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Source file test/escape_because.go

Documentation: test

  // errorcheck -0 -m -m -l
  
  // Copyright 2015 The Go Authors. All rights reserved.
  // Use of this source code is governed by a BSD-style
  // license that can be found in the LICENSE file.
  
  // Note the doubled -m; this tests the "because" explanations for escapes,
  // and is likely to be annoyingly fragile under compiler change.
  // As long as the explanations look reasonably sane, meaning eyeball verify output of
  //    go build -gcflags '-l -m -m' escape_because.go
  // and investigate changes, feel free to update with
  //    go run run.go -update_errors -- escape_because.go
  
  package main
  
  func main() {
  }
  
  var sink interface{}
  
  type pair struct {
  	x, y *int
  }
  
  type Pairy interface {
  	EqualParts() bool
  }
  
  func (p *pair) EqualParts() bool { // ERROR "\(\*pair\).EqualParts p does not escape$"
  	return p != nil && (p.x == p.y || *p.x == *p.y)
  }
  
  func f1(p *int) { // ERROR "from \[3\]\*int literal \(array literal element\) at escape_because.go:34$" "from a \(assigned\) at escape_because.go:34$" "from a \(interface-converted\) at escape_because.go:35$" "from sink \(assigned to top level variable\) at escape_because.go:35$" "leaking param: p$"
  	a := [3]*int{p, nil, nil}
  	sink = a // ERROR "a escapes to heap$" "from sink \(assigned to top level variable\) at escape_because.go:35$"
  
  }
  
  func f2(q *int) { // ERROR "from &u \(address-of\) at escape_because.go:43$" "from &u \(interface-converted\) at escape_because.go:43$" "from pair literal \(struct literal element\) at escape_because.go:41$" "from s \(assigned\) at escape_because.go:40$" "from sink \(assigned to top level variable\) at escape_because.go:43$" "from t \(assigned\) at escape_because.go:41$" "from u \(assigned\) at escape_because.go:42$" "leaking param: q$"
  	s := q
  	t := pair{s, nil}
  	u := t    // ERROR "moved to heap: u$"
  	sink = &u // ERROR "&u escapes to heap$" "from &u \(interface-converted\) at escape_because.go:43$" "from sink \(assigned to top level variable\) at escape_because.go:43$"
  }
  
  func f3(r *int) interface{} { // ERROR "from \[\]\*int literal \(slice-literal-element\) at escape_because.go:47$" "from c \(assigned\) at escape_because.go:47$" "from c \(interface-converted\) at escape_because.go:48$" "from ~r1 \(return\) at escape_because.go:48$" "leaking param: r to result ~r1 level=-1$"
  	c := []*int{r} // ERROR "\[\]\*int literal escapes to heap$" "from c \(assigned\) at escape_because.go:47$" "from c \(interface-converted\) at escape_because.go:48$" "from ~r1 \(return\) at escape_because.go:48$"
  	return c       // "return" // ERROR "c escapes to heap$" "from ~r1 \(return\) at escape_because.go:48$"
  }
  
  func f4(a *int, s []*int) int { // ERROR "from \*s \(indirection\) at escape_because.go:51$" "from append\(s, a\) \(appended to slice\) at escape_because.go:52$" "from append\(s, a\) \(appendee slice\) at escape_because.go:52$" "leaking param content: s$" "leaking param: a$"
  	s = append(s, a)
  	return *(s[0])
  }
  
  func f5(s1, s2 []*int) int { // ERROR "from \*s1 \(indirection\) at escape_because.go:56$" "from \*s2 \(indirection\) at escape_because.go:56$" "from append\(s1, s2...\) \(appended slice...\) at escape_because.go:57$" "from append\(s1, s2...\) \(appendee slice\) at escape_because.go:57$" "leaking param content: s1$" "leaking param content: s2$"
  	s1 = append(s1, s2...)
  	return *(s1[0])
  }
  
  func f6(x, y *int) bool { // ERROR "f6 x does not escape$" "f6 y does not escape$"
  	p := pair{x, y}
  	var P Pairy = &p // ERROR "f6 &p does not escape$"
  	pp := P.(*pair)
  	return pp.EqualParts()
  }
  
  func f7(x map[int]*int, y int) *int { // ERROR "f7 x does not escape$"
  	z, ok := x[y]
  	if !ok {
  		return nil
  	}
  	return z
  }
  
  func f8(x int, y *int) *int { // ERROR "from ~r2 \(return\) at escape_because.go:78$" "from ~r2 \(returned from recursive function\) at escape_because.go:76$" "leaking param: y$" "moved to heap: x$"
  	if x <= 0 {
  		return y
  	}
  	x--
  	return f8(*y, &x) // ERROR "&x escapes to heap$" "from y \(arg to recursive call\) at escape_because.go:81$" "from ~r2 \(return\) at escape_because.go:78$" "from ~r2 \(returned from recursive function\) at escape_because.go:76$"
  }
  
  func f9(x int, y ...*int) *int { // ERROR "from y\[0\] \(dot of pointer\) at escape_because.go:86$" "from ~r2 \(return\) at escape_because.go:86$" "from ~r2 \(returned from recursive function\) at escape_because.go:84$" "leaking param content: y$" "leaking param: y to result ~r2 level=1$" "moved to heap: x$"
  	if x <= 0 {
  		return y[0]
  	}
  	x--
  	return f9(*y[0], &x) // ERROR "&x escapes to heap$" "f9 ... argument does not escape$" "from ... argument \(... arg to recursive call\) at escape_because.go:89$"
  }
  
  func f10(x map[*int]*int, y, z *int) *int { // ERROR "f10 x does not escape$" "from x\[y\] \(key of map put\) at escape_because.go:93$" "from x\[y\] \(value of map put\) at escape_because.go:93$" "leaking param: y$" "leaking param: z$"
  	x[y] = z
  	return z
  }
  
  func f11(x map[*int]*int, y, z *int) map[*int]*int { // ERROR "f11 x does not escape$" "from map\[\*int\]\*int literal \(map literal key\) at escape_because.go:98$" "from map\[\*int\]\*int literal \(map literal value\) at escape_because.go:98$" "leaking param: y$" "leaking param: z$"
  	return map[*int]*int{y: z} // ERROR "from ~r3 \(return\) at escape_because.go:98$" "map\[\*int\]\*int literal escapes to heap$"
  }
  
  func f12() {
  	b := []byte("test") // ERROR "\(\[\]byte\)\(.test.\) escapes to heap$" "from b \(assigned\) at escape_because.go:102$" "from b \(passed to call\[argument escapes\]\) at escape_because.go:103$"
  	escape(b)
  }
  
  func escape(b []byte) { // ERROR "from panic\(b\) \(panic\) at escape_because.go:107$" "leaking param: b$"
  	panic(b)
  }
  
  func f13() {
  	b := []byte("test") // ERROR "\(\[\]byte\)\(.test.\) escapes to heap$" "from .out0 \(passed-to-and-returned-from-call\) at escape_because.go:112$" "from b \(assigned\) at escape_because.go:111$" "from c \(assigned\) at escape_because.go:112$" "from c \(passed to call\[argument escapes\]\) at escape_because.go:113$"
  	c := transmit(b)
  	escape(c)
  }
  
  //go:noinline
  func transmit(b []byte) []byte { // ERROR "from ~r1 \(return\) at escape_because.go:118$" "leaking param: b to result ~r1 level=0$"
  	return b
  }
  
  // The list below is all of the why-escapes messages seen building the escape analysis tests.
  /*
     for i in escape*go ; do echo compile $i; go build -gcflags '-l -m -m' $i >& `basename $i .go`.log ; done
     grep 'from .* at ' escape*.log | sed -e 's/^.*(\([^()]*\))[^()]*$/\1/' | sort -u
  */
  // sed RE above assumes that (reason) is the last parenthesized phrase in the line,
  // and that none of the reasons contains any parentheses
  
  /*
  ... arg to recursive call
  address-of
  appended slice...
  appended to slice
  appendee slice
  arg to ...
  arg to recursive call
  array literal element
  array-element-equals
  assign-pair
  assign-pair-dot-type
  assign-pair-func-call
  assigned
  assigned to top level variable
  call part
  captured by a closure
  closure-var
  converted
  copied slice
  defer func
  defer func ...
  defer func arg
  dot
  dot of pointer
  dot-equals
  fixed-array-index-of
  go func
  go func ...
  go func arg
  indirection
  interface-converted
  key of map put
  map literal key
  map literal value
  parameter to indirect call
  passed to call[argument content escapes]
  passed to call[argument escapes]
  passed-to-and-returned-from-call
  pointer literal
  range
  range-deref
  receiver in indirect call
  return
  returned from recursive function
  send
  slice
  slice-element-equals
  slice-literal-element
  star-dot-equals
  star-equals
  struct literal element
  switch case
  too large for stack
  value of map put
  */
  
  // Expected, but not yet seen (they may be unreachable):
  
  /*
  append-first-arg
  assign-pair-mapr
  assign-pair-receive
  call receiver
  map index
  panic
  pointer literal [assign]
  slice literal element
  */
  

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