// errorcheck -0 -m -l
-// Copyright 2015 The Go Authors. All rights reserved.
+// 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 function parameters.
-
-// In this test almost everything is BAD except the simplest cases
-// where input directly flows to output.
+// Test escape analysis for arrays and some large things
package foo
type U [2]*string
-func bar(a, b *string) U { // ERROR "leaking param: a to result ~r2 level=0$" "leaking param: b to result ~r2 level=0$"
+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 ~r1 level=0$"
+func foo(x U) U { // ERROR "leaking param: x to result ~r0 level=0$"
return U{x[1], x[0]}
}
-func bff(a, b *string) U { // ERROR "leaking param: a to result ~r2 level=0$" "leaking param: b to result ~r2 level=0$"
+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$"
- u := bff(&a, &b) // ERROR "tbff1 &a does not escape$" "tbff1 &b does not escape$"
+ b := "dog" // ERROR "moved to heap: b$"
+ u := bff(&a, &b)
_ = u[0]
- return &b // ERROR "&b escapes to heap$"
+ return &b
}
// BAD: need fine-grained analysis to track u[0] and u[1] differently.
func tbff2() *string {
- a := "cat" // ERROR "moved to heap: a$"
- b := "dog" // ERROR "moved to heap: b$"
- u := bff(&a, &b) // ERROR "&a escapes to heap$" "&b escapes to heap$"
+ a := "cat" // ERROR "moved to heap: a$"
+ b := "dog" // ERROR "moved to heap: b$"
+ u := bff(&a, &b)
_ = u[0]
return u[1]
}
-func car(x U) *string { // ERROR "leaking param: x to result ~r1 level=0$"
+func car(x U) *string { // ERROR "leaking param: x to result ~r0 level=0$"
return x[0]
}
// BAD: need fine-grained analysis to track x[0] and x[1] differently.
-func fun(x U, y *string) *string { // ERROR "leaking param: x to result ~r2 level=0$" "leaking param: y to result ~r2 level=0$"
+func fun(x U, y *string) *string { // ERROR "leaking param: x to result ~r0 level=0$" "leaking param: y to result ~r0 level=0$"
x[0] = y
return x[1]
}
-func fup(x *U, y *string) *string { // ERROR "leaking param: x to result ~r2 level=1$" "leaking param: y$"
+func fup(x *U, y *string) *string { // ERROR "leaking param: x to result ~r0 level=1$" "leaking param: y$"
x[0] = y // leaking y to heap is intended
return x[1]
}
-// BAD: would be nice to record that *y (content) is what leaks, not y itself
-func fum(x *U, y **string) *string { // ERROR "leaking param: x to result ~r2 level=1$" "leaking param content: y$"
+func fum(x *U, y **string) *string { // ERROR "leaking param: x to result ~r0 level=1$" "leaking param content: y$"
x[0] = *y
return x[1]
}
-// BAD: would be nice to record that y[0] (content) is what leaks, not y itself
-func fuo(x *U, y *U) *string { // ERROR "leaking param: x to result ~r2 level=1$" "leaking param content: y$"
+func fuo(x *U, y *U) *string { // ERROR "leaking param: x to result ~r0 level=1$" "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
+}