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      1 // run
      2 
      3 // Copyright 2009 The Go Authors. All rights reserved.
      4 // Use of this source code is governed by a BSD-style
      5 // license that can be found in the LICENSE file.
      6 
      7 // Test various safe uses of indirection.
      8 
      9 package main
     10 
     11 var m0 map[string]int
     12 var m1 *map[string]int
     13 var m2 *map[string]int = &m0
     14 var m3 map[string]int = map[string]int{"a": 1}
     15 var m4 *map[string]int = &m3
     16 
     17 var s0 string
     18 var s1 *string
     19 var s2 *string = &s0
     20 var s3 string = "a"
     21 var s4 *string = &s3
     22 
     23 var a0 [10]int
     24 var a1 *[10]int
     25 var a2 *[10]int = &a0
     26 
     27 var b0 []int
     28 var b1 *[]int
     29 var b2 *[]int = &b0
     30 var b3 []int = []int{1, 2, 3}
     31 var b4 *[]int = &b3
     32 
     33 func crash() {
     34 	// these uses of nil pointers
     35 	// would crash but should type check
     36 	println("crash",
     37 		len(a1)+cap(a1))
     38 }
     39 
     40 func nocrash() {
     41 	// this is spaced funny so that
     42 	// the compiler will print a different
     43 	// line number for each len call if
     44 	// it decides there are type errors.
     45 	// it might also help in the traceback.
     46 	x :=
     47 		len(m0) +
     48 			len(m3)
     49 	if x != 1 {
     50 		println("wrong maplen")
     51 		panic("fail")
     52 	}
     53 
     54 	x =
     55 		len(s0) +
     56 			len(s3)
     57 	if x != 1 {
     58 		println("wrong stringlen")
     59 		panic("fail")
     60 	}
     61 
     62 	x =
     63 		len(a0) +
     64 			len(a2)
     65 	if x != 20 {
     66 		println("wrong arraylen")
     67 		panic("fail")
     68 	}
     69 
     70 	x =
     71 		len(b0) +
     72 			len(b3)
     73 	if x != 3 {
     74 		println("wrong slicelen")
     75 		panic("fail")
     76 	}
     77 
     78 	x =
     79 		cap(b0) +
     80 			cap(b3)
     81 	if x != 3 {
     82 		println("wrong slicecap")
     83 		panic("fail")
     84 	}
     85 }
     86 
     87 func main() { nocrash() }
     88