brkstr2str_pos: avoid case where length is negative

The string that Qt sees is not the original string, since we add
zero-width nonbreaking spaces around it, plus an override character to
force rendering direction. This means that translating positions
between these two representation can be a bit tricky.

We use a max(foo, 0) here to make sure that our intermediate
computation is postive.

Fixes part of bug #12452.
This commit is contained in:
Jean-Marc Lasgouttes 2022-01-23 19:34:11 +01:00
parent 942538c02d
commit ec3a44fef5

View File

@ -535,7 +535,7 @@ docstring::size_type brkstr2str_pos(QString brkstr, docstring const & str, int p
*/
// The variable `brkStrOffset' is here to account for the extra leading characters.
// The ending character zerow_nbsp has to be ignored if the line is complete.
int const qlen = pos - brkStrOffset - (pos == brkstr.length());
int const qlen = max(pos - brkStrOffset - (pos == brkstr.length()), 0);
#if QT_VERSION < 0x040801 || QT_VERSION >= 0x050100
auto const len = qstring_to_ucs4(brkstr.mid(brkStrOffset, qlen)).length();
// Avoid warning