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https://github.com/golang/go
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e971b6a9be
The next CL will change Unified IR's switch statement handling to convert values to empty interface in some tricky cases. My initial attempt at this accidentally mishandled `case nil:` in some cases, and this wasn't caught by any existing tests. So this CL adds one. Change-Id: Idcfaf0e869dca91be46d665e65d4623dc52bb60f Reviewed-on: https://go-review.googlesource.com/c/go/+/418099 Reviewed-by: Cuong Manh Le <cuong.manhle.vn@gmail.com> Reviewed-by: Keith Randall <khr@google.com> TryBot-Result: Gopher Robot <gobot@golang.org> Reviewed-by: Keith Randall <khr@golang.org> Run-TryBot: Matthew Dempsky <mdempsky@google.com>
418 lines
6.5 KiB
Go
418 lines
6.5 KiB
Go
// run
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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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// Test switch statements.
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package main
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import "os"
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func assert(cond bool, msg string) {
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if !cond {
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print("assertion fail: ", msg, "\n")
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panic(1)
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}
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}
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func main() {
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i5 := 5
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i7 := 7
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hello := "hello"
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switch true {
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case i5 < 5:
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assert(false, "<")
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case i5 == 5:
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assert(true, "!")
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case i5 > 5:
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assert(false, ">")
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}
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switch {
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case i5 < 5:
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assert(false, "<")
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case i5 == 5:
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assert(true, "!")
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case i5 > 5:
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assert(false, ">")
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}
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switch x := 5; true {
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case i5 < x:
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assert(false, "<")
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case i5 == x:
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assert(true, "!")
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case i5 > x:
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assert(false, ">")
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}
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switch x := 5; true {
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case i5 < x:
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assert(false, "<")
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case i5 == x:
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assert(true, "!")
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case i5 > x:
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assert(false, ">")
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}
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switch i5 {
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case 0:
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assert(false, "0")
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case 1:
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assert(false, "1")
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case 2:
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assert(false, "2")
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case 3:
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assert(false, "3")
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case 4:
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assert(false, "4")
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case 5:
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assert(true, "5")
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case 6:
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assert(false, "6")
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case 7:
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assert(false, "7")
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case 8:
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assert(false, "8")
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case 9:
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assert(false, "9")
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default:
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assert(false, "default")
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}
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switch i5 {
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case 0, 1, 2, 3, 4:
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assert(false, "4")
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case 5:
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assert(true, "5")
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case 6, 7, 8, 9:
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assert(false, "9")
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default:
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assert(false, "default")
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}
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switch i5 {
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case 0:
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case 1:
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case 2:
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case 3:
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case 4:
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assert(false, "4")
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case 5:
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assert(true, "5")
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case 6:
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case 7:
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case 8:
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case 9:
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default:
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assert(i5 == 5, "good")
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}
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switch i5 {
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case 0:
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dummy := 0
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_ = dummy
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fallthrough
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case 1:
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dummy := 0
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_ = dummy
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fallthrough
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case 2:
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dummy := 0
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_ = dummy
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fallthrough
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case 3:
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dummy := 0
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_ = dummy
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fallthrough
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case 4:
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dummy := 0
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_ = dummy
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assert(false, "4")
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case 5:
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dummy := 0
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_ = dummy
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fallthrough
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case 6:
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dummy := 0
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_ = dummy
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fallthrough
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case 7:
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dummy := 0
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_ = dummy
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fallthrough
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case 8:
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dummy := 0
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_ = dummy
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fallthrough
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case 9:
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dummy := 0
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_ = dummy
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fallthrough
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default:
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dummy := 0
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_ = dummy
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assert(i5 == 5, "good")
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}
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fired := false
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switch i5 {
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case 0:
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dummy := 0
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_ = dummy
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fallthrough // tests scoping of cases
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case 1:
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dummy := 0
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_ = dummy
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fallthrough
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case 2:
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dummy := 0
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_ = dummy
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fallthrough
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case 3:
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dummy := 0
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_ = dummy
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fallthrough
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case 4:
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dummy := 0
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_ = dummy
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assert(false, "4")
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case 5:
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dummy := 0
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_ = dummy
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fallthrough
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case 6:
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dummy := 0
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_ = dummy
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fallthrough
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case 7:
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dummy := 0
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_ = dummy
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fallthrough
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case 8:
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dummy := 0
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_ = dummy
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fallthrough
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case 9:
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dummy := 0
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_ = dummy
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fallthrough
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default:
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dummy := 0
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_ = dummy
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fired = !fired
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assert(i5 == 5, "good")
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}
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assert(fired, "fired")
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count := 0
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switch i5 {
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case 0:
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count = count + 1
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fallthrough
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case 1:
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count = count + 1
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fallthrough
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case 2:
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count = count + 1
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fallthrough
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case 3:
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count = count + 1
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fallthrough
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case 4:
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count = count + 1
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assert(false, "4")
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case 5:
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count = count + 1
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fallthrough
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case 6:
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count = count + 1
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fallthrough
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case 7:
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count = count + 1
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fallthrough
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case 8:
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count = count + 1
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fallthrough
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case 9:
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count = count + 1
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fallthrough
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default:
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assert(i5 == count, "good")
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}
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assert(fired, "fired")
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switch hello {
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case "wowie":
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assert(false, "wowie")
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case "hello":
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assert(true, "hello")
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case "jumpn":
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assert(false, "jumpn")
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default:
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assert(false, "default")
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}
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fired = false
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switch i := i5 + 2; i {
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case i7:
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fired = true
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default:
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assert(false, "fail")
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}
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assert(fired, "var")
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// switch on nil-only comparison types
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switch f := func() {}; f {
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case nil:
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assert(false, "f should not be nil")
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default:
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}
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switch m := make(map[int]int); m {
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case nil:
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assert(false, "m should not be nil")
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default:
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}
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switch a := make([]int, 1); a {
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case nil:
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assert(false, "m should not be nil")
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default:
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}
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// switch on interface.
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switch i := interface{}("hello"); i {
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case 42:
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assert(false, `i should be "hello"`)
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case "hello":
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assert(true, "hello")
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default:
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assert(false, `i should be "hello"`)
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}
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// switch on implicit bool converted to interface
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// was broken: see issue 3980
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switch i := interface{}(true); {
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case i:
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assert(true, "true")
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case false:
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assert(false, "i should be true")
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default:
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assert(false, "i should be true")
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}
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// switch on interface with constant cases differing by type.
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// was rejected by compiler: see issue 4781
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type T int
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type B bool
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type F float64
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type S string
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switch i := interface{}(float64(1.0)); i {
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case nil:
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assert(false, "i should be float64(1.0)")
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case (*int)(nil):
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assert(false, "i should be float64(1.0)")
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case 1:
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assert(false, "i should be float64(1.0)")
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case T(1):
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assert(false, "i should be float64(1.0)")
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case F(1.0):
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assert(false, "i should be float64(1.0)")
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case 1.0:
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assert(true, "true")
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case "hello":
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assert(false, "i should be float64(1.0)")
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case S("hello"):
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assert(false, "i should be float64(1.0)")
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case true, B(false):
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assert(false, "i should be float64(1.0)")
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case false, B(true):
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assert(false, "i should be float64(1.0)")
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}
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// switch on array.
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switch ar := [3]int{1, 2, 3}; ar {
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case [3]int{1, 2, 3}:
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assert(true, "[1 2 3]")
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case [3]int{4, 5, 6}:
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assert(false, "ar should be [1 2 3]")
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default:
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assert(false, "ar should be [1 2 3]")
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}
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// switch on channel
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switch c1, c2 := make(chan int), make(chan int); c1 {
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case nil:
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assert(false, "c1 did not match itself")
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case c2:
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assert(false, "c1 did not match itself")
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case c1:
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assert(true, "chan")
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default:
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assert(false, "c1 did not match itself")
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}
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// empty switch
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switch {
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}
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// empty switch with default case.
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fired = false
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switch {
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default:
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fired = true
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}
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assert(fired, "fail")
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// Default and fallthrough.
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count = 0
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switch {
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default:
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count++
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fallthrough
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case false:
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count++
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}
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assert(count == 2, "fail")
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// fallthrough to default, which is not at end.
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count = 0
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switch i5 {
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case 5:
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count++
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fallthrough
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default:
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count++
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case 6:
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count++
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}
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assert(count == 2, "fail")
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i := 0
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switch x := 5; {
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case i < x:
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os.Exit(0)
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case i == x:
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case i > x:
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os.Exit(1)
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}
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// Unified IR converts the tag and all case values to empty
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// interface, when any of the case values aren't assignable to the
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// tag value's type. Make sure that `case nil:` compares against the
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// tag type's nil value (i.e., `(*int)(nil)`), not nil interface
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// (i.e., `any(nil)`).
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switch (*int)(nil) {
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case nil:
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// ok
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case any(nil):
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assert(false, "case any(nil) matched")
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default:
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assert(false, "default matched")
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}
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}
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