For example, preprocessing the following with -C puts y on the wrong line. /* a boring comment */ y Although a problem with -C, the issue is more generic, for example if the raw string literals patch is accepted it would have the same bug.
*** Bug 4388 has been marked as a duplicate of this bug. ***
Fixed here: http://lists.cs.uiuc.edu/pipermail/cfe-commits/Week-of-Mon-20090608/018166.html