mirror of
https://github.com/golang/go
synced 2024-11-19 13:24:42 -07:00
98 lines
1.8 KiB
Go
98 lines
1.8 KiB
Go
// $G $D/$F.go && $L $F.$A && ./$A.out
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// Copyright 2009 The Go Authors. All rights reserved.
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// Use of this source code is governed by a BSD-style
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// license that can be found in the LICENSE file.
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// Interface comparisons using types hidden
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// inside reflected-on structs.
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package main
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import "reflect"
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type T struct {
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f float32
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g float32
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s string
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t string
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u uint32
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v uint32
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w uint32
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x uint32
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y uint32
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z uint32
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}
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func add(s, t string) string {
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return s + t
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}
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func assert(b bool) {
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if !b {
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panic("assert")
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}
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}
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func main() {
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var x T
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x.f = 1.0
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x.g = x.f
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x.s = add("abc", "def")
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x.t = add("abc", "def")
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x.u = 1
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x.v = 2
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x.w = 1 << 28
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x.x = 2 << 28
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x.y = 0x12345678
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x.z = x.y
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// check mem and string
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v := reflect.ValueOf(x)
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i := v.Field(0)
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j := v.Field(1)
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assert(i.Interface() == j.Interface())
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s := v.Field(2)
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t := v.Field(3)
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assert(s.Interface() == t.Interface())
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// make sure different values are different.
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// make sure whole word is being compared,
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// not just a single byte.
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i = v.Field(4)
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j = v.Field(5)
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assert(i.Interface() != j.Interface())
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i = v.Field(6)
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j = v.Field(7)
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assert(i.Interface() != j.Interface())
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i = v.Field(8)
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j = v.Field(9)
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assert(i.Interface() == j.Interface())
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}
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/*
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comparing uncomparable type float32
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throw: interface compare
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panic PC=0x28ceb8 [1]
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throw+0x41 /Users/rsc/goX/src/runtime/runtime.c:54
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throw(0x3014a, 0x0)
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ifaceeq+0x15c /Users/rsc/goX/src/runtime/iface.c:501
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ifaceeq(0x2aa7c0, 0x0, 0x0, 0x0, 0x2aa7c0, ...)
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sys·ifaceeq+0x48 /Users/rsc/goX/src/runtime/iface.c:527
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sys·ifaceeq(0x2aa7c0, 0x0, 0x0, 0x0, 0x2aa7c0, ...)
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main·main+0x190 /Users/rsc/goX/src/cmd/gc/x.go:10
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main·main()
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mainstart+0xf /Users/rsc/goX/src/runtime/amd64/asm.s:53
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mainstart()
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sys·Goexit /Users/rsc/goX/src/runtime/proc.c:124
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sys·Goexit()
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*/
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