github.com/rsc/go@v0.0.0-20150416155037-e040fd465409/test/escape_slice.go (about)

     1  // errorcheck -0 -m -l
     2  
     3  // Copyright 2015 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 escape analysis for slices.
     8  
     9  package escape
    10  
    11  var sink interface{}
    12  
    13  func slice0() {
    14  	var s []*int
    15  	// BAD: i should not escape
    16  	i := 0            // ERROR "moved to heap: i"
    17  	s = append(s, &i) // ERROR "&i escapes to heap"
    18  	_ = s
    19  }
    20  
    21  func slice1() *int {
    22  	var s []*int
    23  	i := 0            // ERROR "moved to heap: i"
    24  	s = append(s, &i) // ERROR "&i escapes to heap"
    25  	return s[0]
    26  }
    27  
    28  func slice2() []*int {
    29  	var s []*int
    30  	i := 0            // ERROR "moved to heap: i"
    31  	s = append(s, &i) // ERROR "&i escapes to heap"
    32  	return s
    33  }
    34  
    35  func slice3() *int {
    36  	var s []*int
    37  	i := 0            // ERROR "moved to heap: i"
    38  	s = append(s, &i) // ERROR "&i escapes to heap"
    39  	for _, p := range s {
    40  		return p
    41  	}
    42  	return nil
    43  }
    44  
    45  func slice4(s []*int) { // ERROR "s does not escape"
    46  	i := 0    // ERROR "moved to heap: i"
    47  	s[0] = &i // ERROR "&i escapes to heap"
    48  }
    49  
    50  func slice5(s []*int) { // ERROR "s does not escape"
    51  	if s != nil {
    52  		s = make([]*int, 10) // ERROR "make\(\[\]\*int, 10\) does not escape"
    53  	}
    54  	i := 0    // ERROR "moved to heap: i"
    55  	s[0] = &i // ERROR "&i escapes to heap"
    56  }
    57  
    58  func slice6() {
    59  	s := make([]*int, 10) // ERROR "make\(\[\]\*int, 10\) does not escape"
    60  	// BAD: i should not escape
    61  	i := 0    // ERROR "moved to heap: i"
    62  	s[0] = &i // ERROR "&i escapes to heap"
    63  	_ = s
    64  }
    65  
    66  func slice7() *int {
    67  	s := make([]*int, 10) // ERROR "make\(\[\]\*int, 10\) does not escape"
    68  	i := 0                // ERROR "moved to heap: i"
    69  	s[0] = &i             // ERROR "&i escapes to heap"
    70  	return s[0]
    71  }
    72  
    73  func slice8() {
    74  	// BAD: i should not escape here
    75  	i := 0          // ERROR "moved to heap: i"
    76  	s := []*int{&i} // ERROR "&i escapes to heap" "literal does not escape"
    77  	_ = s
    78  }
    79  
    80  func slice9() *int {
    81  	i := 0          // ERROR "moved to heap: i"
    82  	s := []*int{&i} // ERROR "&i escapes to heap" "literal does not escape"
    83  	return s[0]
    84  }
    85  
    86  func slice10() []*int {
    87  	i := 0          // ERROR "moved to heap: i"
    88  	s := []*int{&i} // ERROR "&i escapes to heap" "literal escapes to heap"
    89  	return s
    90  }