libgo/go/cmd/vet/testdata/copylock_func.go

   1 // Copyright 2013 The Go Authors. All rights reserved.
   2 // Use of this source code is governed by a BSD-style
   3 // license that can be found in the LICENSE file.
   4
   5 // This file contains tests for the copylock checker's
   6 // function declaration analysis.
   7
   8 package testdata
   9
  10 import "sync"
  11
  12 func OkFunc(*sync.Mutex) {}
  13 func BadFunc(sync.Mutex) {} // ERROR "BadFunc passes lock by value: sync.Mutex"
  14 func BadFunc2(sync.Map)  {} // ERROR "BadFunc2 passes lock by value: sync.Map contains sync.Mutex"
  15 func OkRet() *sync.Mutex {}
  16 func BadRet() sync.Mutex {} // Don't warn about results
  17
  18 var (
  19         OkClosure   = func(*sync.Mutex) {}
  20         BadClosure  = func(sync.Mutex) {} // ERROR "func passes lock by value: sync.Mutex"
  21         BadClosure2 = func(sync.Map) {}   // ERROR "func passes lock by value: sync.Map contains sync.Mutex"
  22 )
  23
  24 type EmbeddedRWMutex struct {
  25         sync.RWMutex
  26 }
  27
  28 func (*EmbeddedRWMutex) OkMeth() {}
  29 func (EmbeddedRWMutex) BadMeth() {} // ERROR "BadMeth passes lock by value: testdata.EmbeddedRWMutex"
  30 func OkFunc(e *EmbeddedRWMutex)  {}
  31 func BadFunc(EmbeddedRWMutex)    {} // ERROR "BadFunc passes lock by value: testdata.EmbeddedRWMutex"
  32 func OkRet() *EmbeddedRWMutex    {}
  33 func BadRet() EmbeddedRWMutex    {} // Don't warn about results
  34
  35 type FieldMutex struct {
  36         s sync.Mutex
  37 }
  38
  39 func (*FieldMutex) OkMeth()   {}
  40 func (FieldMutex) BadMeth()   {} // ERROR "BadMeth passes lock by value: testdata.FieldMutex contains sync.Mutex"
  41 func OkFunc(*FieldMutex)      {}
  42 func BadFunc(FieldMutex, int) {} // ERROR "BadFunc passes lock by value: testdata.FieldMutex contains sync.Mutex"
  43
  44 type L0 struct {
  45         L1
  46 }
  47
  48 type L1 struct {
  49         l L2
  50 }
  51
  52 type L2 struct {
  53         sync.Mutex
  54 }
  55
  56 func (*L0) Ok() {}
  57 func (L0) Bad() {} // ERROR "Bad passes lock by value: testdata.L0 contains testdata.L1 contains testdata.L2"
  58
  59 type EmbeddedMutexPointer struct {
  60         s *sync.Mutex // safe to copy this pointer
  61 }
  62
  63 func (*EmbeddedMutexPointer) Ok()      {}
  64 func (EmbeddedMutexPointer) AlsoOk()   {}
  65 func StillOk(EmbeddedMutexPointer)     {}
  66 func LookinGood() EmbeddedMutexPointer {}
  67
  68 type EmbeddedLocker struct {
  69         sync.Locker // safe to copy interface values
  70 }
  71
  72 func (*EmbeddedLocker) Ok()    {}
  73 func (EmbeddedLocker) AlsoOk() {}
  74
  75 type CustomLock struct{}
  76
  77 func (*CustomLock) Lock()   {}
  78 func (*CustomLock) Unlock() {}
  79
  80 func Ok(*CustomLock) {}
  81 func Bad(CustomLock) {} // ERROR "Bad passes lock by value: testdata.CustomLock"
  82
  83 // Passing lock values into interface function arguments
  84 func FuncCallInterfaceArg(f func(a int, b interface{})) {
  85         var m sync.Mutex
  86         var t struct{ lock sync.Mutex }
  87
  88         f(1, "foo")
  89         f(2, &t)
  90         f(3, &sync.Mutex{})
  91         f(4, m) // ERROR "call of f copies lock value: sync.Mutex"
  92         f(5, t) // ERROR "call of f copies lock value: struct.lock sync.Mutex. contains sync.Mutex"
  93         var fntab []func(t)
  94         fntab[0](t) // ERROR "call of fntab.0. copies lock value: struct.lock sync.Mutex. contains sync.Mutex"
  95 }
  96
  97 // Returning lock via interface value
  98 func ReturnViaInterface(x int) (int, interface{}) {
  99         var m sync.Mutex
 100         var t struct{ lock sync.Mutex }
 101
 102         switch x % 4 {
 103         case 0:
 104                 return 0, "qwe"
 105         case 1:
 106                 return 1, &sync.Mutex{}
 107         case 2:
 108                 return 2, m // ERROR "return copies lock value: sync.Mutex"
 109         default:
 110                 return 3, t // ERROR "return copies lock value: struct.lock sync.Mutex. contains sync.Mutex"
 111         }
 112 }
 113
 114 // Some cases that we don't warn about.
 115
 116 func AcceptedCases() {
 117         x := EmbeddedRwMutex{} // composite literal on RHS is OK (#16227)
 118         x = BadRet()           // function call on RHS is OK (#16227)
 119         x = *OKRet()           // indirection of function call on RHS is OK (#16227)
 120 }
 121
 122 // TODO: Unfortunate cases
 123
 124 // Non-ideal error message:
 125 // Since we're looking for Lock methods, sync.Once's underlying
 126 // sync.Mutex gets called out, but without any reference to the sync.Once.
 127 type LocalOnce sync.Once
 128
 129 func (LocalOnce) Bad() {} // ERROR "Bad passes lock by value: testdata.LocalOnce contains sync.Mutex"
 130
 131 // False negative:
 132 // LocalMutex doesn't have a Lock method.
 133 // Nevertheless, it is probably a bad idea to pass it by value.
 134 type LocalMutex sync.Mutex
 135
 136 func (LocalMutex) Bad() {} // WANTED: An error here :(