Field functions after embedded structs are not visible

[antonmedv]

@diegommm looks like something to broken with the way nature iterates embedded structs and fields as methods.

type Env struct {
	EmbeddedEnv
	Func func() int
}

type EmbeddedEnv struct{}

In this case Func will be not accessible.

[antonmedv]

I added the falling test. Please, take a look.

expr/test/issues/840/issue_test.go

Lines 10 to 30 in 5f4de20

	func TestEnvFieldMethods(t *testing.T) {
	program, err := expr.Compile(`Func(0)`, expr.Env(&Env{}))
	require.NoError(t, err)
	env := &Env{}
	env.Func = func() int {
	return 42
	}
	out, err := expr.Run(program, Env{})
	require.NoError(t, err)
	require.Equal(t, 42, out)
	}
	type Env struct {
	EmbeddedEnv
	Func func() int
	}
	type EmbeddedEnv struct{}

[diegommm]

Will take a look.

[diegommm]

Created a fix in #843