test: add tests for escape analysis of function parameters

False positives (var incorrectly escapes) are marked with BAD.

Change-Id: I002ac5965ec6748adafa2c4c657c97d8f7ff75d0
Reviewed-on: https://go-review.googlesource.com/5311Reviewed-by: Keith Randall <khr@golang.org>

test/escape_param.go

+// 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 function parameters.
+
+// In this test almost everything is BAD except the simplest cases
+// where input directly flows to output.
+
+package escape
+
+var sink interface{}
+
+// in -> out
+func param0(p *int) *int { // ERROR "leaking param: p to result ~r1$"
+	return p
+}
+
+func caller0a() {
+	i := 0
+	_ = param0(&i) // ERROR "caller0a &i does not escape$"
+}
+
+func caller0b() {
+	i := 0            // ERROR "moved to heap: i$"
+	sink = param0(&i) // ERROR "&i escapes to heap$" "param0\(&i\) escapes to heap"
+}
+
+// in, in -> out, out
+func param1(p1, p2 *int) (*int, *int) { // ERROR "leaking param: p1 to result ~r2$" "leaking param: p2 to result ~r3$"
+	return p1, p2
+}
+
+func caller1() {
+	i := 0 // ERROR "moved to heap: i$"
+	j := 0
+	sink, _ = param1(&i, &j) // ERROR "&i escapes to heap$" "caller1 &j does not escape$"
+}
+
+// in -> other in
+func param2(p1 *int, p2 **int) { // ERROR "leaking param: p1$" "param2 p2 does not escape$"
+	*p2 = p1
+}
+
+func caller2a() {
+	i := 0 // ERROR "moved to heap: i$"
+	var p *int
+	param2(&i, &p) // ERROR "&i escapes to heap$" "caller2a &p does not escape$"
+	_ = p
+}
+
+func caller2b() {
+	i := 0 // ERROR "moved to heap: i$"
+	var p *int
+	param2(&i, &p) // ERROR "&i escapes to heap$" "caller2b &p does not escape$"
+	sink = p       // ERROR "p escapes to heap$"
+}
+
+// in -> in
+type Pair struct {
+	p1 *int
+	p2 *int
+}
+
+func param3(p *Pair) { // ERROR "leaking param: p$"
+	p.p1 = p.p2
+}
+
+func caller3a() {
+	i := 0            // ERROR "moved to heap: i$"
+	j := 0            // ERROR "moved to heap: j$"
+	p := Pair{&i, &j} // ERROR "&i escapes to heap$" "&j escapes to heap$" "moved to heap: p$"
+	param3(&p)        // ERROR "&p escapes to heap$"
+	_ = p
+}
+
+func caller3b() {
+	i := 0            // ERROR "moved to heap: i$"
+	j := 0            // ERROR "moved to heap: j$"
+	p := Pair{&i, &j} // ERROR "&i escapes to heap$" "&j escapes to heap$" "moved to heap: p$"
+	param3(&p)        // ERROR "&p escapes to heap$"
+	sink = p          // ERROR "p escapes to heap$"
+}
+
+// in -> rcvr
+func (p *Pair) param4(i *int) { // ERROR "\(\*Pair\).param4 p does not escape$" "leaking param: i$"
+	p.p1 = i
+}
+
+func caller4a() {
+	i := 0 // ERROR "moved to heap: i$"
+	p := Pair{}
+	p.param4(&i) // ERROR "&i escapes to heap$" "caller4a p does not escape$"
+	_ = p
+}
+
+func caller4b() {
+	i := 0 // ERROR "moved to heap: i$"
+	p := Pair{}
+	p.param4(&i) // ERROR "&i escapes to heap$" "caller4b p does not escape$"
+	sink = p     // ERROR "p escapes to heap$"
+}
+
+// in -> heap
+func param5(i *int) { // ERROR "leaking param: i$"
+	sink = i // ERROR "i escapes to heap$"
+}
+
+func caller5() {
+	i := 0     // ERROR "moved to heap: i$"
+	param5(&i) // ERROR "&i escapes to heap$"
+}
+
+// *in -> heap
+func param6(i ***int) { // ERROR "leaking param: i$"
+	sink = *i // ERROR "\*i escapes to heap$"
+}
+
+func caller6a() {
+	i := 0      // ERROR "moved to heap: i$"
+	p := &i     // ERROR "&i escapes to heap$" "moved to heap: p$"
+	p2 := &p    // ERROR "&p escapes to heap$" "moved to heap: p2$"
+	param6(&p2) // ERROR "&p2 escapes to heap$"
+}
+
+// **in -> heap
+func param7(i ***int) { // ERROR "leaking param: i$"
+	sink = **i // ERROR "\* \(\*i\) escapes to heap"
+}
+
+func caller7() {
+	i := 0      // ERROR "moved to heap: i$"
+	p := &i     // ERROR "&i escapes to heap$" "moved to heap: p$"
+	p2 := &p    // ERROR "&p escapes to heap$" "moved to heap: p2$"
+	param7(&p2) // ERROR "&p2 escapes to heap$"
+}
+
+// **in -> heap
+func param8(i **int) { // ERROR "param8 i does not escape$"
+	sink = **i // ERROR "\* \(\*i\) escapes to heap"
+}
+
+func caller8() {
+	i := 0
+	p := &i    // ERROR "caller8 &i does not escape$"
+	param8(&p) // ERROR "caller8 &p does not escape$"
+}
+
+// *in -> out
+func param9(p ***int) **int { // ERROR "param9 leaking param p content to result ~r1$"
+	return *p
+}
+
+func caller9a() {
+	i := 0          // ERROR "moved to heap: i$"
+	p := &i         // ERROR "&i escapes to heap$" "moved to heap: p$"
+	p2 := &p        // ERROR "&p escapes to heap$"
+	_ = param9(&p2) // ERROR "caller9a &p2 does not escape$"
+}
+
+func caller9b() {
+	i := 0             // ERROR "moved to heap: i$"
+	p := &i            // ERROR "&i escapes to heap$" "moved to heap: p$"
+	p2 := &p           // ERROR "&p escapes to heap$"
+	sink = param9(&p2) // ERROR "caller9b &p2 does not escape$"  "param9\(&p2\) escapes to heap"
+}
+
+// **in -> out
+func param10(p ***int) *int { // ERROR "param10 leaking param p content to result ~r1$"
+	return **p
+}
+
+func caller10a() {
+	i := 0           // ERROR "moved to heap: i$"
+	p := &i          // ERROR "&i escapes to heap$" "moved to heap: p$"
+	p2 := &p         // ERROR "&p escapes to heap$"
+	_ = param10(&p2) // ERROR "caller10a &p2 does not escape$"
+}
+
+func caller10b() {
+	i := 0              // ERROR "moved to heap: i$"
+	p := &i             // ERROR "&i escapes to heap$" "moved to heap: p$"
+	p2 := &p            // ERROR "&p escapes to heap$"
+	sink = param10(&p2) // ERROR "caller10b &p2 does not escape$" "param10\(&p2\) escapes to heap"
+}
+
+// &in -> out
+func param11(i **int) ***int { // ERROR "moved to heap: i$"
+	return &i // ERROR "&i escapes to heap$"
+}
+
+func caller11a() {
+	i := 0          // ERROR "moved to heap: i$"
+	p := &i         // ERROR "&i escapes to heap$" "moved to heap: p$"
+	_ = param11(&p) // ERROR "&p escapes to heap$"
+}
+
+func caller11b() {
+	i := 0             // ERROR "moved to heap: i$"
+	p := &i            // ERROR "&i escapes to heap$" "moved to heap: p$"
+	sink = param11(&p) // ERROR "&p escapes to heap$" "param11\(&p\) escapes to heap"
+}
+
+func caller11c() {
+	i := 0              // ERROR "moved to heap: i$"
+	p := &i             // ERROR "&i escapes to heap$" "moved to heap: p$"
+	sink = *param11(&p) // ERROR "&p escapes to heap$" "\*param11\(&p\) escapes to heap"
+}
+
+// &in -> rcvr
+type Indir struct {
+	p ***int
+}
+
+func (r *Indir) param12(i **int) { // ERROR "\(\*Indir\).param12 r does not escape$" "moved to heap: i$"
+	r.p = &i // ERROR "&i escapes to heap$"
+}
+
+func caller12a() {
+	i := 0  // ERROR "moved to heap: i$"
+	p := &i // ERROR "&i escapes to heap$" "moved to heap: p$"
+	var r Indir
+	r.param12(&p) // ERROR "&p escapes to heap$" "caller12a r does not escape$"
+	_ = r
+}
+
+func caller12b() {
+	i := 0        // ERROR "moved to heap: i$"
+	p := &i       // ERROR "&i escapes to heap$" "moved to heap: p$"
+	r := &Indir{} // ERROR "caller12b &Indir literal does not escape$"
+	r.param12(&p) // ERROR "&p escapes to heap$"
+	_ = r
+}
+
+func caller12c() {
+	i := 0  // ERROR "moved to heap: i$"
+	p := &i // ERROR "&i escapes to heap$" "moved to heap: p$"
+	r := Indir{}
+	r.param12(&p) // ERROR "&p escapes to heap$" "caller12c r does not escape$"
+	sink = r      // ERROR "r escapes to heap$"
+}
+
+func caller12d() {
+	i := 0  // ERROR "moved to heap: i$"
+	p := &i // ERROR "&i escapes to heap$" "moved to heap: p$"
+	r := Indir{}
+	r.param12(&p) // ERROR "&p escapes to heap$" "caller12d r does not escape$"
+	sink = **r.p  // ERROR "\* \(\*r\.p\) escapes to heap"
+}
+
+// in -> value rcvr
+type Val struct {
+	p **int
+}
+
+func (v Val) param13(i *int) { // ERROR "Val.param13 v does not escape$" "leaking param: i$"
+	*v.p = i
+}
+
+func caller13a() {
+	i := 0 // ERROR "moved to heap: i$"
+	var p *int
+	var v Val
+	v.p = &p      // ERROR "caller13a &p does not escape$"
+	v.param13(&i) // ERROR "&i escapes to heap$"
+	_ = v
+}
+
+func caller13b() {
+	i := 0 // ERROR "moved to heap: i$"
+	var p *int
+	v := Val{&p}  // ERROR "caller13b &p does not escape$"
+	v.param13(&i) // ERROR "&i escapes to heap$"
+	_ = v
+}
+
+func caller13c() {
+	i := 0 // ERROR "moved to heap: i$"
+	var p *int
+	v := &Val{&p} // ERROR "caller13c &Val literal does not escape$" "caller13c &p does not escape$"
+	v.param13(&i) // ERROR "&i escapes to heap$"
+	_ = v
+}
+
+func caller13d() {
+	i := 0     // ERROR "moved to heap: i$"
+	var p *int // ERROR "moved to heap: p$"
+	var v Val
+	v.p = &p      // ERROR "&p escapes to heap$"
+	v.param13(&i) // ERROR "&i escapes to heap$"
+	sink = v      // ERROR "v escapes to heap$"
+}
+
+func caller13e() {
+	i := 0        // ERROR "moved to heap: i$"
+	var p *int    // ERROR "moved to heap: p$"
+	v := Val{&p}  // ERROR "&p escapes to heap$"
+	v.param13(&i) // ERROR "&i escapes to heap$"
+	sink = v      // ERROR "v escapes to heap$"
+}
+
+func caller13f() {
+	i := 0        // ERROR "moved to heap: i$"
+	var p *int    // ERROR "moved to heap: p$"
+	v := &Val{&p} // ERROR "&Val literal escapes to heap$" "&p escapes to heap$"
+	v.param13(&i) // ERROR "&i escapes to heap$"
+	sink = v      // ERROR "v escapes to heap$"
+}
+
+func caller13g() {
+	i := 0 // ERROR "moved to heap: i$"
+	var p *int
+	v := Val{&p}  // ERROR "caller13g &p does not escape$"
+	v.param13(&i) // ERROR "&i escapes to heap$"
+	sink = *v.p   // ERROR "\*v\.p escapes to heap"
+}
+
+func caller13h() {
+	i := 0 // ERROR "moved to heap: i$"
+	var p *int
+	v := &Val{&p} // ERROR "caller13h &Val literal does not escape$" "caller13h &p does not escape$"
+	v.param13(&i) // ERROR "&i escapes to heap$"
+	sink = **v.p  // ERROR "\* \(\*v\.p\) escapes to heap"
+}