gopls/go/ssa/interp/testdata/ifaceconv.go

1	package main
2
3	// Tests of interface conversions and type assertions.
4
5	type I0 interface {
6	}
7	type I1 interface {
8	f()
9	}
10	type I2 interface {
11	f()
12	g()
13	}
14
15	type C0 struct{}
16	type C1 struct{}
17
18	func (C1) f() {}
19
20	type C2 struct{}
21
22	func (C2) f() {}
23	func (C2) g() {}
24
25	func main() {
26	var i0 I0
27	var i1 I1
28	var i2 I2
29
30	// Nil always causes a type assertion to fail, even to the
31	// same type.
32	if _, ok := i0.(I0); ok {
33	panic("nil i0.(I0) succeeded")
34	}
35	if _, ok := i1.(I1); ok {
36	panic("nil i1.(I1) succeeded")
37	}
38	if _, ok := i2.(I2); ok {
39	panic("nil i2.(I2) succeeded")
40	}
41
42	// Conversions can't fail, even with nil.
43	_ = I0(i0)
44
45	_ = I0(i1)
46	_ = I1(i1)
47
48	_ = I0(i2)
49	_ = I1(i2)
50	_ = I2(i2)
51
52	// Non-nil type assertions pass or fail based on the concrete type.
53	i1 = C1{}
54	if _, ok := i1.(I0); !ok {
55	panic("C1 i1.(I0) failed")
56	}
57	if _, ok := i1.(I1); !ok {
58	panic("C1 i1.(I1) failed")
59	}
60	if _, ok := i1.(I2); ok {
61	panic("C1 i1.(I2) succeeded")
62	}
63
64	i1 = C2{}
65	if _, ok := i1.(I0); !ok {
66	panic("C2 i1.(I0) failed")
67	}
68	if _, ok := i1.(I1); !ok {
69	panic("C2 i1.(I1) failed")
70	}
71	if _, ok := i1.(I2); !ok {
72	panic("C2 i1.(I2) failed")
73	}
74
75	// Conversions can't fail.
76	i1 = C1{}
77	if I0(i1) == nil {
78	panic("C1 I0(i1) was nil")
79	}
80	if I1(i1) == nil {
81	panic("C1 I1(i1) was nil")
82	}
83	}
84

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