diff options
Diffstat (limited to 'src/strings')
| -rw-r--r-- | src/strings/clone.go | 5 | ||||
| -rw-r--r-- | src/strings/clone_test.go | 11 |
2 files changed, 15 insertions, 1 deletions
diff --git a/src/strings/clone.go b/src/strings/clone.go index 6097c6cc88..edd1497d9e 100644 --- a/src/strings/clone.go +++ b/src/strings/clone.go @@ -16,7 +16,12 @@ import ( // overuse of Clone can make programs use more memory. // Clone should typically be used only rarely, and only when // profiling indicates that it is needed. +// For strings of length zero the string "" will be returned +// and no allocation is made. func Clone(s string) string { + if len(s) == 0 { + return "" + } b := make([]byte, len(s)) copy(b, s) return *(*string)(unsafe.Pointer(&b)) diff --git a/src/strings/clone_test.go b/src/strings/clone_test.go index 5396771047..a9ba8add23 100644 --- a/src/strings/clone_test.go +++ b/src/strings/clone_test.go @@ -11,9 +11,13 @@ import ( "unsafe" ) +var emptyString string + func TestClone(t *testing.T) { var cloneTests = []string{ "", + strings.Clone(""), + strings.Repeat("a", 42)[:0], "short", strings.Repeat("a", 42), } @@ -25,9 +29,14 @@ func TestClone(t *testing.T) { inputHeader := (*reflect.StringHeader)(unsafe.Pointer(&input)) cloneHeader := (*reflect.StringHeader)(unsafe.Pointer(&clone)) - if inputHeader.Data == cloneHeader.Data { + if len(input) != 0 && cloneHeader.Data == inputHeader.Data { t.Errorf("Clone(%q) return value should not reference inputs backing memory.", input) } + + emptyHeader := (*reflect.StringHeader)(unsafe.Pointer(&emptyString)) + if len(input) == 0 && cloneHeader.Data != emptyHeader.Data { + t.Errorf("Clone(%#v) return value should be equal to empty string.", inputHeader) + } } } |