issue22881.go

     1  // run
     2  
     3  // Copyright 2017 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 to make sure RHS is evaluated before map insert is started.
     8  // The RHS panics in all of these cases.
     9  
    10  package main
    11  
    12  import "fmt"
    13  
    14  func main() {
    15  	for i, f := range []func(map[int]int){
    16  		f0, f1, f2, f3, f4, f5, f6, f7, f8,
    17  	} {
    18  		m := map[int]int{}
    19  		func() { // wrapper to scope the defer.
    20  			defer func() {
    21  				recover()
    22  			}()
    23  			f(m) // Will panic. Shouldn't modify m.
    24  			fmt.Printf("RHS didn't panic, case f%d\n", i)
    25  		}()
    26  		if len(m) != 0 {
    27  			fmt.Printf("map insert happened, case f%d\n", i)
    28  		}
    29  	}
    30  
    31  	// Append slice.
    32  	for i, f := range []func(map[int][]int){
    33  		fa0, fa1, fa2, fa3,
    34  	} {
    35  		m := map[int][]int{}
    36  		func() { // wrapper to scope the defer.
    37  			defer func() {
    38  				recover()
    39  			}()
    40  			f(m) // Will panic. Shouldn't modify m.
    41  			fmt.Printf("RHS didn't panic, case fa%d\n", i)
    42  		}()
    43  		if len(m) != 0 {
    44  			fmt.Printf("map insert happened, case fa%d\n", i)
    45  		}
    46  	}
    47  }
    48  
    49  func f0(m map[int]int) {
    50  	var p *int
    51  	m[0] = *p
    52  }
    53  
    54  func f1(m map[int]int) {
    55  	var p *int
    56  	m[0] += *p
    57  }
    58  
    59  func f2(m map[int]int) {
    60  	var p *int
    61  	sink, m[0] = sink, *p
    62  }
    63  
    64  func f3(m map[int]int) {
    65  	var p *chan int
    66  	m[0], sink = <-(*p)
    67  }
    68  
    69  func f4(m map[int]int) {
    70  	var p *interface{}
    71  	m[0], sink = (*p).(int)
    72  }
    73  
    74  func f5(m map[int]int) {
    75  	var p *map[int]int
    76  	m[0], sink = (*p)[0]
    77  }
    78  
    79  func f6(m map[int]int) {
    80  	var z int
    81  	m[0] /= z
    82  }
    83  
    84  func f7(m map[int]int) {
    85  	var a []int
    86  	m[0] = a[0]
    87  }
    88  
    89  func f8(m map[int]int) {
    90  	var z int
    91  	m[0] %= z
    92  }
    93  
    94  func fa0(m map[int][]int) {
    95  	var p *int
    96  	m[0] = append(m[0], *p)
    97  }
    98  
    99  func fa1(m map[int][]int) {
   100  	var p *int
   101  	sink, m[0] = !sink, append(m[0], *p)
   102  }
   103  
   104  func fa2(m map[int][]int) {
   105  	var p *int
   106  	m[0], _ = append(m[0], 0), *p
   107  }
   108  
   109  func fa3(m map[int][]int) {
   110  	// OSLICE has similar in-place-reassignment
   111  	// optimizations as OAPPEND, but we need to make sure
   112  	// to *not* optimize them, because we can't guarantee
   113  	// the slice indices are within bounds.
   114  	m[0] = m[0][:1]
   115  }
   116  
   117  var sink bool
   118
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