Initial commit: Go 1.23 release state

test/escape_array.go

@@ -0,0 +1,129 @@
+// 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
+}