5 files changed, 52 insertions, 25 deletions
diff --git a/src/bytes/buffer_test.go b/src/bytes/buffer_test.go
index 322e7367c7..3c964fc6b9 100644
--- a/src/bytes/buffer_test.go
+++ b/src/bytes/buffer_test.go
@@ -7,6 +7,7 @@ package bytes_test
 import (
 	. "bytes"
 	"fmt"
+	"internal/testenv"
 	"io"
 	"math/rand"
 	"strconv"
@@ -100,6 +101,7 @@ var buf Buffer
 // should not result in any allocations.
 // This can be used to reset the underlying []byte of an existing Buffer.
 func TestNewBufferShallow(t *testing.T) {
+	testenv.SkipIfOptimizationOff(t)
 	n := testing.AllocsPerRun(1000, func() {
 		buf = *NewBuffer(testBytes)
 	})
diff --git a/src/bytes/bytes.go b/src/bytes/bytes.go
index 1871814c6e..2a07d2084e 100644
--- a/src/bytes/bytes.go
+++ b/src/bytes/bytes.go
@@ -10,6 +10,7 @@ import (
 	"internal/bytealg"
 	"unicode"
 	"unicode/utf8"
+	_ "unsafe" // for linkname
 )
 
 // Equal reports whether a and b
@@ -568,6 +569,18 @@ func Map(mapping func(r rune) rune, s []byte) []byte {
 	return b
 }
 
+// Despite being an exported symbol,
+// Repeat is linknamed by widely used packages.
+// Notable members of the hall of shame include:
+//   - gitee.com/quant1x/num
+//
+// Do not remove or change the type signature.
+// See go.dev/issue/67401.
+//
+// Note that this comment is not part of the doc comment.
+//
+//go:linkname Repeat
+
 // Repeat returns a new byte slice consisting of count copies of b.
 //
 // It panics if count is negative or if the result of (len(b) * count)
@@ -583,7 +596,7 @@ func Repeat(b []byte, count int) []byte {
 	if count < 0 {
 		panic("bytes: negative Repeat count")
 	}
-	if len(b) >= maxInt/count {
+	if len(b) > maxInt/count {
 		panic("bytes: Repeat output length overflow")
 	}
 	n := len(b) * count
diff --git a/src/bytes/bytes_test.go b/src/bytes/bytes_test.go
index 5e8cf85fd9..200a357bc0 100644
--- a/src/bytes/bytes_test.go
+++ b/src/bytes/bytes_test.go
@@ -1242,33 +1242,48 @@ func repeat(b []byte, count int) (err error) {
 
 // See Issue golang.org/issue/16237
 func TestRepeatCatchesOverflow(t *testing.T) {
-	tests := [...]struct {
+	type testCase struct {
 		s      string
 		count  int
 		errStr string
-	}{
+	}
+
+	runTestCases := func(prefix string, tests []testCase) {
+		for i, tt := range tests {
+			err := repeat([]byte(tt.s), tt.count)
+			if tt.errStr == "" {
+				if err != nil {
+					t.Errorf("#%d panicked %v", i, err)
+				}
+				continue
+			}
+
+			if err == nil || !strings.Contains(err.Error(), tt.errStr) {
+				t.Errorf("%s#%d got %q want %q", prefix, i, err, tt.errStr)
+			}
+		}
+	}
+
+	const maxInt = int(^uint(0) >> 1)
+
+	runTestCases("", []testCase{
 		0: {"--", -2147483647, "negative"},
-		1: {"", int(^uint(0) >> 1), ""},
+		1: {"", maxInt, ""},
 		2: {"-", 10, ""},
 		3: {"gopher", 0, ""},
 		4: {"-", -1, "negative"},
 		5: {"--", -102, "negative"},
 		6: {string(make([]byte, 255)), int((^uint(0))/255 + 1), "overflow"},
-	}
-
-	for i, tt := range tests {
-		err := repeat([]byte(tt.s), tt.count)
-		if tt.errStr == "" {
-			if err != nil {
-				t.Errorf("#%d panicked %v", i, err)
-			}
-			continue
-		}
+	})
 
-		if err == nil || !strings.Contains(err.Error(), tt.errStr) {
-			t.Errorf("#%d expected %q got %q", i, tt.errStr, err)
-		}
+	const is64Bit = 1<<(^uintptr(0)>>63)/2 != 0
+	if !is64Bit {
+		return
 	}
+
+	runTestCases("64-bit", []testCase{
+		0: {"-", maxInt, "out of range"},
+	})
 }
 
 func runesEqual(a, b []rune) bool {
diff --git a/src/bytes/example_test.go b/src/bytes/example_test.go
index 54df5f74e5..1cc0089e41 100644
--- a/src/bytes/example_test.go
+++ b/src/bytes/example_test.go
@@ -10,7 +10,7 @@ import (
 	"fmt"
 	"io"
 	"os"
-	"sort"
+	"slices"
 	"strconv"
 	"unicode"
 )
@@ -165,11 +165,8 @@ func ExampleCompare_search() {
 	// Binary search to find a matching byte slice.
 	var needle []byte
 	var haystack [][]byte // Assume sorted
-	i := sort.Search(len(haystack), func(i int) bool {
-		// Return haystack[i] >= needle.
-		return bytes.Compare(haystack[i], needle) >= 0
-	})
-	if i < len(haystack) && bytes.Equal(haystack[i], needle) {
+	_, found := slices.BinarySearchFunc(haystack, needle, bytes.Compare)
+	if found {
 		// Found it!
 	}
 }
diff --git a/src/bytes/reader.go b/src/bytes/reader.go
index 9ef49014ed..30c46fa6b3 100644
--- a/src/bytes/reader.go
+++ b/src/bytes/reader.go
@@ -152,8 +152,8 @@ func (r *Reader) WriteTo(w io.Writer) (n int64, err error) {
 	return
 }
 
-// Reset resets the [Reader.Reader] to be reading from b.
+// Reset resets the [Reader] to be reading from b.
 func (r *Reader) Reset(b []byte) { *r = Reader{b, 0, -1} }
 
-// NewReader returns a new [Reader.Reader] reading from b.
+// NewReader returns a new [Reader] reading from b.
 func NewReader(b []byte) *Reader { return &Reader{b, 0, -1} }