1 // Copyright 2019 The Go Authors. All rights reserved.
2 // Use of this source code is governed by a BSD-style
3 // license that can be found in the LICENSE file.
4
5 package p
6
7 import "io"
8
9 // Alan's initial report.
10
11 type I interface { f(); String() string }
12 type J interface { g(); String() string }
13
14 type IJ1 = interface { I; J }
15 type IJ2 = interface { f(); g(); String() string }
16
17 var _ = (*IJ1)(nil) == (*IJ2)(nil) // static assert that IJ1 and IJ2 are identical types
18
19 // The canonical example.
20
21 type ReadWriteCloser interface { io.ReadCloser; io.WriteCloser }
22
23 // Some more cases.
24
25 type M interface { m() }
26 type M32 interface { m() int32 }
27 type M64 interface { m() int64 }
28
29 type U1 interface { m() }
30 type U2 interface { m(); M }
31 type U3 interface { M; m() }
32 type U4 interface { M; M; M }
33 type U5 interface { U1; U2; U3; U4 }
34
35 type U6 interface { m(); m /* ERROR duplicate method */ () }
36 type U7 interface { M32 /* ERROR duplicate method */ ; m() }
37 type U8 interface { m(); M32 /* ERROR duplicate method */ }
38 type U9 interface { M32; M64 /* ERROR duplicate method */ }
39
40 // Verify that repeated embedding of the same interface(s)
41 // eliminates duplicate methods early (rather than at the
42 // end) to prevent exponential memory and time use.
43 // Without early elimination, computing T29 may take dozens
44 // of minutes.
45 type (
46 T0 interface { m() }
47 T1 interface { T0; T0 }
48 T2 interface { T1; T1 }
49 T3 interface { T2; T2 }
50 T4 interface { T3; T3 }
51 T5 interface { T4; T4 }
52 T6 interface { T5; T5 }
53 T7 interface { T6; T6 }
54 T8 interface { T7; T7 }
55 T9 interface { T8; T8 }
56
57 T10 interface { T9; T9 }
58 T11 interface { T10; T10 }
59 T12 interface { T11; T11 }
60 T13 interface { T12; T12 }
61 T14 interface { T13; T13 }
62 T15 interface { T14; T14 }
63 T16 interface { T15; T15 }
64 T17 interface { T16; T16 }
65 T18 interface { T17; T17 }
66 T19 interface { T18; T18 }
67
68 T20 interface { T19; T19 }
69 T21 interface { T20; T20 }
70 T22 interface { T21; T21 }
71 T23 interface { T22; T22 }
72 T24 interface { T23; T23 }
73 T25 interface { T24; T24 }
74 T26 interface { T25; T25 }
75 T27 interface { T26; T26 }
76 T28 interface { T27; T27 }
77 T29 interface { T28; T28 }
78 )
79
80 // Verify that m is present.
81 var x T29
82 var _ = x.m
83
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