<pre>
// invalid array types
type (
	T1 [10]T1                 // element type of T1 is T1
	T2 [10]struct{ f T2 }     // T2 contains T2 as component of a struct
	T3 [10]T4                 // T3 contains T3 as component of a struct in T4
	T4 struct{ f T3 }         // T4 contains T4 as component of array T3 in a struct
)

// valid array types
type (
	T5 [10]*T5                // T5 contains T5 as component of a pointer

	register["S7"] = riscv.REG_S7
	register["S8"] = riscv.REG_S8
	register["S9"] = riscv.REG_S9
	register["S10"] = riscv.REG_S10
	// Skip S11 as it is the g register.
	register["T3"] = riscv.REG_T3
	register["T4"] = riscv.REG_T4
	register["T5"] = riscv.REG_T5
	register["T6"] = riscv.REG_T6

	// Go runtime register names.
	register["g"] = riscv.REG_G
	register["CTXT"] = riscv.REG_CTXT
	register["TMP"] = riscv.REG_TMP

    assertThat(actualSubtype.getActualTypeArguments()[0]).isInstanceOf(WildcardType.class);
  }

  public <T> void testGetSubtype_manyGenericArgs() {
    class FourTypeArgs<T1, T2, T3, T4> {}
    class ThreeTypeArgs<T1, T2, T3> extends FourTypeArgs<T1, T2, T3, String> {}
    TypeToken<FourTypeArgs<T, Integer, ?, ?>> supertype =
        new TypeToken<FourTypeArgs<T, Integer, ?, ?>>() {};

    assertThat(actualSubtype.getActualTypeArguments()[0]).isInstanceOf(WildcardType.class);
  }

  public <T> void testGetSubtype_manyGenericArgs() {
    class FourTypeArgs<T1, T2, T3, T4> {}
    class ThreeTypeArgs<T1, T2, T3> extends FourTypeArgs<T1, T2, T3, String> {}
    TypeToken<FourTypeArgs<T, Integer, ?, ?>> supertype =
        new TypeToken<FourTypeArgs<T, Integer, ?, ?>>() {};

	{"", []string{}},
	{" ", []string{}},
	{" \t ", []string{}},
	{"  abc  ", []string{"abc"}},
	{"1 2 3 4", []string{"1", "2", "3", "4"}},
	{"1  2  3  4", []string{"1", "2", "3", "4"}},
	{"1\t\t2\t\t3\t4", []string{"1", "2", "3", "4"}},
	{"1\u20002\u20013\u20024", []string{"1", "2", "3", "4"}},
	{"\u2000\u2001\u2002", []string{}},
	{"\n™\t™\n", []string{"™", "™"}},
	{faces, []string{faces}},
}

</p>

<pre>
// A struct with four embedded fields of types T1, *T2, P.T3 and *P.T4
struct {
	T1        // field name is T1
	*T2       // field name is T2
	P.T3      // field name is T3
	*P.T4     // field name is T4
	x, y int  // field names are x and y
}
</pre>

<p>
The following declaration is illegal because field names must be unique