| 1 | // Tests of bound method closures. |
|---|---|
| 2 | |
| 3 | package main |
| 4 | |
| 5 | import ( |
| 6 | "errors" |
| 7 | "fmt" |
| 8 | ) |
| 9 | |
| 10 | func assert(b bool) { |
| 11 | if !b { |
| 12 | panic("oops") |
| 13 | } |
| 14 | } |
| 15 | |
| 16 | type I int |
| 17 | |
| 18 | func (i I) add(x int) int { |
| 19 | return int(i) + x |
| 20 | } |
| 21 | |
| 22 | func valueReceiver() { |
| 23 | var three I = 3 |
| 24 | assert(three.add(5) == 8) |
| 25 | var add3 func(int) int = three.add |
| 26 | assert(add3(5) == 8) |
| 27 | } |
| 28 | |
| 29 | type S struct{ x int } |
| 30 | |
| 31 | func (s *S) incr() { |
| 32 | s.x++ |
| 33 | } |
| 34 | |
| 35 | func (s *S) get() int { |
| 36 | return s.x |
| 37 | } |
| 38 | |
| 39 | func pointerReceiver() { |
| 40 | ps := new(S) |
| 41 | incr := ps.incr |
| 42 | get := ps.get |
| 43 | assert(get() == 0) |
| 44 | incr() |
| 45 | incr() |
| 46 | incr() |
| 47 | assert(get() == 3) |
| 48 | } |
| 49 | |
| 50 | func addressibleValuePointerReceiver() { |
| 51 | var s S |
| 52 | incr := s.incr |
| 53 | get := s.get |
| 54 | assert(get() == 0) |
| 55 | incr() |
| 56 | incr() |
| 57 | incr() |
| 58 | assert(get() == 3) |
| 59 | } |
| 60 | |
| 61 | type S2 struct { |
| 62 | S |
| 63 | } |
| 64 | |
| 65 | func promotedReceiver() { |
| 66 | var s2 S2 |
| 67 | incr := s2.incr |
| 68 | get := s2.get |
| 69 | assert(get() == 0) |
| 70 | incr() |
| 71 | incr() |
| 72 | incr() |
| 73 | assert(get() == 3) |
| 74 | } |
| 75 | |
| 76 | func anonStruct() { |
| 77 | var s struct{ S } |
| 78 | incr := s.incr |
| 79 | get := s.get |
| 80 | assert(get() == 0) |
| 81 | incr() |
| 82 | incr() |
| 83 | incr() |
| 84 | assert(get() == 3) |
| 85 | } |
| 86 | |
| 87 | func typeCheck() { |
| 88 | var i interface{} |
| 89 | i = (*S).incr |
| 90 | _ = i.(func(*S)) // type assertion: receiver type prepended to params |
| 91 | |
| 92 | var s S |
| 93 | i = s.incr |
| 94 | _ = i.(func()) // type assertion: receiver type disappears |
| 95 | } |
| 96 | |
| 97 | type errString string |
| 98 | |
| 99 | func (err errString) Error() string { |
| 100 | return string(err) |
| 101 | } |
| 102 | |
| 103 | // Regression test for a builder crash. |
| 104 | func regress1(x error) func() string { |
| 105 | return x.Error |
| 106 | } |
| 107 | |
| 108 | // Regression test for b/7269: |
| 109 | // taking the value of an interface method performs a nil check. |
| 110 | func nilInterfaceMethodValue() { |
| 111 | err := errors.New("ok") |
| 112 | f := err.Error |
| 113 | if got := f(); got != "ok" { |
| 114 | panic(got) |
| 115 | } |
| 116 | |
| 117 | err = nil |
| 118 | if got := f(); got != "ok" { |
| 119 | panic(got) |
| 120 | } |
| 121 | |
| 122 | defer func() { |
| 123 | r := fmt.Sprint(recover()) |
| 124 | // runtime panic string varies across toolchains |
| 125 | if r != "interface conversion: interface is nil, not error" && |
| 126 | r != "runtime error: invalid memory address or nil pointer dereference" && |
| 127 | r != "method value: interface is nil" { |
| 128 | panic("want runtime panic from nil interface method value, got " + r) |
| 129 | } |
| 130 | }() |
| 131 | f = err.Error // runtime panic: err is nil |
| 132 | panic("unreachable") |
| 133 | } |
| 134 | |
| 135 | func main() { |
| 136 | valueReceiver() |
| 137 | pointerReceiver() |
| 138 | addressibleValuePointerReceiver() |
| 139 | promotedReceiver() |
| 140 | anonStruct() |
| 141 | typeCheck() |
| 142 | |
| 143 | if e := regress1(errString("hi"))(); e != "hi" { |
| 144 | panic(e) |
| 145 | } |
| 146 | |
| 147 | nilInterfaceMethodValue() |
| 148 | } |
| 149 |
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