slices: update doc for Delete and Replace

[gostls13.git] / src / slices / slices.go

diff --git a/src/slices/slices.go b/src/slices/slices.go
index 465af14f8e5eeeec2535c2d2d3a64fb1ee61d23e..4c398557ff4241565f5ac776d28561cc53913abb 100644 (file)
--- a/src/slices/slices.go
+++ b/src/slices/slices.go
@@ -130,11 +130,14 @@ func ContainsFunc[S ~[]E, E any](s S, f func(E) bool) bool {
 // Insert panics if i is out of range.
 // This function is O(len(s) + len(v)).
 func Insert[S ~[]E, E any](s S, i int, v ...E) S {
+       n := len(s)
        m := len(v)
        if m == 0 {
+               // Panic if i is not in the range [0:n] inclusive.
+               // See issue 63913.
+               _ = s[:n:n][i:]
                return s
        }
-       n := len(s)
        if i == n {
                return append(s, v...)
        }
@@ -209,7 +212,7 @@ func Insert[S ~[]E, E any](s S, i int, v ...E) S {
 }
 
 // Delete removes the elements s[i:j] from s, returning the modified slice.
-// Delete panics if s[i:j] is not a valid slice of s.
+// Delete panics if j > len(s) or s[i:j] is not a valid slice of s.
 // Delete is O(len(s)-j), so if many items must be deleted, it is better to
 // make a single call deleting them all together than to delete one at a time.
 // Delete might not modify the elements s[len(s)-(j-i):len(s)]. If those
@@ -243,9 +246,10 @@ func DeleteFunc[S ~[]E, E any](s S, del func(E) bool) S {
 }
 
 // Replace replaces the elements s[i:j] by the given v, and returns the
-// modified slice. Replace panics if s[i:j] is not a valid slice of s.
+// modified slice.
+// Replace panics if j > len(s) or s[i:j] is not a valid slice of s.
 func Replace[S ~[]E, E any](s S, i, j int, v ...E) S {
-       _ = s[i:j] // verify that i:j is a valid subslice
+       _ = s[i:j] // bounds check
 
        if i == j {
                return Insert(s, i, v...)