internal/span: handle invalid column values to avoid crashing

This might not be necessary after we fix handling for line directives,
but it's always better to avoid the panic here.

Updates golang/go#34433

Change-Id: Ica4fb571dff6753fb15bf8d397c55f713284aa27
Reviewed-on: https://go-review.googlesource.com/c/tools/+/196662
Run-TryBot: Rebecca Stambler <rstambler@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Ian Cottrell <iancottrell@google.com>
This commit is contained in:
Rebecca Stambler 2019-09-20 14:05:10 -04:00
parent 59c6680fe2
commit c85f9fa958

View File

@ -29,6 +29,8 @@ func ToUTF16Column(p Point, content []byte) (int, error) {
if colZero == 0 {
// 0-based column 0, so it must be chr 1
return 1, nil
} else if colZero < 0 {
return -1, fmt.Errorf("ToUTF16Column: column is invalid (%v)", colZero)
}
// work out the offset at the start of the line using the column
lineOffset := offset - colZero
@ -41,6 +43,7 @@ func ToUTF16Column(p Point, content []byte) (int, error) {
// Now, truncate down to the supplied column.
start = start[:colZero]
// and count the number of utf16 characters
// in theory we could do this by hand more efficiently...
return len(utf16.Encode([]rune(string(start)))) + 1, nil