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// errorcheck -0 -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.
// Test escape analysis for arrays and some large things
package foo
var Ssink *string
type U [2]*string
func bar(a, b *string) U { // ERROR "leaking param: a to result ~r0 level=0$" "leaking param: b to result ~r0 level=0$"
return U{a, b}
}
func foo(x U) U { // ERROR "leaking param: x to result ~r0 level=0$"
return U{x[1], x[0]}
}
func bff(a, b *string) U { // ERROR "leaking param: a to result ~r0 level=0$" "leaking param: b to result ~r0 level=0$"
return foo(foo(bar(a, b)))
}
func tbff1() *string {
a := "cat"
b := "dog" // ERROR "moved to heap: b$"
u := bff(&a, &b)
_ = u[0]
return &b
}
// BAD: need fine-grained analysis to track u[0] and u[1] differently.
func tbff2() *string {
a := "cat" // ERROR "moved to heap: a$"
b := "dog" // ERROR "moved to heap: b$"
u := bff(&a, &b)
_ = u[0]
return u[1]
}
func car(x U) *string { // ERROR "leaking param: x to result ~r0 level=0$"
return x[0]
}
// BAD: need fine-grained analysis to track x[0] and x[1] differently.
func fun(x U, y *string) *string { // ERROR "leaking param: x to result ~r0 level=0$" "leaking param: y to result ~r0 level=0$"
x[0] = y
return x[1]
}
func fup(x *U, y *string) *string { // ERROR "leaking param: x to result ~r0 level=1$" "leaking param: y$"
x[0] = y // leaking y to heap is intended
return x[1]
}
func fum(x *U, y **string) *string { // ERROR "leaking param: x to result ~r0 level=1$" "leaking param content: y$"
x[0] = *y
return x[1]
}
func fuo(x *U, y *U) *string { // ERROR "leaking param: x to result ~r0 level=1$" "leaking param content: y$"
x[0] = y[0]
return x[1]
}
// These two tests verify that:
// small array literals are stack allocated;
// pointers stored in small array literals do not escape;
// large array literals are heap allocated;
// pointers stored in large array literals escape.
func hugeLeaks1(x **string, y **string) { // ERROR "leaking param content: x" "y does not escape"
a := [10]*string{*y}
_ = a
// 4 x 4,000,000 exceeds MaxStackVarSize, therefore it must be heap allocated if pointers are 4 bytes or larger.
b := [4000000]*string{*x} // ERROR "moved to heap: b"
_ = b
}
func hugeLeaks2(x *string, y *string) { // ERROR "leaking param: x" "y does not escape"
a := [10]*string{y}
_ = a
// 4 x 4,000,000 exceeds MaxStackVarSize, therefore it must be heap allocated if pointers are 4 bytes or larger.
b := [4000000]*string{x} // ERROR "moved to heap: b"
_ = b
}
// BAD: x need not leak.
func doesNew1(x *string, y *string) { // ERROR "leaking param: x" "leaking param: y"
a := new([10]*string) // ERROR "new\(\[10\]\*string\) does not escape"
a[0] = x
b := new([65537]*string) // ERROR "new\(\[65537\]\*string\) escapes to heap"
b[0] = y
}
type a10 struct {
s *string
i [10]int32
}
type a65537 struct {
s *string
i [65537]int32
}
// BAD: x need not leak.
func doesNew2(x *string, y *string) { // ERROR "leaking param: x" "leaking param: y"
a := new(a10) // ERROR "new\(a10\) does not escape"
a.s = x
b := new(a65537) // ERROR "new\(a65537\) escapes to heap"
b.s = y
}
// BAD: x need not leak.
func doesMakeSlice(x *string, y *string) { // ERROR "leaking param: x" "leaking param: y"
a := make([]*string, 10) // ERROR "make\(\[\]\*string, 10\) does not escape"
a[0] = x
b := make([]*string, 65537) // ERROR "make\(\[\]\*string, 65537\) escapes to heap"
b[0] = y
}
func nonconstArray() {
n := 32
s1 := make([]int, n) // ERROR "make\(\[\]int, n\) escapes to heap"
s2 := make([]int, 0, n) // ERROR "make\(\[\]int, 0, n\) escapes to heap"
_, _ = s1, s2
}
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