(Type, int64) *Array
pkg go/types, func NewChan(ChanDir, Type) *Chan

		{"IsInterface", Func, 5},
		{"IsNumeric", Const, 5},
		{"IsOrdered", Const, 5},
		{"IsString", Const, 5},
		{"IsUnsigned", Const, 5},
		{"IsUntyped", Const, 5},
		{"Label", Type, 5},
		{"LookupFieldOrMethod", Func, 5},
		{"Map", Type, 5},
		{"MethodExpr", Const, 5},
		{"MethodSet", Type, 5},
		{"MethodVal", Const, 5},
		{"MissingMethod", Func, 5},
		{"Named", Type, 5},
		{"NewAlias", Func, 22},