sort: use math/rand/v2 in tests and benchmarks

This allows to drop the use of deprecated rand.Seed in benchmarks.

Fixes #61142

Change-Id: I628848c0d4a500dc9a361930c393e47c3361a95c
Reviewed-on: https://go-review.googlesource.com/c/go/+/551155
Reviewed-by: Eli Bendersky <eliben@google.com>
Auto-Submit: Ian Lance Taylor <iant@google.com>
Reviewed-by: Ian Lance Taylor <iant@google.com>
Run-TryBot: Tobias Klauser <tobias.klauser@gmail.com>
Auto-Submit: Tobias Klauser <tobias.klauser@gmail.com>
TryBot-Result: Gopher Robot <gobot@golang.org>
Reviewed-by: Robert Griesemer <gri@google.com>
LUCI-TryBot-Result: Go LUCI <golang-scoped@luci-project-accounts.iam.gserviceaccount.com>

2 files changed, 15 insertions, 15 deletions

diff --git a/src/sort/sort_slices_benchmark_test.go b/src/sort/sort_slices_benchmark_test.go
index 37f3b1bc7e..069536df03 100644
--- a/src/sort/sort_slices_benchmark_test.go
+++ b/src/sort/sort_slices_benchmark_test.go
@@ -5,7 +5,7 @@
 package sort_test
 
 import (
-	"math/rand"
+	"math/rand/v2"
 	"slices"
 	. "sort"
 	"strconv"
@@ -18,10 +18,10 @@ import (
 // package).
 
 func makeRandomInts(n int) []int {
-	rand.Seed(42)
+	r := rand.New(rand.NewPCG(42, 0))
 	ints := make([]int, n)
 	for i := 0; i < n; i++ {
-		ints[i] = rand.Intn(n)
+		ints[i] = r.IntN(n)
 	}
 	return ints
 }
@@ -92,14 +92,14 @@ func BenchmarkSlicesIsSorted(b *testing.B) {
 // makeRandomStrings generates n random strings with alphabetic runes of
 // varying lengths.
 func makeRandomStrings(n int) []string {
-	rand.Seed(42)
+	r := rand.New(rand.NewPCG(42, 0))
 	var letters = []rune("abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ")
 	ss := make([]string, n)
 	for i := 0; i < n; i++ {
 		var sb stringspkg.Builder
-		slen := 2 + rand.Intn(50)
+		slen := 2 + r.IntN(50)
 		for j := 0; j < slen; j++ {
-			sb.WriteRune(letters[rand.Intn(len(letters))])
+			sb.WriteRune(letters[r.IntN(len(letters))])
 		}
 		ss[i] = sb.String()
 	}
@@ -156,10 +156,10 @@ func (s myStructs) Less(i, j int) bool { return s[i].n < s[j].n }
 func (s myStructs) Swap(i, j int)      { s[i], s[j] = s[j], s[i] }
 
 func makeRandomStructs(n int) myStructs {
-	rand.Seed(42)
+	r := rand.New(rand.NewPCG(42, 0))
 	structs := make([]*myStruct, n)
 	for i := 0; i < n; i++ {
-		structs[i] = &myStruct{n: rand.Intn(n)}
+		structs[i] = &myStruct{n: r.IntN(n)}
 	}
 	return structs
 }
diff --git a/src/sort/sort_test.go b/src/sort/sort_test.go
index ccb89873af..ba757a845a 100644
--- a/src/sort/sort_test.go
+++ b/src/sort/sort_test.go
@@ -9,7 +9,7 @@ import (
 	"fmt"
 	"internal/testenv"
 	"math"
-	"math/rand"
+	"math/rand/v2"
 	"slices"
 	. "sort"
 	"strconv"
@@ -110,7 +110,7 @@ func TestSortLarge_Random(t *testing.T) {
 	}
 	data := make([]int, n)
 	for i := 0; i < len(data); i++ {
-		data[i] = rand.Intn(100)
+		data[i] = rand.IntN(100)
 	}
 	if IntsAreSorted(data) {
 		t.Fatalf("terrible rand.rand")
@@ -198,7 +198,7 @@ func TestNonDeterministicComparison(t *testing.T) {
 	}()
 
 	td := &nonDeterministicTestingData{
-		r: rand.New(rand.NewSource(0)),
+		r: rand.New(rand.NewPCG(0, 0)),
 	}
 
 	for i := 0; i < 10; i++ {
@@ -442,13 +442,13 @@ func testBentleyMcIlroy(t *testing.T, sort func(Interface), maxswap func(int) in
 					case _Sawtooth:
 						data[i] = i % m
 					case _Rand:
-						data[i] = rand.Intn(m)
+						data[i] = rand.IntN(m)
 					case _Stagger:
 						data[i] = (i*m + i) % n
 					case _Plateau:
 						data[i] = min(i, m)
 					case _Shuffle:
-						if rand.Intn(m) != 0 {
+						if rand.IntN(m) != 0 {
 							j += 2
 							data[i] = j
 						} else {
@@ -648,7 +648,7 @@ func TestStability(t *testing.T) {
 
 	// random distribution
 	for i := 0; i < len(data); i++ {
-		data[i].a = rand.Intn(m)
+		data[i].a = rand.IntN(m)
 	}
 	if IsSorted(data) {
 		t.Fatalf("terrible rand.rand")
@@ -704,7 +704,7 @@ func countOps(t *testing.T, algo func(Interface), name string) {
 			maxswap: 1<<31 - 1,
 		}
 		for i := 0; i < n; i++ {
-			td.data[i] = rand.Intn(n / 5)
+			td.data[i] = rand.IntN(n / 5)
 		}
 		algo(&td)
 		t.Logf("%s %8d elements: %11d Swap, %10d Less", name, n, td.nswap, td.ncmp)