unsafe: clarify when String bytes can be modified

They can be modified when the string returned by String no longer exists.

Fixes #68300

Change-Id: I526a068151f7aad1ab6827504b51a84e7399cafe
Reviewed-on: https://go-review.googlesource.com/c/go/+/596955
Reviewed-by: Keith Randall <khr@google.com>
Reviewed-by: Keith Randall <khr@golang.org>
Reviewed-by: Than McIntosh <thanm@google.com>
Commit-Queue: Ian Lance Taylor <iant@golang.org>
Auto-Submit: Ian Lance Taylor <iant@golang.org>
LUCI-TryBot-Result: Go LUCI <golang-scoped@luci-project-accounts.iam.gserviceaccount.com>

diff --git a/src/unsafe/unsafe.go b/src/unsafe/unsafe.go
index 8d6cacb8b559b97f8fd76b6f9b1450a4b86d63a7..645ddf2c8aa63b884363fb9bbbe48acd06046227 100644 (file)
--- a/src/unsafe/unsafe.go
+++ b/src/unsafe/unsafe.go
@@ -260,7 +260,7 @@ func SliceData(slice []ArbitraryType) *ArbitraryType
 // a run-time panic occurs.
 //
 // Since Go strings are immutable, the bytes passed to String
-// must not be modified afterwards.
+// must not be modified as long as the returned string value exists.
 func String(ptr *byte, len IntegerType) string
 
 // StringData returns a pointer to the underlying bytes of str.