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// Copyright 2021 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.
package test
import (
"fmt"
"sort"
"testing"
)
// Test that calling methods on generic types doesn't cause allocations.
func genericSorted[T sort.Interface](data T) bool {
n := data.Len()
for i := n - 1; i > 0; i-- {
if data.Less(i, i-1) {
return false
}
}
return true
}
func TestGenericSorted(t *testing.T) {
var data = sort.IntSlice{-10, -5, 0, 1, 2, 3, 5, 7, 11, 100, 100, 100, 1000, 10000}
f := func() {
genericSorted(data)
}
if n := testing.AllocsPerRun(10, f); n > 0 {
t.Errorf("got %f allocs, want 0", n)
}
}
// Test that escape analysis correctly tracks escaping inside of methods
// called on generic types.
type fooer interface {
foo()
}
type P struct {
p *int
q int
}
var esc []*int
func (p P) foo() {
esc = append(esc, p.p) // foo escapes the pointer from inside of p
}
func f[T fooer](t T) {
t.foo()
}
func TestGenericEscape(t *testing.T) {
for i := 0; i < 4; i++ {
var x int = 77 + i
var p P = P{p: &x}
f(p)
}
for i, p := range esc {
if got, want := *p, 77+i; got != want {
panic(fmt.Sprintf("entry %d: got %d, want %d", i, got, want))
}
}
}