| 1 | // Copyright 2022 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 main |
| 6 | |
| 7 | func a() (r string) { |
| 8 | s := "initial" |
| 9 | var p *struct{ i int } |
| 10 | defer func() { |
| 11 | recover() |
| 12 | r = s |
| 13 | }() |
| 14 | |
| 15 | s, p.i = "set", 2 // s must be set before p.i panics |
| 16 | return "unreachable" |
| 17 | } |
| 18 | |
| 19 | func b() (r string) { |
| 20 | s := "initial" |
| 21 | fn := func() []int { panic("") } |
| 22 | defer func() { |
| 23 | recover() |
| 24 | r = s |
| 25 | }() |
| 26 | |
| 27 | s, fn()[0] = "set", 2 // fn() panics before any assignment occurs |
| 28 | return "unreachable" |
| 29 | } |
| 30 | |
| 31 | func c() (r string) { |
| 32 | s := "initial" |
| 33 | var p map[int]int |
| 34 | defer func() { |
| 35 | recover() |
| 36 | r = s |
| 37 | }() |
| 38 | |
| 39 | s, p[0] = "set", 2 //s must be set before p[0] index panics" |
| 40 | return "unreachable" |
| 41 | } |
| 42 | |
| 43 | func d() (r string) { |
| 44 | s := "initial" |
| 45 | var p map[int]int |
| 46 | defer func() { |
| 47 | recover() |
| 48 | r = s |
| 49 | }() |
| 50 | fn := func() int { panic("") } |
| 51 | |
| 52 | s, p[0] = "set", fn() // fn() panics before s is set |
| 53 | return "unreachable" |
| 54 | } |
| 55 | |
| 56 | func e() (r string) { |
| 57 | s := "initial" |
| 58 | p := map[int]int{} |
| 59 | defer func() { |
| 60 | recover() |
| 61 | r = s |
| 62 | }() |
| 63 | fn := func() int { panic("") } |
| 64 | |
| 65 | s, p[fn()] = "set", 0 // fn() panics before any assignment occurs |
| 66 | return "unreachable" |
| 67 | } |
| 68 | |
| 69 | func f() (r string) { |
| 70 | s := "initial" |
| 71 | p := []int{} |
| 72 | defer func() { |
| 73 | recover() |
| 74 | r = s |
| 75 | }() |
| 76 | |
| 77 | s, p[1] = "set", 0 // p[1] panics after s is set |
| 78 | return "unreachable" |
| 79 | } |
| 80 | |
| 81 | func g() (r string) { |
| 82 | s := "initial" |
| 83 | p := map[any]any{} |
| 84 | defer func() { |
| 85 | recover() |
| 86 | r = s |
| 87 | }() |
| 88 | var i any = func() {} |
| 89 | s, p[i] = "set", 0 // p[i] panics after s is set |
| 90 | return "unreachable" |
| 91 | } |
| 92 | |
| 93 | func h() (r string) { |
| 94 | fail := false |
| 95 | defer func() { |
| 96 | recover() |
| 97 | if fail { |
| 98 | r = "fail" |
| 99 | } else { |
| 100 | r = "success" |
| 101 | } |
| 102 | }() |
| 103 | |
| 104 | type T struct{ f int } |
| 105 | var p *struct{ *T } |
| 106 | |
| 107 | // The implicit "p.T" operand should be evaluated in phase 1 (and panic), |
| 108 | // before the "fail = true" assignment in phase 2. |
| 109 | fail, p.f = true, 0 |
| 110 | return "unreachable" |
| 111 | } |
| 112 | |
| 113 | func main() { |
| 114 | for _, test := range []struct { |
| 115 | fn func() string |
| 116 | want string |
| 117 | desc string |
| 118 | }{ |
| 119 | {a, "set", "s must be set before p.i panics"}, |
| 120 | {b, "initial", "p() panics before s is set"}, |
| 121 | {c, "set", "s must be set before p[0] index panics"}, |
| 122 | {d, "initial", "fn() panics before s is set"}, |
| 123 | {e, "initial", "fn() panics before s is set"}, |
| 124 | {f, "set", "p[1] panics after s is set"}, |
| 125 | {g, "set", "p[i] panics after s is set"}, |
| 126 | {h, "success", "p.T panics before fail is set"}, |
| 127 | } { |
| 128 | if test.fn() != test.want { |
| 129 | panic(test.desc) |
| 130 | } |
| 131 | } |
| 132 | } |
| 133 |
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